United States
Environmental Prote.
Agency
Office of Air
Land and Water Use
Washington DC 20460
EPA 600/5-79-005
March 1979
oEPA
Rest',r .elopmeni
Resource Use and
Residuals Generation
in Households
-------
Resource Use and Residuals Generation
in Households
by
J. KUhner, D. F. Luecke, M. Shapiro
Meta Systems Inc
Cambridge, Massachusetts 02138
Contract No. 68-01-2622
Modification No. 3
Charles N. Ehler
U.S. Environmental Protection Agency
Office of Research and Development
Washington, D.C. 20460
Land Use and Comprehensive Planning Staff
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
-------
FOREWORD
The Environmental Management Research program in the Office of Air, Land,
and Water Use, Office of Research and Development, U.S. Environmental Protection
Agency, is unique in its emphasis on intermedia effects, on the integration of
institutional and technological environmental management strategies, and on a
complete range of implementation measures, including economic incentives, land
use management, public education and traditional regulatory mechanisms.
This report describes energy and water use and the generation of liquid,
solid and gaseous residuals for nine major household functions and their
associated activities. It examines those factors which influence resource use
and residuals generation, summarizes the range of options available to conserve
resources (and reduce residuals discharge), and estimates the costs and benefits
of conservation measures. Indices of resource use and residuals generation are
developed to aid regional residuals environmental quality management analyses.
Courtney Riordan
Acting Deputy Assistant Administrator
Office of Air, Land, and Water Use
-------
ABSTRACT
This report describes, for households, resource use (energy and water
only), the generation of liquid, solid and gaseous residuals (other energy
residuals are not discussed, e.g., heat, noise, etc.), potential conserva-
tion measures and the direct costs, to the household, associated with these
measures. This study focuses on nine major household functions and associated
activities and their relative importance for resource use and residuals genera-
tion. In considering conservation measures, attention is focused on new struc'
tures and factor prices are assumed fixed.
The household activities are organized by function, and the behavioral,
physical and institutional factors which influence energy and water use and
the residuals generation are identified. With this structure the relevant
literature is critically reviewed to provide a basis for estimating use and
generation rates and for assessing the influence, where possible, of the fac-
tors on these rates. Then, conservation measures and estimates of their per-
formance and cost are presented. Resource use and residuals generation rates
and conservation measures are brought together in the context of the factors
which influence them, by utilizing two baselines or benchmarks developed for
single family residences. These baselines are identified as low and high
resource use and residuals generation households. Conservation measures are
imposed on the baselines, direct costs to the households are calculated and
the relative attractiveness of the measures is determined in terms of the
cost/unit reduction in resource use or residual generation.
-------
CONTENTS
Abstract i
List of Figures v
List of Tables v±
List of Abbreviations and Symbols x
Conversion Table xi
Section 1. Introduction 1
Section 2. Conclusion. . 4
Section 3. Recommendations 8
Section 4. Household Functions and Factors Affecting Resource
Use and Residuals Generation 10
Section 5. Household Functions, Resource Use, and
Residuals Generation 22
• Space Heating and Cooling 22
Heating and Cooling Load Tables 22
Computing Fuel Use and Emissions for
Heating and Cooling 23
• Water Heating. . 26
Energy Requirements, Water Use and Residuals
Generation for Water Heating . 27
• Lighting 30
• Kitchen 30
Energy Use and Gaseous Residuals Generation 32
Water Use and Wastewater and Liquid
Residuals Generation 36
Solid Residuals Generation 37
• Washing and Cleaning 37
Clothes Washing and Drying 40
Floor Cleaning 43
• Bathroom . 43
Water Use. 43
Wastewater Generation. . 48
Energy 4 53
• Living and Entertainment 53
• Outdoors 58
Water Use 58
Solid Residuals 59
Stoimwater Runoff 60
• Maintenance 60
Automobile Maintenance 60
• Summary. ....................... 62
ii
-------
CONTENTS (CONTINUED)
Section 6. Conservation Measures and Their Direct Costs 64
• Introduction 64
Space Heating and Cooling 64
Solar Heating and Cooling 69
Costs of Solar Systems 71
• Water Heating 71
Solar Water Heating 73
Lighting 75
• Kitchen 77
Water, Liquid Residuals (and Some Energy) 77
Energy 77
Solid Residuals 78
• Washing and Cleaning 84
Bathroom 85
Toilets 85
Bathing 87
Lavatory 87
Outdoors 89
Water 89
Solid Residuals. 89
Stormwater Runoff 89
• Maintenance^ 91
• Summary 91
Section 7. Resource and Residuals Baselines and the Impact
of Conservation Measures 92
Introduction ', 92
Baselines. 92
Energy and Gaseous Residuals Baselines 93
Water Use and Liquid Residuals Baselines 93
Solid Residuals Baselines 101
Conservation Measures Applied to the Baselines .... 101
Energy 101
Gaseous Residuals 116
Water Use and Liquid Residuals 116
Solid Residuals 122
References. , 131
Appendices
A. Household Function: Detailed Presentation A-l
Introduction .....*. A-l
Space Heating and Cooling i . . A-l
Heating and Cooling Load Tables. A-5
Computer Fuel Use and Emissions for Heating and
Cooling ., . , , . A-8
Water Heating A-12
Inputs and Residuals Generation A-14
iii
-------
CONTENTS (CONTINUED)
Lighting A-22
Kitchen A-22
Energy Consumption and Residuals Generation A-26
Washing and Cleaning A-38
Clothes Washing and Drying Activity A-41
Floor Cleaning A-46
Bathroom . . A-48
Conventional Practice A-51
Living and Entertainment A-62
Outdoors, A-66
Water Use A-66
Solid Residuals A-67
Maintenance ..... A-67
Automobile Maintenance A-68
References A-69
B. Heating, and. Cooling Load Calculations. B-l
Design Heating and Cooling Loads B-l
Design Heat Loss Calculation B-l
Design Cooling Load Calculation B-3
Annual Heating and Cooling Loads B-4
Thermal Conductivity of Structural Components B-4
C. Heat Transmission Coefficient (U) Requirements—Heat Loss of
Selected Thermal Design Standards C-l
One and Two-Family Structures C-l
Multi-Family Structures C-3
D. Residential Solid Wastes D-l
E. Calculation of Baseline Use and Generation Estimates E-l
Energy and Gaseous Residuals E-l
Water and Liquid Residuals E-6
Solid Residuals E-7
iv
-------
FIGURES
Number Page
1 Household Function, Resource Consumption and
Residuals Generation 11
A.I Space Heating: Energy/Residuals A-3
A.2 Cooling: Energy/Residuals A-4
A.3 Water Heating: Materials, Energy, and Residuals A-13
A.4 Lighting—Energy/Residuals A-23
A. 5 Kitchen—Energy/Residuals A-24
A.6 Kitchen—Materials/Residuals A-25
A. 7 Washing and Cleaning: Energy/Residuals A-39
A.8 Washing and Cleaning: Materials/Residuals A-40
A. 9 Bathroom—Residuals Flow A-49
A. 10 Bathroom—Energy Flow A-50
-------
TABLES
Number Page
1 Household Functions and Related Activities 10
2 Functions to be Considered in Terms of Resource Use
and Residuals Generation 12
3 Factors Affecting Energy Use 14
4 Factors Affecting Water Use 17
5 Factors Affecting Generation of Liquid Residuals 19
6 Factors Affecting Solid Residuals Generation 20
7 Insulation in Structures 24
8 Heat Loss—Btu/sq ft/Degree Day 25
9 Cooling Load for Average Outdoor Temperature of 90°F and 85°F ... 25
10 Water Heating Energy Requirement and Water Use 28
11 Estimated Hot Water Use by Activity . 29
12 Residuals Generations Associated with Water Heating 31
13 Appliances in Kitchen and Their Range of Resource
Use and Residual Generation ....... 33
14 Appliances in Kitchen for Hypothetical Low,
Medium and High Energy Households 35
15 Characteristics of Liquid Residuals from Kitchen 38
16 Ranges of Generation Rates for Each Component
of Residential Solid Residuals 39
17 Washing and Cleaning Function: Clothes Washing and Drying 41
18 Electric Energy Use for Floor Cleaning 44
19 Water Use for Bathroom 45
20 Frequency of Toilet Flushing 47
21 Frequency of Bathing 47
22 Comparison of BOD 5 Data for Toilet Flushing Wastewater 49
23 Comparison of Suspended Solids Data for
Toilet Flushing Wastewater. . 50
24 Comparison of Total Nitrogen and Total Phosphorus
Data for Toilet Flushing Wastewater 51
25 Bacteriological Characteristics of Bathing Wastewater 52
26 Comparison of BODs Data for Bathing Wastewater 52
27 Comparison of Suspended Solids Data for Bathing Wastewater 54
28 Lavatory Wastewater Characterization. . . . 54
29 Potential Contribution of Lavatory Input Materials 55
30 Energy Use for Personal Upkeep 56
31 Energy Consumption of Television. ... 57
32 Typical Pollutant Concentrations in Wastewater from
Self-service Auto Washers Over a 10 Month Period 61
33 Incremental Heat Loss Reduction 66
34 Cooling Load Reductions 67
vi
-------
TABLES CCONTINUED)
Number
35 Costs of Insulation and Storm Windows (in New Housing) ...... 68
36 Reduction Due to Switching Window Exposure and Installing
Shading Devices ..,., 70
37 Some Examples of Cost Estimates for Solar Heating Systems 72
38 Effect of Improved ASHRAE Heater Design Standards 74
39 Light Source Efficiencies 76
40 Monthly Space, Time, and Cost Requirements for a
Household for Recovering Solid Residuals , . . 80
41 Measures Influencing Solid Residuals Generation 81
42 Measures Influencing Solid Residuals Generation 82
43 Measures Influencing Solid Residuals Generation , , . . . 83
44 Water Conservation Devices for Bathroom (Toilet) 86
45 Water Conservation for Bathroom (Shower, Bath, Sink) 88
46 Lawn and Garden Irrigation Devices Which May Conserve Water. ... 90
47 Some Characteristics of Baseline "Single Family House" 93
48 Characteristics of Baselines for Energy Use 94
49 Characteristics of Baselines for Water Use and Waste
Water and Liquid Residuals Generation 95
50 Factors Leading to Low and High Baseline
Solid Residuals Generation 96
51 Energy Baselines 97
52 Gaseous Residuals (Ibs/yr) 98
53 Water Use Baselines (gal/yr) . . '. 99
54 Liquid Residuals Baseline (Ibs/yr) 100
55 Solid Residuals Baselines 102
56 Structural Improvements to Reduce Heat Loss 103
57 Energy Savings ' 105
58 Relative Effectiveness of Conservation Measures. ... 106
59 Cooling Load Reductions 108
60 Summary of Selected Conservation Measures for
Heating and Cooling 110
61 Energy Conservation Modifications for Water Heating
With Cost Estimates Ill
62 Water Heating-Energy Savings and Costs 112
63 Energy Conservation Measures in the Kitchen 114
64 Modified Energy Baselines 115
65 Gaseous Residuals of Modified Low and Hiqh Baselines (Ibs/yr). . . 117
66 Water and Liquid Residuals Reductions in the Kitchen 117
67 Water Conservation Measures in Washing and Cleaning 119
68 Water Conservation Measures in the Bathroom 120
69 Effects of Water Saving Devices on Bathroom Water Use 121
70 Reduction of Solid Residuals Generation (Low Baseline) 124
71 Reduction of Low Baseline Solid Residuals (kg/yr) 125
72 Reduction of Solid Residuals Generation (High Baseline) 127
73 Reduction of High Baseline Solid Residuals (kg/yr) 129
vii
-------
TABLES (CONTINUED)
Number Page
A-l Household Functions and Related Activities A-2
A-2 Insulation in Structures. ., A-6
A-3 Heat Loss—BTU/sq ft/Degree Day A-7
A-4 Cooling Load for Average Outdoor Temperatures (90°F and
85°F) A-7
A-5 Emission Rates for Gas and Oil (Ibs/yr) A-9
A-6 Air Emissions due to Fuel Use for Residential Heating .... A-10
A-7 Water Heating Energy and Water Inputs and Residuals
Generated (unit/cap/day) A-15
A-8 Water Heating Energy and Water Inputs and Residuals
Generated (unit/day) A-17
A-9 Gas Consumption for Water Heating, 1971 A-20
A-10 Estimated Hot Water Use A-21
A-ll Appliances in Kitchen and their Range of Resource Use and
Residuals Generation A-27
A-12 Characteristics of Liquid Residuals from Kitchen A-29
A-13 Ranges of Generation Rates for Each Component of Residential
Solid Residuals A-30
A~14 Appliances in Kitchen for Hypothetical Low, Medium and High
Energy Households A-31
A-15 Typical Values of Energy Consumption of Kitchen Appliances. A-34
A-16 Inputs and Residual Outputs; Washing and Cleaning Function:
Clothes Washing and Drying A-42
A-17 Inputs and Residual Outputs per Use; Washing and Cleaning
Function: Clothes Washing and Drying A-44
A-18 Electric Energy Use for Floor Cleaning A-47
A-19 Water Use for Bathroom A-52
A-20 Frequency of Toilet Flushing A-53
A-21 Frequency of Bathing A-53
A-22 Comparison of BOD Data for Toilet Flushing Wastewater. . . A-56
A~23 Comparison of Suspended Solids Data for Toilet Flushing
Wastewater A-57
A~24 Comparison of Total Nitrogen and Total Phosphorus Data for
Toilet Flushing Wastewater A-58
A~25 Bacteriological Characteristics of Bathing Wastewater . . . A-60
A-26 Comparison of BODj. for Bathing Wastewater A-60
A-27 Comparison of Suspended Solids Data for Bathing Wastewater. A-61
A-28 Lavatory Wastewater Characterization A-61
A-29 Potential Contribution of Lavatory Input Materials A-63
viii
-------
TABLE (CONTINUED)
Number
A-30 Energy Use for Personal Upkeep A-64
A-31 Energy Consumption of Television A-65
A-32 Typical Pollutant Concentrations in Wastewater from Self-
Service Auto Washers Over a 10 Month Period A-68
B-l Dimensions B-2
B-2 Climatic Factors for Selected Cities in the U.S B-5
B-3 Indoor Temperature Correction Factor B-7
D-l Description of Residential Solid Residuals D-2
D-2 Components of Solid Residuals Generated Indoors D-4
D-3 Seasonal Variation of Refuse Composition: Franklin, Ohio . D-6
D~4 Material-Flow Estimates of Residential Solid Residuals
Generation , D-7
D-5 Ranges of Generation Rates for Each Component of
Residential Solid Residuals D-9
E-l General Characteristics of Baseline "Single Family Home". . E-l
E~2 Specific Energy Use Characteristics E-2
E~3 Standby Heat Loss Characteristics E-4
E~4 Specific Characteristics for Water Use and Liquid Residuals
Baseline E-6
E~5 Liquid Residuals E-8
E~6 Factors Influencing the Generation of Solid Residuals . . . E-8
E"7 High Baseline Solid Residuals by Component E-9
ix
-------
LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
Btu
Btuh
BOD5
Btu/sq ft/degree day
cu ft
c.v.
°C
OF
gal
gpcd
gpm
gm
hrs
kg
kwh
Ibs
N
%
P
sq ft
SS
TN
TP
yr
—British thermal units
—British thermal units per hour
—five day biochemical oxygen demand
—British thermal units per square foot
per degree day
—cubic feet
—coefficient of variation
—degrees centigrade
—degrees Fahrenheit
—gallon
—gallons per capita per day
—gallons per minute
—grains
—hours
—kilogram
—kilowatt hours
—pounds
—nitrogen
—percent
—phosphorus
—square feet
—suspended solids
—total nitrogen
—total phosphorus
—year
-------
CONVERSION TABLE
Multiply
To Convert To^ by
inches millimeters 25.40
inches centimeters 2.54
feet meters 0.305
square feet square meters 0.093
acres square meters 4047.
cubic feet cubic meters 0.028
pounds kilograms 0.453
gallons cubic meters 0.0038
gallons liter 3.8
galIons/minute cubic meters/minute 0.0038
xi
-------
SECTION 1
INTRODUCTION
This report describes resource use (energy and water only), the genera-
tion of liquid, solid and gaseous residuals* (other energy residuals are not
discussed, e.g. heat, noise, etc.), potential conservation measures for house-
holds, and the direct costs associated with these measures for households.
Other analyses of household activities have relied primarily on per capita use
and generation values derived from aggregate data. This study focuses on nine
major household functions and associated activities and their relative import-
ance for resource use and residuals generation. In considering conservation
measures we focus attention on new structures and we assume fixed factor
prices.
Many concepts presented here were derived from industry studies by
Resources for the Future (RPF)t and from the residuals-environmental quality
management studies initiated by the U.S. Environmental Protection Agency's
(EPA) environmental management program.* Although the approach is not with-
out its critics**, it provides a useful framework for organizing household
functions and activities and a structure for considering the factors which
influence the use of resources and the generation of residuals. The objec-
tives of the study may be stated as follows:
* "The term 'residual1 is used to replace the more traditional but seman-
tically biased terms 'waste1 and 'pollutant.' A residual is a non-product
material or energy output, the value of which is less than the cost of
collecting, processing, and transporting it for use. The definition is time
dependent, i.e., is a function of the level of technology in the society at a
point in time and of the relative costs of alternative inputs. For example,
manure in the United States is now typically a residual, whereas 30 or so years
ago it was a valuable raw material. Residual is defined herein in an economic
sense and should be distinguished from the use of the term in a more narrow
sense in Section 208(b)(2)(J) of the Federal Water Pollution Control Act
Amendments of 1972 (P.L. 92-500), which refers to 'residual waste,' meaning
sludge from wastewater treatment plants." (1)
^ See for a summary: Reference (2)
f For additional information contact: Charles N. Ehler, Media Quality
Management Division, Office of Air, Land and Water Use, Office of Research
and Development, U.S. E.P.A., V7ashington, D.C. 20460.
See, for example, Reference (3).
-------
1. to determine those factors which influence resource use and residuals
generation and their reduction in the residential setting by collecting and
organizing information in the literature; and to estimate response, quantita-
tively where possible, to changes in the factors;
2. to summarize and analyze information on the range of options avail-
able to households to conserve resources and to reduce residuals discharge;
3. to determine the direct costs to households for reducing resource
use and residuals discharge; and
4. to develop indices of resource use and residuals generation for
household activities which may aid regional residuals environmental quality
management analyses.
There are three major components under which the factors influencing use
and generation rates, and their reduction and the costs of reduction, can be
organized.
1. the behavioral component;
2. the physical/technological component; and
3. the administrative/institutional component.
From the point of the household, the first component reflects endogenous fac-
tors (e.g., thermostat setting or frequency of bathing) which are solely
defined by the household. Under the second component factors such as level
of insulation and type of plumbing fixtures are, to some extent, under the
control of the household. They are partly endogenous and partly exogenous.
In the case of the third component the factors are almost totally exogenous
to the individual household (e.g. building codes or appliance standards). We
recognize that the factors under each component may have a major impact on
energy and water use and liquid, gaseous, and solid residuals generation.
However, we have chosen to concentrate primarily on the second component. We
believe that we can obtain more reliable estimates of the influence which fac-
tors under this component have on resource use, residuals generation and con-
servation measures.
Although we intend to emphasize the second component we do not ignore the
other two. After organizing the household activities by function, we identify
the behavioral, physical and institutional factors which influence energy and
water use and the residuals generation. With this structure we critically
review the relevant literature to provide a basis for estimating use and gen-
eration rates and for assessing the influence, where possible, of the factors
on these rates. Then, conservation measures and estimates of their perform-
ance and cost are presented. We bring together resource use and residuals
generation rates and conservation measures in the context of the factors
which influence them, by utilizing two baselines or benchmarks developed for
single family residences. These baselines are identified as low and high
resource use and residuals generation households. Conservation measures are
-------
imposed on the baselines, direct costs to the households are calculated and
the relative attractiveness of the measures is determined in terms of the
cost/unit reduction in resource use or residual generation.
-------
SECTION 2
CONCLUSION
In meeting the objectives of the study, we have found it necessary, in
order to use literature estimates of residential resource use and residuals
generation, to provide a common basis or framework within which to view the
range of values of these estimates. We have devised an approach which puts
some perspective on the relationship between literature values of residential
energy and water use and gaseous, liquid and solid residuals generation,
potential conservation measures and various household functions. Benchmarks
or "Baselines" are constructed by specifying for the household functions
the characteristics which underlie use and generation rates. Conservation
measures are then imposed on these baselines and reductions and their costs
to the household are explicitly evaluated.
The following conclusions can be drawn regarding available literature,
the baseline method, and the results obtained with its use:
1. In the literature estimates of resource use (energy and water) and
of generation of liquid, solid, and gaseous residuals for different types of
individual housing units vary widely. Generally, the discussions which
accompany these estimates only hint at cause-effect relationships. Thus for
purposes of this study we summarize the estimates, while maintaining the dis-
tinction between high and low rates and interpret some of them in accordance
with our judgment.
2. Organizing the household by functions and associated activities bur-
dened the search for and application of use and residual generation figures,
but did provide an operational concept to assist understanding energy/mater-
ials/residuals flows, to identify possible points of conservation, and to
assess potential conservation measures.
3. An established literature on potential measures to reduce resource
use and residuals generation in households which includes cost and performance
estimates does not yet exist. We were required to review a wide variety of
materials (trade and professional journals, brochures, pamphlets, unpublished
reports, etc.). To interpret the estimates found in these sources and to
understand the implications of many of the reported values, and the effective-
ness and limitations of conservation measures we contacted building suppliers,
appliance manufacturers and utilities. In this search it became clear that
the physical, institutional, and behavioral factors which characterize indivi-
dual households and their environments have a significant impact on resource
use, residuals generation, and conservation measures. Therefore it became
-------
necessary to interpret use and residuals generation figures within a frame-
work of institutional/administrative, physical/technological, and behavioral
factors in order to analyze and assess conservation measures.
4. Constructing baselines provides a reasonable perspective on the rela-
tionship between use and generation figures and potential conservation
measures and permits estimation of their relative effectiveness (given the
various factors of influence). Even though we devised low and high use base-
lines only for new single family residences, the method should be applicable
to most any type of residential structure. However, in order to apply the
methodology to existing housing, the spectrum of conservation measures might
have to be broadened because retrofitting requires somewhat different technol-
ogies and clearly has different costs to households than is the case with new
housing.
5. In the baselines used in this study the differences between the high
and low use and generation rates are more a matter of the physical character
of the structures (e.g., amounts of insulation, efficiency of the heating
system, and the presence of resource using devices) than the behavioral diff-
erences of the occupants. We feel this limitation is necessary since usable
estimates of the response of households to resource price changes or to com-
prehensive conservation campaigns are not available. Therefore, most of the
conservation options chosen rely on physical changes in the structure or on
equipment rather than on changes (no matter how marginal) in the life style
of the residents. Reducing solid residuals generation, however, is a some-
what different matter because behavioral factors become dominant in all
reduction options.
6. The conservation measures (or combinations of measures) are rated on
the basis of cost per unit of reduction in resource used or residual generated
(e.g., $/l,000 gallons or $/10 Btu). However, since behavioral factors are
so important in reducing solid residuals, we have used a level of "inconven-
ience ," which depends to some extent on time, to rate potential measures.
7. Regarding reducing residential energy and water use, we conclude as
follows:
(a) Since heating and cooling, and water heating, make up the major
portion of residential energy use (approximately 80%) any conservation
measures should be first oriented toward reduction in these functions. Most
other reductions can be classed as incidental.
Given our high use baseline space heating conservation measures proceed-
ing from very modest addition of insulation to substantial increases in thick-
ness of insulation and inclusion of storm windows can reduce the fuel require-
ments by almost 60 percent. The effects of burner maintenance and lower
thermostat setting depend on what physical improvements have been made; the
contributions are small in the case of well insulated homes. High cooling
loads can also be reduced by improved insulation; in our case by 40 percent.
In the low use case (insulation according to FHA -73 standards) the reduction
of the space heating load can still amount to 55 percent for the best
-------
insulation, but the relative effectiveness (as measured by cost/unit of energy
saved) decreases; it is $2.48/10 Btu in the high use case, while $5.6/10
Btu in the low use case. But, for example, intermediate insulation, such as
an increase to 6 inches in the roof and additions of storm windows has a rela-
tive effectiveness of $0.57 and $1.92/106 Btu respectively. Thus, given the
current cost of natural gas to the consumer — an average cost in the north-
east of between $3/106 Btu and $4/106 Btu — only the very highest levels of
insulation would appear to be unreasonable for the low use case. The increase
in fuel prices will make the more expensive conservation measures attractive.
However, for those households which face decreasing block prices for fuel, the
increasing marginal costs/unit of energy saved will make the installation of
the last few inches of insulation less attractive.
Solar energy systems can provide a substantial portion of the heating and
cooling load. Housing with solar systems is generally very well insulated
(up to 24 inches of ceiling insulation and 5-5/8 inches of wall insulation).
Given a conservative estimate that a solar system could provide (for either
baseline) approximately half of the heating requirement at a cost of $10/106
Btu, the remaining fuel requirement would be 27.5 x 106 Btu/yr for the low
use baseline, and 53.0 x 106 Btu/yr, for the high use baseline. In the case
of cooling (the solar system augmented by some auxiliary equipment at a unit
cost of about $3,000), the annual cost would be $21/106 Btu if it provided 50
percent of the energy for cooling. For water heating few reductions in energy
can be expected in either baseline unless a flow through unit or a solar unit
is substituted for the more conventional storage water heater. Nonetheless,
the cost-energy savings ratios show that,given current fuel costs, all are
reasonably attractive measures — particularly in the case of high energy use.
(b) The greatest indoor water savings can be realized within the
bathroom function, because toilet and bathing are the most important water
using activities. In the low baseline the toilet accounts for 33 percent and
bathing 22 percent of indoor use. In the high case, the shares of indoor use
are 38 percent and 19 percent respectively. In calculating the possible re-
ductions for the baselines, the most reliable estimates of the decreased water
use are those for the toilet, since a decrease in the volume of water necess-
ary to flush is translated directly into savings. The estimates of both
shower and sink water saved are less reliable, because reduced flow rate does
not necessarily translate into a savings.
Remarkable reductions in water use can be achieved, some even with small
investments in hardware (such as dual flush mechanisms and low flow shower
heads) which use water more efficiently. Such a modification leads to about
30 percent savings for the high baseline at $0.36/1,000 gallons, and to about
20 percent savings for the low baseline at about $0.22/1,000 gallons. The modi-
fication composed of composting toilet (e.g., clivus multrum), air assisted
shower head, and recycling of gray water for lawn irrigation saves up to 92 per-
cent of the high baseline bathroom use at $4.1/1,000 gallons, and up to 55 per-
cent of the low baseline bathroom use at $10.8/1,000 gallons.
8. Regarding reducing residential generation of gaseous, liquid, and
solid residuals, it can be concluded:
-------
(a) gaseous residuals are only generated by those functions which
convert fuel to heat in residences. Since their contribution is very low (with
and without their reduction), residential housing does not influence signifi-
cantly air quality, given the assumption that neither coal nor solid residuals
are burnt. Therefore the reduction of gaseous residuals is only considered in
the context of reducing energy use.
(b) Since it is assumed in the liquid residuals baselines that none
of the water used indoors is consumed, the reduction in wastewater hydraulic
load is the water saved. The only measure which will have more than a mar-
ginal effect on the residuals is the modification (leading to the largest
water savings) in which all the residuals are put on the land. In case a gar-
bage grinder is used, its elimination has a substantial impact because its
contribution to the liquid residual is the largest single source,
(c) In a residential setting of single family homes with gardens,
composting organics together with garden wastes can provide the largest reduc-
tion of the total load. In the presence of garbage grinders, composting gar-
den wastes makes up the largest single reduction. Separating newspapers,
glass and metals can reduce the individual components significantly; but the
reduction of the total load is only significant in case these components are
recovered at a rate of 30 to 50 percent. Separating additional fractions of the
paper component should provide further reduction of the load.
-------
CHAPTER 3
RECOMMENDATIONS
1- Extension of Work Toward Behavioral Component; This study has not given
great emphasis to the impact of individual behavior on conservation. This is
due in part to the relatively low reliability of data needed to infer the
response of households to changes in resource prices and pricing policies (e.g.,
peak load pricing for water). Little exists which could be used in a study
like this. If it is desirable, however, to devise implementation incentives
which induce conservation, the response of households must be empirically
assessed. Schemes should be developed which effectively guide empirical
studies. Therefore it is necessary to initiate adequate programs to collect
the data from which operational behavioral models can be constructed.
2. Lack of Good Performance and Cost Data of Conservation Equipment; Even
though this area has become of so much concern, accessible data are largely of
low quality. The nonexistence of data is responsible in part for this situa-
tion, but also the lack of consistency and completeness in reporting existing
data. In general, performance data are more easily obtained than cost data;
but in this study we show that, especially in dealing with equipment applied
in areas which contribute marginally, but not insignificantly, to resource use
or residuals generation, the lack of data is noticeable. Often data provided
by manufacturers are more for the purposes of promotion than evaluation. A
well directed and wide ranging effort must be undertaken to collect consistent
and reliable performance and cost data.
3. Lack of Data; Clearly certain areas are not covered in the literature
because data have not been collected. Therefore, concerted efforts have to
be undertaken to collect resource use and residuals generation data at various
locations and seasons; otherwise it is impossible to evaluate relative effec-
tiveness of conservation measures. We feel that particularly water use and
liquid and solid residuals generation have not been explored to such an extent
that reliable estimates can be made given certain behavioral and physical
assumptions.
4. Literature Values and Their Inconsistencies; Data used in the study are
based solely on the review of literature on residential resource use and
residuals generations and on respective conservation measures. Some of the
areas have been covered extensively in the literature; others almost not at
all. But even in those areas which have been studied frequently the compari-
son of data is very difficult. Even though the data may be reported in a
complete way, cause-effect relationships cannot be identified. This often
leaves the reader unable to understand or explain the wide range found in the
reported figures. Sometimes the data are just incomplete. A typical example
8
-------
occurs in the literature on the solid residuals? figures might be given in
terms of composition C.%; Ibs) but without relation to climate, season,
and (socio-economic) areas of generation* Frequently composition is reported
only as a percentage and total residuals estimates are impossible. Even
though many people hold the view that literature reviews and data evaluations
have been done beyond justification, additional sorting and evaluation
of reported data is needed.
5. Studies of Retrofitting Residences for Conservation; Several studies
of retrofitting residences for energy conservation exist. Although studies
also have been done on water conservation and the reduction in liquid re-
siduals, they tend to be more descriptive than analytic, or they are outdated.
For solid residuals the number of adequate studies is even lower. Compre-
hensive and timely studies are needed for water conservation and liquid
and solid residuals reduction.
-------
SECTION 4
HOUSEHOLD FUNCTIONS AND FACTORS AFFECTING RESOURCE USE AND RESIDUALS GENERATION
The many activities which contribute to the routines of a household
are organized under nine functions. These functions and associated activities
are listed in Table 1 and their relationships to household material and
energy flows are diagrammed in Figure 1. The service functions of space
heating and cooling, water heating and lighting are each essentially one
activity. In the case of other functions such as kitchen, bathroom, washing
and cleaning, and living and entertainment, a variety of activities take
place.
TABLE 1. HOUSEHOLD FUNCTIONS AND RELATED ACTIVITIES
• Space Heating and Cooling
• Water Heating
• Lighting
• Kitchen
-food preparation
-cooking
-dish washing
• Washing and Cleaning
-clothes washing and drying
-house cleaning
• Bathroom
-toilet
-bathing
-sink
-personal upkeep
Living and Entertainment
-audio visual
-hobby
Outdoors
-garden/yard
-recreation
-other
Maintenance
-automotive
-upkeep, repair
Activities related to the functions kitchen, bathroom, and living and
entertainment tend to be room specific; other functions such as washing and
cleaning occur throughout the living space. The maintenance function occurs
both indoors and outdoors, and consists of repair and upkeep of appliances,
the heating, lighting, and water systems, house painting and auto repair.
The outdoor function involves landscaping and other yard and garden activities
including outdoor entertainment and recreation.
Table 2 summarizes for each function, which resources are used and
which residuals generated. Almost all of the functions use energy and the
majority use water. Liquid residuals are generated by several functions
and three sources of gaseous residuals are identified. Several of the
functions generate solid residuals. However, as a matter of convenience in
10
-------
r
Service Functions
Heating
a
Cooling
Woter Heating
Lighting
Energy, Woter, Materials
Outdoors runctiont
Examples:
Indoors: Toilets
Outdoors: Irrigation
Collection
a
Treatment
Treatment) Release
» Separation
Collection X \
*• a f 1
Disposal
Recycle
Release
Collection
•*• a
Treatment
o
Recycle
Release
to Recharge
FIGURE Is HOUSEHOLD FUNCTIONS,RESOURCE CONSUMPTION AND RESIDUALS GENERATION
-------
TABLE 2. FUNCTIONS TO BE CONSIDERED IN TERMS OF
RESOURCE USE AND RESIDUALS GENERATION
Resources
Residuals
Energy Water
Liquid Solid Gaseous
Space Heating
& Cooling
Water Heating
Lighting
Kitchen
Washing
& Cleaning
Bathroom
Living
& Entertainment
Outdoors
Maintenance
X
X
X
X
X
X
X
(X)
X
X
X
X
X
X
X
X
12
-------
organizing the functions, all indoor solid residuals are assigned to the
kitchen function and the solid residuals generated in landscaping, gardening
and maintaining the exterior of the residence are assigned to the outdoors
function.
Factors which affect the use and generation rates appear in Tables 3
through 6. These tables list by resource (or residual) and by household
function the administrative/institutional, physical/technological, and
behavorial factors which influence the use and generation rates. At the
bottom of each table a row (or set of rows), which is labeled General,
contains items on price and pricing policy. We recognize that price changes
and pricing policy can act as powerful incentive mechanisms and in an effort
to make the tables complete, if not exhaustive, we have made them part of
the list. However, recall from Section 1 that we intend to assume fixed
factor prices in this study. In subsequent sections we will discuss the
other factors and consider how those under the physical/technological
component in particular are associated with energy and water use and with
liquid, solid and gaseous residuals generation.
13
-------
TABLE 3. FACTORS AFFECTING ENERGY USE
Function
Administrative &
Institutional
Physical &
Technological
Behavioral
Space Heating
and Cooling
-Building Codes
(ASHRAE 90-75)
-ordinances or
standards which
may affect the
public acceptance
or availability
of energy saving
devices
-research in
energy conser-
vation and
development of
new systems
-financial incen-
tives affecting
designs or type
of insulation,
etc.
-bank mortgage
practices
-insulation
-storm windows/
door and win-
dow weather
stripping
-shape
-orientation
-landscaping
-mounding
-awnings
-Venetian blinds
-curtains
-HVAC size
-waste heat use
-type and fuel
of system:
electrical resis-
tance; gas/oil;
solar
-number of control
points for temper-
ature setting
-thermostat
timer
-color of walls
and roof of
residence
•thermostat
setting
•heating of
unoccupied
rooms
use of curtains
and/or Venetian
blinds for win-
dow insulation
•proper use of
flue
•maintenance of
HVAC system
Water Heating
-ASHRAE design
standards
-insulate hot -water heater
water pipes temperature
and storage setting
tank -maintenance of
-distance between furnace
water heater and
major uses
-central system
in multi-family
housing
-ratio of system
capacity to house-
hold use
14
(Continued on next page)
-------
TABLE 3 (CONTINUED)
Function
Administrative &
Institutional
Physical &
Technological
Behavioral
Water Heating
(continued)
-type of heating
unit
-type of pilot
light
-quick recovery
option
-separate (or
booster) water
heater
-solar water
heater
Lighting (in
the whole house)
-type of light-
ing units
-selection of
lighting level
-lighting prac-
tices
Kitchen -design standards
for ranges,
refrigerators,
freezers, and
other kitchen
appliances
-type of range
-type of dish-
washer (if any)
-type of stove
and over pilots
-type of refri-
gerator/freezer
combination
-frequency of
use of range
-frequency of
use of garbage
grinder
-frequency of
use of dishwasher
-use of drying
system in dish-
washer
-temperature set-
ting of refriger-
ator
-use of other appli-
ances
Washing/Cleaning -design standards
for washing
machines,
dryers, vacuum
cleaners, and
other appliances
-type of wash-
ing machine
-frequency of
use of washing
machine
-frequency of use
of dryer
-choice of deter-
gent
(continued on next page)
15
-------
TABLE 3 (CONTINUED)
Function
Administrative &
Institutional
Physical &
Technological
Behavioral
Washing/Cleaning
(continued)
Bathroom
Living and
Entertainment
Outdoors
-type of dryer
(gas, with/
without pilot
light; elec-
tric)
-type of iron
-type of vacuum-
cleaner
-type of floor
polisher
-individual heat-
ing systems
-hair dryer
-heat lamp
-type of tele-
vision
-radio/stereo
-presence of
swimming pool
with pump and
heating system
-frequency of
use of iron
-frequency of
house cleaning
-temperature of
bathing water
-frequency and
length of bathing
and/or showering
-frequency of use
of appliances
-frequency of use
of TV and radio/
stereo
-energy-consuming
hobbies (sewing,
wood-working ,
etc.)
-use of pool heat-
ing system
Maintenance
General
-price of energy
(gas, oil, elec-
tricity)
16
-------
TABLE 4. FACTORS AFFECTING WATER USE
Function
Administrative & Physical £
Institutional Technological Behavioral
Space Heating
and Cooling
-water heater
design standard
-hot water pipe
insulation
Lighting
Kitchen
Washing and
Cleaning
Bathroom
Living and
Entertainment
Outdoors
-appliance stan-
dards
-ordinance on
garbage grinding
-appliance stan-
dards
-ordinance on
water reuse
-ordinances and
standards on
bathroom fix-
tures and appli-
ances
-ordinance on
water use
-ordinance on
water recycling
-zoning ordinance
on lot size
-building code
-type of sink
-type of nozzle
-type of faucet
and control
valve
-dishwasher
-garbage grinder
-washing machine
model
-bath tub size
-type of shower
head
-type of toilet
-gray water recy-
cling system
-type of faucet
and control
valve
-type of lawn
sprinkler sys-
tem
-gray water re-
cycling system
-rainf a 1 I/runoff
storage and
control system
-type of land-
scaping
-swimming pool
-frequency of
dishwasher use
-frequency of
garbage grinder
use
-frequency of
washing machine
use
-laundromat use
-frequency and
duration of
bathing and
showering
-frequency of
toilet flushing
-frequency of lawn
sprinkling
-practice of wash-
ing of impervious
areas
17
(Continued on next page)
-------
TABLE 4 (CONTINUED)
Administrative & Physical &
Function Institutional Technological Behavioral
Maintenance -ordinance on -type of nozzle -frequency of
water use and hose for car washing
car washing "control of leaks
General -price of water
-metering
-sewer charges
-other ordinances
and regulations
affecting water
use
18-
-------
TABLE 5. FACTORS AFFECTING GENERATION OF LIQUID RESIDUALS
Function
Administrative &
Institutional
Physical &
Tecnnological
Behavioral
Space Heating
and Cooling
Water Heating
Lighting
Kitchen
-ordinance on
garbage grinders
-ordinance on con-
stituents of deter-
gents and other
cleaning compounds
-garbage grinder
-use of phosphate
free detergent
-selection of fresh
or preprepared
food
-frequency of use
of garbage grinder
-amount of food
waste and disposal
practices
Washing and
Cleaning
-type of washing -floor covering
machine preference
-type of detergents
used
-washing and clean-
ing practice
Bathroom
-Clivis Multrum -frequency of
waterless toilet bathing
-Ecolet waterless
toilet
Outdoors
-permit (require-
ment) to use gray
water
-gray water recy-
cling system
-type of landscape
vegetation
Maintenance
-incentives for
recycling
waste oil
-restrictions on
dumping waste oil
-auto maintenance
practices
-used lubricating
oil disposal
practice
General
-price of water
-pricing policy
(e.g. peak load
pricing)
19
-------
TABLE 6. FACTORS AFFECTING SOLID RESIDUALS GENERATION
Function
Administrative &
Institutional
Physical &
Technological
Behavioral
Heating and
Cooling
-coal fired heating
system
Water Heating
Lighting
Kitchen
(and storage)
-durability of light
bulbs
-ordinance on -garbage grinder -eating, drinking
garbage grinder -storage space for & related pur-
-food products recyclable mater- chasing habits
offering ials and con- -frequency of gar-
tainers bage grinder use
-compactor -use of compactor
-reuse of packaging
material
Washing and
Cleaning
Bathroom
Living &
Entertainment
Outdoors
Maintenance
-purchase of news-
papers (and leaving
them at home)
-collection of maga-
zines and journals
-frequency of home
entertainment
-ordinance on -on-site compost _choosing Of mater-
compost heaps heap .„. . ials to be Put on
^ * -composition of gar- compost heap
den regarding type
of trees and lawn
-standards on -durability of -throw away-repair
durability of goods habits
g00ds -selecting appliances
to be thrown away
or repaired
20
(Continued on next page)
-------
TABLE 6 (CONTINUED)
Function
Administrative &
Institutional
Physical &
Technological
Behavioral
General
-ownership of
dwelling unit
-ordinance on
use of items
made at least
partially of
recycled mater-
ials
-support of re-
cycling center by
municipal govern-
ment
-separate collec-
tion services of
materials (type)
and their adver-
tisement
-ordinance on man-
datory source sepa-
ration
-"bottle bill"
legislation
-user charge sys-
tem
-factor prices of
recycled materials
-resource prices
-scavenger ordinance
-recycling centers
in neighborhood
and/or community-
wide
-housing charac-
teristic (type,
age, size, room &
space distribu-
tion)
-central storage
facility for
recyclable mater-
ials in MduH*
-chutes {MduH) for
direct discarding
materials
-recycling centers
in neighborhood
and/or community-
wide
-inclination
to reduce
residuals
generation
through pur-
chasing and
use habits
-investment of
"time" in re-
cycling acti-
vities
-amount of time
of family at
home
*MduH = multi-family dwelling unit housing.
21
-------
SECTION 5
HOUSEHOLD FUNCTIONS, RESOURCE USE, AND RESIDUALS GENERATION
Each of the household functions identified in Section 4 is discussed here
in terms of water and/or energy use and residuals generation. Service functions
that comprise only one activity are discussed first, followed by those functions
comprised of a variety of activities.* The discussions consist of reviews of
those studies concerned with the particular functions that report data on
resource use and residuals generation. The two exceptions are heating/cooling
and lighting. Because of the high energy requirements of heating/cooling
and the great variability of energy needs in different parts of the nation
in a variety of residential structures, a method is presented for calculating
energy use as a function of type of structure, construction materials, struc-
tural soundness, and climate. Lighting is discussed only briefly because it
uses such a small portion of the total energy in a residence.
SPACE HEATING AND COOLING
Space heating and cooling is the household function which requires the
greatest amount of energy. In a typical single-family home in the northeast
with 5500 heating degree days and 400 cooling hours per year, over 65 percent
of the energy used (approximately 77 million Btu) will be devoted to this func-
tion (4). In this section we present the ASHRAE method for calculating heating
and cooling loads, the resultant energy requirements (5), and the residuals
generated as a function of type of structure and climate.
Heating and Cooling Load Tables
Tables were constructed for a variety of typical residential structures
to show heat loss per sq ft per degree day, and cooling load per sq ft per
cooling hour.
Tables were developed for four types of residential dwellings.t
1. Single Family, one-story, unattached
2. Single Family, two-story, unattached
3. Attached Split-level Townhouses
4. Three-story, Low Rise apartments.
* Appendix A contains mass and energy flow charts and a more detailed presen-
tation for each function.
t See Appendix B for method of heat loss calculation.
22
-------
For each of the construction types three different wall materials (i.e., wood,
brick veneer, and aluminum siding) were considered initially.* However, because
the heat loss coefficients for the three wall materials vary only a few percent
one set of coefficients which are an average of wood and brick veneer is used.
Five levels of thermal soundness are also considered.
1. Uninsulated, no insulation on walls, floor or roof. Single windows.
2. FHA *65,t enough insulation to comply with the 1965 FHA minimum
property standards for federally insured homes.
3. FHA '73, enough insulation to comply with the 1973 FHA minimum pro-
perty standards for federally insured homes.
4. ASHRAE 90-75, enough insulation to comply with ASHRAE standards for
heat loss.
5. Best, 24" insulation in the ceiling, 5 5/8" of insulation in walls
(requires 6" studs), 2" of insulation around foundation, and storm
windows.T
Table 7 contains the complete array of insulation options. For each struc-
ture at each level of thermal soundness, heating load and cooling load were
calculated (Tables 8 and 9).**
The tables were constructed assuming a winter indoor temperature of 65°F
and summer indoor temperature of 75°F. The values for the 20 cases in each
table have units of Btu/sq ft of floor area heated (or cooled) per degree
day (or cooling hour). For reasons explained in Appendix B the cooling load
tables have two parts, one for an average outdoor temperature of 90°F and the
other for a temperature of 85°F. In an example below, use of both the heating
and cooling tables in conjunction with average degree days and cooling hours
for the northeast is demonstrated.
Computing Fuel Use and Emissions for Heating and Cooling
A one-story, single family house with 1,500 sq ft of living space construc-
ted according to FHA "65 standards loses about 25,650 Btu/degree day (1,500 sq
ft x 17.1 Btu/sq ft/degree day), when the indoor temperature is kept at 65°F.
Multiplying the heat loss by 5000 degree days gives an annual heat loss of
128.25 x 106 Btu. If the residence is equipped with a gas forced air heating
system (conversion efficiency of 75 percent) the total fuel requirement will be
128.25 x 106 Btu/yr * (1,040 Btu/cu ft x 0.75) = 164.42 x 103 cu ft of gas.
* These wall types represent construction characteristics reported in Charac-
teristics of New Construction. These types encompass most of the existing
stock of houses as well as new construction.
t See Appendix C for summary of regulations.
f Note; We designed our houses with a combined roof/ceiling, as given in
Thermal Design of Buildings.
** The details of the calculations are contained in Appendix B.
23
-------
TABLE 7, INSULATION IN STRUCTURES
None
Single Family
1- story
Wall
Roof
Window Single
Floor
Single Family
2-story
Wall
Roof
Window Single
Floor
Townhouse
9 Row
Wall
Roof
Window Single
Floor
3- Story
Low Rise
Wall
Roof
Window Single
Floor
FHA '65
-
1"
Single
1 1/2"
-
1"
Single
1 1/2"
1"
2"
Single
-
—
1"
Single
-
FHA '73
1-1/2"
3"
Single
2".
1-1/2"
3"
Single
2"
3"
5"
Single
1 1/2"
2"
3"
Single
1 1/2"
ASHRAE 90-75
3 5/8"
4"
Single
2"
3 5/8"
4"
Single
2"
1 1/2"
5"
Single
2"
3 5/8"
4"
Single
2"
Best
5-5/8"
24
Storm
2"
5 -5/8"
24
Storm
2"
5-5/8"
24
Storm
2"
5-5/8"
24
Storm
2"
24
-------
TABLE 8. HEAT LOSS — BTU/SQ FT/DEGREE DAY
Single Family
1-story
Uninsulated FHA '65 FHA '73 ASHRAE 90-75 Best
21.0
17.1
11.0
9.6
7.0
Single Family
2-story
19.2
17.3
11.2
9.7
7.0
Townhouse
Split Level
16.8
12.0
8.2
9.2
6.7
Low Rise
3-story
10.8
10.8
6.7
6.2
TABLE 9. COOLING LOAD FOR AVERAGE OUTDOOR TEMPERATURE 90°F*
UninsulatedFHA '65FHA '73ASHRAE 90-75Best
Single Family
1-story
40
35
27
24
Single Family
1-story
35
31
25
22
Units — Btu/sq ft/cooling hour.
19.4
Single Family
2- story
Townhouse
Split Level
Low Rise
3-story
36
24
19
COOLING LOAD FOR
Uninsulated
33
19
18
AVERAGE
FHA
27
15
14
24
16
14
19.9
12.1
10.5
OUTDOOR TEMPERATURE 85 °F*
'65 FHA '73
ASHRAE 90-75
Best
17.6
Single Family
2-story
Townhouse
Split Level
Low Rise
3- story
31
21
17
29
17
16
24
14
13
22
14
13
18.1
11.3
10.6
25
-------
In order to translate the fuel requirement into emissions the U.S. EPA-conver-
sion factors (6) (see Table A-5) are used. Total emissions are:
Particulates
SO2
SO 3
CO
Hydrocarbons
NO2
If the calculations are to be done for a different region of the country
an adjustment can be made on the basis of the ratio of degree days. For
example, the average number of degree days per year in Denver, Colorado is
6200. Thus for the same single family house in Colorado, heat loss would be
160 x 106 Btu/yr (128.25 x 106 Btu/yr x (6200/5000) with comparable increases
in fuel use and residuals generation. Determining the effect of changing
the thermostat setting is done on the same principle using conversion ratios
found in Table B-3 for various combinations of thermostat setting and average
outdoor temperature. Thus if the thermostat were turned up to 70°F and the
average outdoor temperature were 42°F the heat loss would be 153 x 106 Btu/yr.
Energy requirements for cooling are computed in a similar fashion using
the cooling load table in conjunction with average annual cooling hour values
and average outdoor temperatures. However, with electric cooling it is not
necessary to calculate air emissions since they occur at the power plant.
With average outdoor temperatures of 85°F during the summer and an average of
400 cooling hours in the northeast, the single family house with central air
conditioning will have a total cooling load of 21 x 106 Btu (35 Btu/sq ft/
cooling hour x 400 cooling hours x 1,500 sq ft). This is a little less than
20 percent of the heating load.
WATER HEATING
Residential water heating utilizes about 15 percent of the total residen-
tial energy consumption for the nation, accounting for about 3.9 (1012)Btu's
in 1970 (7). In a typical single family house in the Northeast the water
heater represents about 18 percent of the total energy requirement (4). This
makes water heating the second most important residential energy consumption
activity. Virtually all dwelling units that have plumbing also have hot water,
thus future growth of energy consumption for this function depends primarily
on population growth and growth in the per capita use of hot water.
The range of energy requirements for heating water is presented for elec-
tric, gas, and oil units along with the resultant air emissions. The results of
studies on estimating hot water uses are also discussed and reasons for the
wide variations in estimates are offered.
26
-------
Energy Requirements, Water Use and Residuals
Generation for Water Heating
Table 10 presents the energy requirements and the water use for the water
heating function. These data indicate that daily per capita direct energy
requirements range from less than 8,000 to almost 30,000 Btu's. Minimum and
maximum values for electric heaters are lower than for gas heaters. This dif-
ference may in part reflect incompatibilities in the data sources.* However,
despite the difficulty in comparing data from different sources, there is a
real difference in the direct energy consumption between electric and fossil
fuel heaters, due primarily to the energy losses involved in the combustion
and heat transfer for the fossil fuels. Under current ASHRAE guidelines (13)
a gas storage heater designed to supply 80 gallons/day at 140°F and a water
temperature rise of 80°F would require about 26,000 Btu/day more than a com-
parable electric heater (neglecting the substantial conversion losses at the
power plant). This is a difference of 43 percent. With a pilot-less igni-
tion (usually electric) the difference would about 17,000 Btu/day. How-
ever, if average fuel costs are considered, the electric heater is about 4.1
times as expensive to operate.t
Quick Recovery Electric Water Heaters—
Some electric water heaters feature "quick recovery" heating elements
which allow for more rapid heating after the stored water has been depleted.
These heaters draw about 4,500 watts as opposed to 2,500 watts for standard
heaters, and reportedly increase energy consumption by about 14 percent for
typical use (9). However, the rapid recovery heater would require less stor-
age for any given demand, and the economics for the consumer depend upon the
trade-off between storage costs and the additional energy costs.
Hot Water Use--
Residential hot water use can be estimated in two ways. First, the
reported energy consumption can be converted to an implied water use by
making explicit assumptions as to thermal efficiency and water inlet and out-
let temperatures. A second approach is to attempt to calculate the hot water
use from estimates of the individual water consumption for various activities
for given water temperatures. The first approach was employed in deriving
the estimates in Table 10. These estimates place per capita hot water use
at between 9 and 27 gallons/day, if a 140°F heater outlet temperature is
assumed. Estimates of individual activity use of the hot water are presented
in Table 11. These are intended to give ranges of normal household use and are
The range reported for electric heaters is based on data provided by Boston
Edison (10). The values for gas heaters are based on estimates by Hittman
Associates (12) for different dwelling types and household sizes. These
data agree closely with the range of regional averages reported by the
American Gas Association (8).
Based on national average prices of $1.42/106 Btu for gas and $8.29/106 Btu
for electricity in 1974, as reported in American Gas Association (8).
27
-------
TABLE 10. WATER HEATING ENERGY REQUIREMENT AND WATER USE
(UNIT/CAPITA/DAY)
Energy Requirement-—
(Btu)
Y2,5
gas heater -
pilot
gas heater -
electric.
ignition^-
electric
heater
oil
heater
electric
NA
X
7,900-
19,800
X
gas
17,900-
29,600
13,500-
27,200
NA
NA
oil
NA
NA
NA
13,500?
27,200^
UlfcJ J.J.CU Well.*:
(gal)
13.1-26.
13.1-26.
9.5-23.
13.1-26.
IJ. UtJt:
5
5
7
5
1. Direct energy consumption. Energy loss in power plant conversion is
ignored.
2. Total of hot water use of household activities. Should not be added
to water use of other activities in computing total water use.
3. Calculated from estimate with pilot light by assuming heat loads
of 9,600 Btu/day for pilot light.
4. Assumed to operate at same efficiency as gas.
5. Assumed hot water temperature = 140°F, average inlet temperature
60°F, efficiencies: electric = 0.80, gas and oil = 0.65.
Notes: Where data is given only in units/appliance, conversion to per
capita values based upon 3.5 persons/dwelling unless otherwise
specified by source.
NA = not applicable; X = data not available.
Sources: -American Gas Association (8)
-Edison Electric Institute (9)
-Boston Edison (10)
-Hittman Associates (11)
-Hittman Associates (12)
28
-------
TABLE 11. ESTIMATED HOT WATER USE BY ACTIVITY
Total Water Hot Water Frequency/ Hot Water Use
140° outlet temperature
aath & shower
dishwasing :
machine
hand
laundry :
hot cycle
warm wash/
cool rinse
cleaning
other (personal
upkeep, etc.)
10-50
10-17
8-14
25-60
25-70
2
1-10
100°F
140°F
110°F
120°F
100 °F wash
60°F rinse
120°F
100°F
5-25
10-17
5-9
19-45
5-12
1.5
.5-5
.5-1.0
.25-. 5
. 30- . 5
0-.5
0-.5
.1-.2
1
2.5-25
2.5-8.5
1.5-4.5
0-22.5
0-6.0
.1-.3
.5-5
120° outlet temperature
bath & shower
dishwashing :
machine
hand
laundry :
hot cycle
warm wash/
cool rinse
cleaning
other (personal
upkeep, etc.)
10-50
10-17
8-14
25-60
25-70
2
1-10
100°F
120°F
110°F
120°F
100 °F wash
60 °F rinse
120°F
100°F
6.7-33
10-17
6.7-11.7
25-60
6.7-16
2
.7-6.7
.5-1.0
.25-. 5
.30-. 5
0-.5
0-.5
.1-.2
1
3.3-33
2.5-8.5
2-5.8
0-30
0-8
.2-. 4
.7-6.7
Notes: Assumed water inlet temperature 60°F. It has been assumed that fre-
quency of use is independent of volume of use.
29
-------
based on the available literature. For a 120°F water outlet temperature a
low water use household, which hand washes dishes, does all laundry at a
laundromat, and uses the minimum values listed, would employ an average of
6.2 gpcd. A high consuming household with a washing machine and automatic
dishwasher, and utilizing the maximum values listed would require almost 80
gpcd. The latter figure is undoubtedly unrealistic as an average over an
extended period of time (30 gpcd is a more reasonable figure), but it indi-
cates the high energy using potential inherent in a modern home equipped with
common appliances.
Air Emissions—
The residuals indicated in Table 12 were obtained by applying EPA emis-
sion coefficients (6) to the energy use data (Table A-5), and are thus
strictly proportional to fuel use for any particular fuel type. Since water
heating is responsible for only one-sixth as much energy use as space heating,
and relies mostly on natural gas and electricity, the contribution of air
pollutants from water heating is a relatively small proportion of the total
residential contribution.
LIGHTING
Energy used for lighting comprises about 15-20 percent of the lighting/
appliance energy load and about one to two percent of the total residential
energy load. An average value for energy used in home lighting is 876 kwh/
yr,though, depending on the household, it could range anywhere from 500-
1,750 kwh/yr. It neither uses substantial amounts of energy nor produces
significant residuals.
KITCHEN
The kitchen function includes three major activities; food storage and
preparation, dishwashing, and storage and disposal of solid residuals. These
activities generally involve the use of "appliances." The impact of the fol-
lowing appliances on both resource use and residuals generation* are considered
as parts of the Kitchen function.
Food Storage and Preparation
-refrigerator/freezer (E)
-separate freezer (E)
-stove/oven (E)
-sink (W, WW, LR)
E = energy consumption at point of user; W = water consumption; WW = amount
of wastewater; LR = characteristics of liquid residuals (in wastewater);
SR = solid residuals; and GR = gaseous residuals.
30
-------
TABLE 12. RESIDUALS GENERATIONS ASSOCIATED WITH WATER HEATING
Air Emissions (Ib/capita/day)
gas
heater
-pilot
gas heater
-electric
ignition
electric
heater
oil
heater
particulates
3.2(10~**)*
-5.4(10~**)
2.4(10"**)*
-4.8(10~**)
NA
9.6(!0"**)t
-19.2(10"**)
so2
1.0(10~5)*
.77(10~5)*
-1.50(10~5)
NA
.03(10~5)t,:
-.07(10"5)
NOX
1.7(10~3)*
-2.8(10~3)
1.3(10~3)*
-2.6(10~3)
NA
f 1.15(10~3)t
-1.30(10~3)
CO
3.4(10"")*
-5.6(10~**)
2.6(10~**)*
-5.2(10"**)
NA
4.8(10~**)t
-9.6(10~**)
* 1 cu ft natural gas = 1,050 Btu.
t 1 gal fuel oil - 140,000 Btu.
f Assumed sulphur content 2.5 percent by weight.
31
-------
Dishwashing
-sink for manual dishwashing (W, WW, LR)
-automatic dishwasher (W, WW, LR)
Storage and Disposal of Residuals
-garbage grinder (E, W, WW, LR)
-compactors (E, SR)
-chutes (gravity or vacuum) (E, SR)
-storage bins for mixed and/or separated solid residuals (LR).
Energy Use and Gaseous Residuals Generation
The ranges of resource use and residuals generation in the kitchen, identi-
fied in the literature or derived from various sources, are summarized in
Tables 13 and 14. The 1970 saturation levels for each appliance and those
projected for 1990 are shown in the table and indicate the importance of each
appliance in the household.
Energy Use—
The consumption and operating requirements of refrigerators, freezers,
ranges, and dishwashers are shown in Table 13, columns 1 and 2.* The probable
distribution of other electrical appliances in households with different energy
use levels are indicated in Table 14. All the yearly values of use (kwh/yr)
are based on the literature.
Freezers, particularly the frost-free version, are the most energy-
intensive appliances in the kitchen. The saturation figures (Table 13) sug-
gest that there are not many in use because they are expensive to buy and to
operate. In addition, the increasing size of refrigerator/freezer combinations
limit the need for an additional freezer. Another factor is the lack of space
in apartment buildings to accommodate a freezer. Manual defrost freezers,
frost-free refrigerator/freezer combinations, and stove and oven units consti-
tute a group of similarly intensive energy appliances. Manual defrost refri-
gerator/freezer units and dishwashers usually utilize less than half as much
energy as a stove or frost-free refrigerator.
Although frost-free refrigerators may consume as much as 30-60 percent
more energy than manual units, 70 percent of the working units are expected
to be frost-free designs in 1990. Currently 40 percent of the units are of
this type (14). The lower kwh/yr figure for manual units, however, may be
somewhat unrealistic; energy consumption rises as soon as ice begins to accumu-
late within the unit, so that irregular defrosting could lead to an energy
Garbage grinders are not discussed in the section on energy consumption
because their use of electricity is negligible.
32
-------
TABLE 13. APPLIANCES IN KITCHEN AND THEIR RANGE OF RESOURCE USE AND RESIDUAL GENERATION
Refrigerator/ Frost Free
Freezer Manual
Separate Frost Free
Freezer Manual
Range (stove/oven)
Sink
D1£nwaShlliy Manual
Garbage Grinder
Storage Bins
Refuse Compactor***
Energy*
kwh/yr 10 Btu/cap/day
750-1,790 2.0-4.8
460- 728 1.2-1.9
1,761-1,985 4.7-5.3
1,195-1,320 3.19-3.5
1,142-1,550 3.05-4.14
(2,300-3,100) tt
-
322-380 .86-1.02
- -
9.9-30 .03-. 05
-
60
Waterf
and
Wastewater % Saturation t
(gpcd) LR SR 1970 1990
- 98** 120
28 „*
— — — 46
(21)
- - 41 75
(28)
2.7-lS.ott - >100 >100
(9.9) g
1.1-6.0 S" 19
1.1-4.6 H (34)
en
.8-4.0 5?
&
' ' i —
CD
&
OJ
u>
* Assumption of 3.5 people per household for per capita energy consumption figure; energy figures
neglect conversion loss at power plant; energy use for hot water heating is accounted for in
Water Heating.
t Evaporative losses are neglected; per capita figures are based on the family sizes encountered in
sampling programs of the authors (see "Bathroom and Bedroom").
(continued)
-------
TABLE 13. (CONTINUED)
f Figures are based on Project Independence (local and regional differences are documented in the
literature); the figures in parentheses indicate the figures for Southern California.
** 40 percent of the units in operation today, and 70 percent of the ones in operation in 1990 are
of the frost free feature.
tt The figures in parentheses give the consumption figures of gas ranges.
ff 18.0 and 9.9 gpcd include bathroom sinks.
*** Only one source of reference.
u>
-------
TABLE 14. APPLIANCES IN KITCHEN FOR HYPOTHETICAL LOW, MEDIUM AND HIGH ENERGY
HOUSEHOLDS.* {BTU IN MILLIONS/YEAR)
[Low Btu
1
Range 4 . 0
Refrigerator 2.5
(manual)
Coffeemaker .5
Toaster . 1
Medium
Range
Re frige rator/
Freezer
Coffeemaker
Frying Pan
Toaster
Btu
4.3
4.0
.5
.3
.1
High
Range
(self cleaning)
Refrigerator/
Freezer
Freezer
Dishwasher
Coffeemaker
Frying Pan
Toaster-Oven
Broiler
Trash Compacter
Toaster
Btu
4.8
4.4
5.0
1.2
.5
.3
.3
.3
.2
.1
Ul
The Btu-values are typical values for these appliances as provided by manufacturers.
-------
consumption as high as that of a frost-free unit. Side-by-side refrigerator/
freezer combinations are inefficient; they use approximately 18 percent more
electricity than comparable top-freezer models (15).
Gas refrigeration units are no longer sold in this country; however, some
units are still in operation. In 1968, there were four million gas units,
compared to 57.6 million electric units. A gas refrigerator uses an equivalent
of 4,102 kwh/yr compared to 1,270 kwh/yr for electric units (neglecting
the conversion losses at the power plant) (16).
The average size of refrigerators increased by about one-thrid of a cu ft/
yr during the 1960's. Recently, the rate of increase has dropped to one-sixth
of a cu ft/yr because of the limits imposed by current building standards. In
1970 the average size was 13 cu ft; it is now 14 cu ft (14).
The saturation level of ranges (stove and oven combined for our purposes)
has been above 90 percent in the past 20 years; currently it is 97 percent.
Both gas and electric ranges are still sold, but sales of electric ranges
began to outnumber sales of gas ranges during the mid-19601s, even though gas
ranges are cheaper to buy and cheaper to run (in terms of energy use costs).
The number of electric units in operation is now larger than the number of
gas units. Only on the West Coast is the number of gas ranges sold and in
operation greater than the number of electric ranges.
The various sizes of gas and electric ranges, along with cooking habits,
account for variations in energy consumption by these appliances. The Ameri-
can Gas Association, for example, makes the distinction between house ranges
and apartment ranges. House ranges are estimated to consume on the average
10.5 million Btu/yr (3,080 kwh/yr) compared to 8.8 million Btu/yr (2,340 kwh/
yr) for apartment ranges.
Most of the energy consumed by the operation of dishwashers is attributable
to hot water demand. Dishwashers use eight to nine percent of the central hot
water supply in the home. Up to 16 gallons of hot water of the central hot
water system (about 120°F-140°F) are used per cycle. In models with "sani-
wash" features the water is further heated up to 150°F-155°F. The heating/
drying cycle is the second largest energy consuming factor. Eliminating it
would save about 30 percent of the energy used in a dishwasher (14).
Residuals Generation—
There are no significant amounts of gaseous residuals emitted from the
residence by the kitchen appliances. There are some implied power plant emis-
sions associated with the use of electric appliances, but they are not con-
sidered in this study. The gas stove and gas refrigerator do convert fuel in
the residence, but the products of the conversion process are unimportant as
residuals.
Water Use and Wastewater and Liquid Residuals Generation
Sinks, dishwashers, and garbage grinders are the water users in the kit-
chen. Neglecting losses due to evaporation in food preparation, the wastewater
36
-------
generated is equal to the amount of water used at these points minus any
recycling which may occur. All water consumption figures in Table 13 are
based on references discussed in more detail in the section on the bathroom
(see below). Most of the values appear to be reasonable and are consistent
among the references. Dishwashing (manual or automatic) is the greatest water
user in the kitchen. Use of a garbage grinder also consumes substantial amounts
of water as shown in the table. Food preparation is included in the category
"sink," since there are no data on this water use activity alone.
The fange of water use estimates for each of the appliances is greater
than four-fold. But it should be understood that the ranges are not meant to
reflect limits. There are derived from literature values based for the most
part on small samples (17). They are not lower and upper bounds.
The greatest source of liquid residuals in the kitchen is the garbage
grinder. As shown in Table 15 over half of the BOD5 and suspended solids
result from this appliance. Use of the sink does contribute somewhat less
than half of the BODs and a very small portion of the suspended solids.
Organics from the dishwasher are at least an order of magnitude less than
either the garbage grinder or sink. As sources of nutrients the appliances
are comparable and as will be shown below, they supply amounts of total nitro-
gen and total phosphorus in the same range as washing machines.
Solid Residuals Generation
The kitchen function includes the storage and disposal of solid residuals
generated in all indoor household functions. These solid residuals include:
(a) lint, inorganics from sweeping the floor, vacuuming, etc; (b) paper, glass,
plastics, textile, rubber, leather products and other incidentals; (c) paper,
bottles, cans and other miscellaneous incidentals, such as ashes from fire-
places; and (d) ash residuals from individual heating systems fired with coal
and wood.
The values shown in Table 16 (derived in Appendix D) are based on an aver-
age household of 3.2 persons (average U.S. family size) because the per capita
generation data (used as multiplier for the percentage ranges of each component)
were derived from a nationwide material flow balance. A low and a high esti-
mate is provided for three cases: (i) combined disposal of all solid wastes;
(ii) separation of glass and metals from paper and other wastes; and (iii) use
of a garbage grinder. By and large, paper is the most important component of
solid waste accounting for over 30 percent by weight in most cases. Paper is
followed by food wastes except when a grinder is used. Glass is also important,
as is metal. The other constituents are quite negligible.
WASHING AND CLEANING
The washing and cleaning function is composed of two major activities —
clothes washing and drying, and room cleaning. The clothes washing and drying
activities account for somewhere around 2 to 3 percent of the direct household
energy use (11) and 4 to 27 percent of the household water use (19). Room
cleaning is responsible for a much smaller proportion of total water and energy
37
-------
TABLE 15. CHARACTERISTICS OF LIQUID RESIDUALS FROM KITCHEN
(Ib/cap/day)
Sink
Dishwasher
Garbage
Grinder*
BOD5
.018 -
.0011-
.024 -
(.021 -
.0233
.0282
.068
.10)
SS
.0051-
.00021-
.035 -
(.03 -
TN
.009 .001 - .0023
.0122 .0012
.096 .001 - .002
.14)
TP
.001
.001 - .0022
.000071- .0002
•*
It is reported that on the average .5 Ib/cap/day of garbage
results in .068 Ib BODs/cap/day and .096 Ib (dry) SS/cap/day;
assuming linear relations in the absence of data, the range
based on the range of garbage disposed (Table 16) would
result in approximately .021-.1 Ib BODs/cap/day and .03-.14
Ib SS/cap/day, respectively. (See K. Ligman, et al. (18))..
the low values are reported in the same study as the low flow
values (Bennett, E. R., et al. (17)).
the high values are reported in the same study as the high flow
values (Witt, M.D. (19)).
high value is reported in the study of low flow value (Bennett,
E. R., et al. (17)).
38
-------
TABLE 16. RANGES OF GENERATION RATES FOR EACH COMPONENT OF RESIDENTIAL SOLID RESIDUALS*
(kg/cap/day)
Combined Storage
and Disposal
Separated Stor-
age and Disposal
Organics Disposed
of by Grinder
L
H
L
H
L
H
Drganics
.08
.37
.09
.43
.02
.11
Paper
.09
.44
.08
.4
.08
.4
Glass
.06
.29
.06
.29
.06
.29
Metals
.06
.14
.06
.14
.06
.14
Plastics
.01
.09
.01
.09
.01
.09
Rubber
Leather
.005
.04
.005
.04
.005
.04
Textiles
.005
.05
.005
.05
. .005
.05
Miscel-
laneous
.002
.02
.002
..02
.002
.02
Total "f"
.31
1.44
.31
1.44
.24
1.13
u»
vo
* See Appendix D for derivation of figures (L = low; H = high)
t The totals were calculated under the assumption of independence of the components
leading to extremely high and low values.
-------
requirements. The principal appliances associated with this activity are
vacuum cleaners and electric floor washers and polishers, which together ac-
count for about one-tenth of one percent of direct household energy input.*
Water use for floor washing and other cleaning activities accounts for 1 to 5
percent of total household requirements (19).
Clothes Washing and Drying
Table 17 lists ranges of average energy and water consumption and residuals
generation by appliances used for clothes washing and drying, expressed in
units of consumption or residuals generation per capita/day.t
Clothes Washers—
In 1970 approximately 60 percent of the occupied dwelling units in the
U.S. had automatic clothes washers, and another 10 percent had non-automatic
washers (25). An automatic washing machine is considered to be a standard
appliance for most new single family homes, but these appliances are seldom
found in individual units of multi-family structures. However, often they are
provided in common areas. In dwellings that do not have washing machines most
of the water use and residuals generation associated with clothes washing is
"exported" to laundromats and commercial laundries. Only for very low income
families, and in isolated rural areas, is most clothes washing still done by
hand.
As shown in Table 17, the direct electrical energy use of the washing
machine is very small, but its use does contribute significantly to the house-
hold's water consumption and to the generation of BODs and suspended solids.
Washing machine effluent contains about 16 percent of the household's BODs
generation, 12 percent of the suspended solids and up to 50 percent of the
phosphorus where high phosphate detergents are employed.*
Clothes Dryers—
Dryers account for about two percent of the household energy use (11).
The percentage of homes with dryers ranges from 33 to 53 depending upon the
region of the country (26). Among households with dryers, about 67 percent
are electric units, the remainder are gas.
A typical dryer employs a 1/4-1/3 hp electric motor to operate the
tumbler and blower and uses a 4,000-5,000 watt electric heater or 10,000-
25,000 Btu/hr gas burner to generate the heat needed for evaporation. In
direct energy use the electric dryer is slightly more efficient than the gas
unit. For a 35 minute cycle the electric unit would utilize 9,900 Btu
(ignoring conversion losses at the power plant), the gas about 12,700. However,
* Meta estimate.
t Estimates on a per cycle or per use basis appear in Appendix A.
T Estimates based on averages from studies cited in Table 17.
40
-------
TABLE 17, INPUTS AND RESIDUAL OUTPUTS
WASHING AND CLEANING FUNCTION: CLOTHES WASHING AND DRYING
(Units/capita/day)
Energy Use
(Btu)
Electric Gas
Washing
Machine
-automatic 235-274 NA
-non-
automatic 203 NA
Water Use Wastewater
BOD,
(gal.)
Dryer
-gas (w.
pilot) 178-342 4,697-9,393"
-gas (w/o
pilot) 178-342 3,131-6,027
-elec-
tric 2,645-5,975 NA
x
(gal.)
4.2-18.1 4.2-18.1
x
Suspended Total
Solids Nitrogen
(lb) (lb)
.019-.033 .007-.024 0.0-.002
XXX
Total
Phosphorous
(lb)
.0001-.005
NA
NA
NA
NA
NA
NA -
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Iron 160-400
(electric)
NA
NA
NA
NA
NA
NA
NA
1. Does not include hot water energy. Electric energy is only Btu's used at home, not energy used to
generate electricity.
2. Evaporative losses ignored.
3. Pilot light consumes about 880 Btu/day.
4. Does not include electrical energy for ignition.
(continued)
-------
TABLE 17. (Continued)
5. Water use data for washing machines is based upon a small sample of actual users, while electric use
data was taken from annual averages reported in the sources listed below. As a result the ranges for
the two categories may not be completely consistent.
Notes: Where original data is based upon total household use a conversion factor of 3.5 people/
household is assumed, except where otherwise specified in source.
NA = not applicable
x = data unavailable
Sources: Energy: Edison Electric Institute (9).
Hittman Associates (11).
Federal Energy Administration (14).
Association of Home Appliance Manufacturers (20).
Citizen's Advisory Committee on Environmental Quality (21).
Water: Ligman, K., et al. (18).
Siegrist, R., et al. (22).
Bennett, E.R. and K. Linstedt (23).
Cohen, S. and H. Wallman (24).
-------
under existing pricing structures the electric dryer is from five to six times
as expensive to operate as a gas dryer (26).
Floor Cleaning
Floor cleaning includes sweeping, washing, waxing, and vacuuming. Water
use reported for this activity ranges from 0.45 to 2.05 gpcd (19). About one
gallon is employed to clean a full size room; thus water use for this activity
will increase somewhat with total floor area or number of rooms. Water used
for cleaning is usually taken from the sinks or tub and is thus included in
the values for kitchen and bathroom sinks and tub, and reported elsewhere in
the report. For the same reason values for wastewater and waterborne residuals
are not reported separately here.
Solid wastes are generated from the dirt and dust collected by sweeping
and vacuuming and from detergent packaging. These are included in the solid
waste storage and disposal activity for the kitchen function.
About 90 percent of households have vacuum cleaners. A much smaller per-
centage have floor washers and polishers (27). They are the principal energy
using appliances in this category. Average per capita and per event energy
requirements are listed in Table 18. Relative to major appliances these uses
are insignificant.*
BATHROOM
Bathroom activities include toilet flushing, bathing (tub and shower),
lavatory use (wash basin), and personal -upkeep. Lavatory use is defined as
water use and wastewater generation at the bathroom sink as opposed to personal
upkeep which encompasses electrical appliances such as hair dryers, water pics,
electric shavers, shaving cream heaters, and solid waste generation. For bath-
room activities energy use is primarily associated with heating water. How-
ever, only the amount of hot water required for bathing and lavatory use is
included in this section. Energy requirements have been treated above.
Water Use
Water use data are shown for various bathroom activities in Table 19.
Several of the factors influencing the quantities of water used for bathroom
activities are discussed below.
Toilet flushing—
The water use for toilet flushing shown in the table extends from
9.2 gpcd to 26.2 gpcd. Toilet flushing accounts for a major fraction of
the total household water use; estimates range from 22 percent (29) to 45
percent (19) of total daily residential water use.
One exception to the low level of energy use in this category is the central
vacuum system which is found in some houses. We do not have quantititative
data on the energy demand for this system, but the presence or absence of
such a system has been found to be significant as a predictor of household
electricity consumption (28).
43
-------
TABLE 18. ELECTRIC ENERGY USE FOR FLOOR CLEANING
Btu/capita/day ' Btu/event
Vacuum 90.3-122.9 2,218-2,580
Floor polisher 40.1-48.6 980-1,194
1 pirect use, does not include conversion at the generating plant.
2 Computed assuming one vacuuming or polishing "event" per week.
3 Assuming 3.5 persons/household.
Sources: Edison Electric Institute (9).
Boston Edison (10).
Citizen's Advisory Committee on Environmental
Quality (21).
44
-------
TABLE 19. WATER USE FOR BATHROOM (GPCD)
Function
Bath
Shower
Toilet
Lavatory
Total *
REFERENCE
123456
6.3 20.0 10.0 17.5 7.8 11.7
6.3 20.0 10.0 17.5 7.8 11.7
17.1 25.0 9.2 26.2 17.6 18.4
7 8
10.8 8.8
10.8 8.8
14.4 14.5
9
20.0
20.0
24.0
2.0
23.4 45.0 19.2 43.7 24.4 30.1
25.2 25.3
44.0
(Jl
References;
1. Cohen, S. and H. Wallman (24).
2. Bailey, J.R., et al. (29).
3. Witt, M.D. (19).
4. Haney, P.O. and C.L. Hamann (30).
5. Laak, R. (31).
6. Ligman, K. (32).
7. Wallman, H. (33) .
8. Bennett, E.R., et al. (17).
9. Reid, G.W. (34).
* Total includes either bath or shower, but not both.
-------
Conventional toilets have flushing volumes ranging from 3.0 gallons
to 5.5 gallons (19). Older toilets often have larger tank volumes and use
higher volumes per flush. The frequency of flushing reported in various studies
is shown in Table 20. Data on the frequency of toilet flushing by age group
show that the frequency for adults is 4.5 per capita/day, while for both teen-
agers (13-20 years) and children (1-12 years) the frequency is 2.4 (17). Com-
bining frequencies and flush volumes, minimum and maximum water use values of
6.9 gpcd and 24.8 gpcd, respectively, are obtained; the range agrees with
the literature values shown in Table 19.
Seasonal data show little difference between warm and cold weather periods.
In Wisconsin, summer use is 2 percent greater than winter use (19) whereas in
Connecticut, Rhode Island and California, data show winter use 4 percent greater
than summer use (24). These studies include families with children at school
during the winter period, but the effect of their absence during the school day
is minimal.
Regional data show average toilet flushing volumes of 16.8 gpcd in Con-
necticut and Rhode Island (35), 8.5 gpcd in Wisconsin (17), 14.7 gpcd in
Colorado (24), and 18.2 gpcd in California (36). The low value for Wisconsin
is the result of low frequency of flushing, as previously discussed. No
regional trend is apparent.
Bathing—
The range of water use for bathing, as shown in Table 21 is from 6.3 gpcd
to 20.0 gpcd. Bathing has been reported from 18 percent to 37 percent of the
total daily residential water use (35). Bathing involves either tub or shower
use and there is considerable variation in water use for each. The variability
of water use during a shower is high, due more to the duration per shower than
frequency of showering. Data indicate showers can take less (35), the same (17)
and more water (18) than tub bathing and exhibit a C.V. of 0.49. Studies have
shown a minimum volume of water for a shower is 2.5 gallons (17), and a maximum
of greater than 50 gallons (the shower being limited in duration to the hot
water tank capacity). Shower flow rates range from 5.0 gpm to 10.0 gpm (22).
Bathing water use ranges from 16.3 to 31.5 gallons per shower (35). Tub bathing
uses from 20 to 30 gallons per event. The average frequency of bathing reported
in various studies ranges from 2.2 to 3.3 times per week (Table 21).
Very little difference exists between the mean frequency of bathing accord-
ing to the data; however, disaggregation according to age group does show a
large difference. The most frequent bathers are the teenage group (from age 13-
20) with 5.3 baths per capita/week. Adults bathe at a frequency of 1.9 times/
week, and children (age 1-2) at 1.1 times/week (18). Multiplying these minimum
and maximum frequencies of bathing by the minimum and maximum volumes per
bathing event produces a range of 2.6 to 23.9 gpcd. This range is broader than
shown in Table 19.
Seasonal data show little variation for warm and cold weather. May to
November data show an average of 6.0 gpcd compared with December to April
averages of 7.0 gpcd (24). Seasonal differences do exist for hot water use
as discussed under energy requirements and water heating above. Regional
bathing data exhibit no definable trend in water use. In Connecticut and Rhode
46
-------
TABLE 20. FREQUENCY OF TOILET FLUSHING
Frequency
(flushes
per
capita per
day)
Monday
through
Sunday
Saturday
and
Sunday
Ligman* Ligman*
(Rural) (Urban)
3.6 -l- 1.5 3.6 + 0.9
(mean + std . dev . }
3.8 + 1.6 3.1 + 1.2
Bennett t
3c
• O
Siegristf
2-1 j. n PL
* Ligman, K,, et al. (18)
t Bennett, E.R., et al. (17),
t Siegrist, R., et al. (22).
TABLE 21. FREQUENCY OF BATHING
Frequency
(Number per capita
per week)
Iiigman*
(Rural)
3.1
Ligman*
(Urban)
2.8
Bennett t
2.2
Wittf
3.3
* Ligman, K., et al. (18).
t Bennett, E.R., et al. (17)
f Witt, M., et al. (35).
47
-------
Island the water use (gpcd) is 6.2 (24); in Wisconsin 9.3 (35); in Colorado
8.7 (17); and in California 6.6 (24).
Lavatory—
Little data exist on water use for the lavatory (bathroom sink). Studies
report total water use for all sinks in the household range from 9.9 gpcd (29)
to 18.0 gpcd (24). Bennett (17) reports water use at the sink (including the
lavatory) to be highly variable ranging from a "trace" to 48 gallons per
event (e.g., washing hair in the lavatory will greatly increase water use);
the mean is 1.7 gallons per "sink event" with a distribution of 35 percent
kitchen and 65 percent bathroom lavatory use. Based on this apportionment,
the lavatory is used daily 3.8 times by adults, 1.9 by teenagers (13-20 years
old) and 2.0 by children (1-12 years). This is approximately the same ratio
as toilet flushing. Using 1.7 gallons per use and the above frequencies, the
range of lavatory water use is 3.2 gpcd to 6.5 gpcd.
Wastewater Generation
The constituents of wastewater considered are BODs, suspended solids (SS),
total nitrogen and total phosphorus; bacterial concentrations are discussed
for potentially reusable bathing wastewater.
Toilet wastewater—
Toilet wastewater constitutes approximately 21 percent of the total resi-
dential BODs, 37 percent of the total suspended solids, 73 percent of the
total nitrogen and 33 percent of total phosphorus. It is estimated that toilet
wastewater contains daily fecal discharge of 100-200 gm (net weight) per capita,
urine discharge of 800-1,500 ml/capita and toilet paper of 4-20 gm/capita.
Associated with these are BODs values of 0.32 gm/gm feces, 0.009 gm/gm urine
and 0.20 gm/gm toilet paper (18). Table 22 shows a range of total BOD5 values,
0.015 to 0.083 Ib/capita/day and 0.004 to 0.015 Ib/event. Suspended solids
data show a range from 0.09 to 0.12 Ib/capita/day, or 0.017 to 0.022 Ib/event
(Table 23). The major nutrients, nitrogen and phosphorus, in toilet waste-
water are shown in Table 24. The range for total nitrogen is 0.003 to O".050
Ib/capita/day and for total phosphorus 0.003 to 0.008 Ib/capita/day. Study
data on nitrogen report 0.003 to 0.010 Ib/event. For total phosphorus the
value most often used is 0. 001 Ib/event. Ligman (18) reports that toilet
wastewater suspended solids are 82 percent volatile, total nitrogen is essen-
tially organic and ammonia type, approximately 50 percent of phosphorus is
ortho type, and approximately one-half the BOD5 is removable by filtration.
Bathing wastewater—
Bathing wastewater constributes approximately 8 percent of the BODg
and 4 percent of the suspended solids of the total residential waste load.*
The range of BOD5 for bathing wastewater shown in Table 26 is 0.007 to 0.032
Ib/capita/day; on an event basis, the range is 0.017 to 0.063 Ib. Comparable
figures for suspended solids shown in Table 27 range from 0.002 to 0.042 Ib/
capita/day. The range by event is 0.004 to 0.083 Ib/event.
* These wastewaters provide the best source of potential wastewater reuse
within the household. Table 25 shows the bacteriological characteristics
of the bathing wastewater. Analysis of isolates suggests that much of the
bacterial contamination of these wastewaters is probably from the natural
environment or the natural skin flora; therefore, their presence in the
bathing wastewater is not considered of great sanitary significance with
respect to potential reuse.
48
-------
TABLE 22. COMPARISON OF BOD5 DATA FOR TOILET FLUSHING WASTEWATER
BOD5
(pounds per
capita per
day)
BOD5
(pounds per
event)
Ligman*
°-025
Fecal(.017-.040)
„ . 0.023
Urine(.018-.037)
0.004
Paper(.003-.006)
m t , 0.052
T0tal(.038-.083)
0.014
Bennett t
0.010
0.005
-
0.015
0.010
Laakf
0.052
0.004
Witt *'*"
0.010
0.014
-
0.024
0.015
* Ligman, et al. (18).
t Bennett, et al. (17).
t Laak, R. (37).
** Witt, et al. (35).
49
-------
TABLE 23. COMPARISON OF SUSPENDED SOLIDS DATA
FOR TOILET FLUSHING WASTEWATER
Suspended
Solids
(pounds per
capita per
day)
Suspended
Solids
(pounds per
event)
Fecal
Urine
Paper
Total
Total
Ligman*
.048
(.040-. 062)
-
.020
(.010-. 040)
.068
(.050-. 102)
.018
Bennett
.048
-
.032
.080
.022
Wittf
.010
.014
-
.024
.017
* Ligman, et al. (18).
t Bennett, et al. (17).
f Witt, et al. (35).
50
-------
TABLE 24. COMPARISON OF TOTAL NITROGEN AND TOTAL PHOSPHORUS
DATA FOR TOILET FLUSHING WASTEWATER
Total
Nitrogen
(pounds per
capita per
day)
(per event)
Total
Phosphorus
(pounds per
capita per
day)
Feces
Urine
Paper
Total
Total
Feces
Urine
Paper
Total
(per event) 1 Total
Ligman*
.003
(.001-. 005)
.034
(.002-. 045)
-
.037
(.003-. 050)
.010
.001
(.001-. 004)
.002
(.002-. 004)
-
.003
(.003-. 008)
.001
Laakt
.032
.006
.001
.001
Bennett
.004
.008
-
.012
.003
.002
.001
-
.003
.001
Witt**
.003
.006
-
,009
.006
.001
.001
included
above
.002
.001
* Ligman, et al. (18).
t Laak, R. (37).
t Bennett, et al. (17)
** Witt, et al. (35).
51
-------
TABLE 25.* BACTERIOLOGICAL CHARACTERISTICS OF BATHING WASTEWATER
Organism
Fecal Streptococci
Fecal Coliforms
Total Coliforms
Range (per 100 ml)
1-70,000
1-2,500
70-8,200
Geometric Mean (per 100 mfc)
44
220
1,100
Siegrist, et al. (22).
TABLE 26. COMPARISON OF BOD DATA FOR BATHING WASTEWATER
BOD5
(pounds per capita per day)
BOD5
(pounds per event)
Ligman*
0.020
(.011-. 032)
0.039
(.022-. 063)
Bennettf
0.007
0.023
Wittf
0.007
0.017
* Ligman, et al. (18).
t Bennett, et al. (17).
t Witt, et al. (35).
52
-------
The range of BODs and suspended solids values for bathing is not reduced
by considering per event basis. This indicates the wastewater residuals from
an individual bathing event are highly variable as contrasted to less variable
toilet flushing wastewater when considered on a per event basis.
Lavatory wastewater—
Minimal data exists on segregated lavatory characteristics; a summary of
available data is shown in Table 28. The nutrients are zero but the BODs an^L
suspended solids contribution is greater than from bathing. Some typical pro-
ducts which may be introduced into the lavatory wastewater are shown in Table 29.
Data for lavatory wastewater residuals indicate contributions of approximately
8 percent of the BODs and 6 percent of suspended solids to the total residential
liquid residual.
Energy
Small electrical appliances used for personal upkeep are shown in Table 30;
estimating the total time of use per year, the annual energy use of these
appliances is calculated as 27.3 kwh.
The major energy use in the bathroom is associated with water heating;
it is estimated that approximately 40 percent of household hot water use occurs
in the bathroom (24). Seasonal variation exists with winter use of hot water
for bathing being 30 percent greater than summer use; hot water use in summer
is approximately 55 percent of total bathing use. Based upon an aggregate of
bathing and lavatory use, a range of 9.5 to 26.5 gpcd is calculated. The
amount of hot water associated with this range is 5.2 to 14.6 gpcd and 6.8 to
19.0 gpcd summer and winter use, respectively.
LIVING AND ENTERTAINMENT
Television is the major energy user in this category (but still a small
percentage of total household energy use). A color television uses more
energy than a black and white and a tube television uses more than a solid
state as is shown in Table 31. The "instant-on" feature of many televisions
can double the amount of electricity used. This feature is expected to dis-
appear from new sets.
Other items which contribute to energy consumption under this function
are stereos, radios, and electric hobbies and games. A stereo uses the same
amount of electrcity per hour as does a black and white tube television.
Radios, electric hobbies, and games use much less. Slide or film projectors
are another, minor, energy-user.
Entertaining guests is a major activity for some families. Depending
upon social tastes and income, entertaining can influence other functions,
such as the kitchen and washing and cleaning, in terms of the amount of energy,
foods and other materials consumed and the quantities of residuals produced
from cans and bottles, food waste and packaging, wastewater from dishwashing
53
-------
TABLE 27. COMPARISON OF SUSPENDED SOLIDS DATA FOR BATHING WASTEWATER
Suspended Solids
(pounds per capita
per day)
Suspended Solids
(pounds per event)
Ligman*
0.012
(.002-. 042)
0.027
(.004-. 083)
Bennettt
0.002
0.006
Wittt
0.005
0.013
Ligman, et al. (18).
Bennett, et al. (17).
Witt, et al. (35).
TABLE 28. LAVATORY WASTEWATER CHARACTERIZATION
Residual
(pounds per capita
per day)
BOD5
0.011
Suspended
Solids
0.009
Total
Nitrogen
0.0
Total
Phosphorus
0.0
Bennett, et al. (17).
54
-------
TABLE 29. POTENTIAL CONTRIBUTION OF LAVATORY INPUT MATERIALS
Hair
Care
Hand
Soap
Tooth
Care
Fitch Shampoo
Wella by Balsam
Breck Setting
Lotion
Dial
Unknown
Ultra Brite
Tooth Powder
Ratio*
b
b
b
a
a
a
a
COD
1.024
4,720
0.054
2.355
2.375
3.171
2.602
BOD
.084
.026
XX t
1.809
1.840
0.200
0.082
Total PO.-P
4
0.0
0.0
0.0
0.0
0.0
0.098
0.0001
* a = ratio mg of pollutant product to mg of product;
b - gro of pollutional product to ml of product.
t xx = material was toxic to BOD testing organism.
Source: Bennett, et al. (17).
55
-------
TABLE 30. ENERGY USE FOR PERSONAL UPKEEP*
Appliances
Hair Dryer
Heat Lamp
Shaver
Total
Wattage
600
250
14
Use Time/Year (hrs)t
39
13
52
Killowatt-hours/year
23.4
3.2
0.7
27.3
* Association of Home Appliance Manufacturers, Edison Electrical
Institute (9).
t Meta Systems average estimate based on much diverting figures in
literature.
56
-------
TABLE 31. ENERGY CONSUMPTION OF TELEVISION
Energy Consumption*
Average Wattage kwh/year 10 Btu/cap/dayt
Black and White 50 - 160 100 - 330 .27 - .88
Color 175 - 300 350 - 525 .93-1.4
* ocicurcition i
1970 1990
99 85
51 98
* The values of the range are comprised of average values given for tube (upper bound)
and solid state (lower bound) in reports of the Edison Electric Institute (9).
t "Project Independence" (14).
in
-------
and so forth. Large groups of people can contribute greatly to the cooling
load as can extensive use of the stove and oven for food preparation.
Finally/ personal hobbies can range from the passive non-consuming sort
(stamp collecting) to a moderately energy-using sort (sewing) to larger energy
and material users such as wood-working and carpentry (assuming power tools).
Although there are no data on these activities it is reasonable to assume
that on the average resource utilization is insignificant and residuals gener-
ation is minimal
OUTDOORS
The two most important activities within the outdoors function are garden-
ing and recreation. Of these, gardening uses more resources, particularly
water, and generates a greater volume of residuals in the form of yard clip-
pings, grass and leaves. In the warmer part of the country recreation might
include a swimming pool, but its water use is a rather small component of
total outdoor water consumption.* The greatest users of energy outdoors are
power tools for gardening, swimming pool filter pumps and heaters, and lighting
for entertainment and recreation. However, the requirements are negligible
and quantitative estimates are not made under the outdoor function. Also, the
wastewater generated directly by outdoor activities is insignificant, except
in the cases of consistently over-watering the lawn or garden.
One phenomenon (as opposed to activity) which is included under the out-
doors function is that of stormwater runoff. Although not directly the
consequence of any particular activity, it is often as great -a source of
wastewater as all the other water use activities.t Moreover, because of the
peaking character of storm runoff the environmental effects can be far more
serious. Below, efforts to estimate runoff from residences are discussed fol-
lowing a review of outdoor water use and solid residuals studies.
Water Use
There are tremendous variations in the estimates of outdoor water use
reported in the literature. Lawn watering and the irrigation of plants and
shrubs, which account for almost all that is used, differ across regions, vary
with the season, and demonstrate a demand behavior which is both price and
income elastic (39). In addition, the amount needed to care for lawns and
shrubs depends on the area of yard available for gardening. Linaweaver (40)
Lumped in a category which includes car washing and cleaning of driveway,
sidewalks and streets; water for swimming pool use is less than 10 per-
cent of outdoor water consumption. California Department of Water Resources
(38).
For example, a residence on a one-quarter acre lot in a region with an
average annual rainfall of 40 inches of which 40 percent runs off would
generate an average daily flow of almost 300 gallons. This is equivalent
to the wastewater flow of a family of four persons.
58
-------
reports that in the West residential units use twice as much water as
comparable eastern units and that for the nation as a whole the ratio of sum-
mer use to average annual use is approximately 2.5. Discussing the results of
a study on 39 communities, Howe andLinaweaver estimated that for a subset of
these communities in the West the outdoor water use in the areas with water
meters was 186 gal/day per dwelling unit and in the unmetered areas the figure
was 420 gal/day per dwelling unit while indoor water use differed by less
than 5 percent. Augmenting the data with metered communities from the East
they estimated that the price elasticity was -1.16 and the income elasticity
was 1.07 (39). These elasticities showed that outdoor use of water is far
more sensitive to price and income than is indoor use.
In reviewing several studies of residential water use Milne concludes
that a reasonable estimate of outdoor use is 70' gpcd (41). A recent review
of water demand in California, employing data from 1972, reports that total
residential use was approximately 151 gpcd of which 66 gal (or 44%) was
consumed outdoors primarily for landscape irrigation (38). Andrews (42) found
in a study of three New Hampshire towns that in two of the towns fewer than
10 percent of the residences watered the lawns at all. However, in the
demand study of Howe and Linaweaver (39), the authors report that during the
summer the mean daily outdoor water use in the unmetered eastern communities
of their sample was over 1,000 gallons.
Clearly the variation is significant. Nonetheless, except for the case
of the New Hampshire towns, most residences use a considerable amount of water
outdoors during those seasons when the weather is favorable. In some regions
that implies a substantial demand throughout the year,
Solid Residuals
The weight of solid waste generated by a household in landscaping and
gardening varies widely. As with outdoor water use, seasonal, regional, and
income effects and type of residence are important. However, there are few
data available and most estimates are not based on direct measurements, but
on educated guesses or very small samples. For example, in three studies con-
taining figures on the composition of residential solid waste for Santa Clara
County, California, the estimate of the percentage by weight of yard wastes
in one study was 23.8 percent, in the second study it was 9 percent and in
the third study it was 34.5 percent (43, 44, 45). Such apparent discrepan-
cies are not unusual and may depend on nothing more than the time of year when
the data were collected. In a study of municipal solid waste in Springfield,
Massachusetts, the average percentage of garden waste varied considerably over
the city for the four seasons. In the winter it was 0.0 percent, in the
spring 10.0 percent, in the summer 21.0 percent, and in the fall 34.5 percent
(46). Converting these figures to pounds per household per week (Ib/HH/wk)
increases the variation.
Ib/HH/wk
Winter 0.0
Spring 5.4
Summer 9.7
Fall 25.1
59
-------
Estimates of these generation rates varied considerably with the housing
characteristics of the city; clear correlations, however, could not be
established. With the kind of range exhibited by the estimates it is imprac-
tical to put forward a single figure to be used in all circumstances requiring
the calculation of solid waste load. Nonetheless they do show the importance
of yard wastes as a component of residential solid waste and demonstrate that
at certain times of the year leaves and lawn clippings may be the major items
in refuse.
Stormwater Runoff
Studies have shown that significant relationships exist among certain
gross characteristics of residential areas and the quantity and quality of
stormwater runoff. For example, the data from Sartor and Boyd (47) and the
subsequent re-analysis by Sutherland and McCuen (48) distinguish between sin-
gle and multi-family residential areas for the purpose of predicting accumu-
lation rates of dust and dirt per curb mile. Likewise relationships between
population density and street length per acre (49) and percent impervious-
ness have been developed (48). These show that as density increases street
length/acre and percent imperviousness increase and hence the total pollutant
load and runoff/acre increase. Young (50) has employed a simple model to
evaluate the impact of total population and population density on runoff and
water quality. However, these aggregate relationships obscure issues of
fundamental importance when the individual residence or subdivision is con-
sidered in detail. The impacts on runoff at this level are not well known,
although recently some work has been proposed in this area (51).
MAINTENANCE
Under the function of maintenance are such activities as upkeep and repair
of the interior and exterior of the residence and care and cleaning of an
automobile. Maintenance of a residence requires small amounts of energy and
water and generates little in the way of residuals. Although no data are
available it is safe to assume that amounts of resource uses and residuals
created are negligible. However, an automobile, depending on the habits of
its owner, may be a different matter.
Automobile Maintenance
Washing a car can require between 150 and 300 gallons of water.* If the
car is washed on an impermeable surface or in the street, a substantial portion
of the water may run off into the sewer system carrying with it the detergent,
grit, salt, paint and other forms of debris which are washed from the car and
scoured from the driveway and street. If the car is washed on a permeable
surface, most of the water probably infiltrates and there is little runoff.
* Assume flow to be between 5 gal/min and 10 gal/min and time to wash car
1/2 hour.
60
-------
However, this is another case in which there are no data. The best esti-
mates available which may be applicable are from a study which includes some
data on self-service auto washers. The pollutants which were measured were
total solids, total volatile solids, suspended solids, volatile suspended
solids, BOD5, and oil and grease (52). The results appear in Table 32. The
concentrations of total solids, total volatile solids, suspended solids, and
grease are very high. However, the study reports that the average volume of
water used per car is only 20 gallons which is much lower than our estimates
of the water needed when washing a car at home. In the latter case it is
reasonable to assume that the concentration of pollutants would be much lower.
One other auto maintenance activity generates an important residual. The
backyard oil change means that used lubricating oil must be poured in the
sewer, flushed down the toilet, spread on the ground or taken to a collection
facility. Recent estimates of the annual automotive consumption of motor oil
place the figure at 1.1 billion gallons. A little less than half is burned
or somehow lost in the process of lubrication leaving 600 million gallons to
be reused or disposed of in some way or other (53). For a long time most of
the oil was drained and replaced at service stations where the used oil was
stored and eventually hauled off to be treated or rerefined for use as a fuel
or lubricant or in the manufacture of asphalt. However, today almost half of
the automotive lubricating oil is sold by discount stores and other outlets
(54). People are now changing the oil in their cars and the used oil is
being dumped along with the lead, copper, barium, zinc, phosphorus, tin, or
chromium it may contain. This is another case where there are no data on
the magnitude or distribution of the residuals,, although it is probably
reasonable to assume that in certain areas the problem may be important.
TABLE 32. TYPICIAL POLLUTANT CONCENTRATIONS IN WASTEWATER FROM
SELF-SERVICE AUTO WASHERS OVER A 10 MONTH PERIOD
(all units mg/1)
Minimum Maximum Average
Total Solids 729 3,334 2,006
Total Volatile Solids 207 871 456
Suspended Solids 95 840 386
Volatile Suspended Solids 25 116 72
BOD 5 15 166 57
Grease and Oil 38 200 86
61
-------
SUMMARY
Organizing the use of resources and the generation of residuals by func-
tion allows us to: (a) identify the important functions for each resource and
residual; (b) observe the great variance of the rates even within functions;
and (c) illustrate, where data allowed, links between certain pairs of func-
tions and levels of resources used or residuals generated.
In the case of resources, the greatest energy user, given current levels
of insulation (e.g., FHA 1973) and central heating and air conditioning sys-
tems, is space heating/cooling. In those parts of the country with at least
5,000 degree days, heating can account for more than 75 percent of the energy
requirement. The second most important use of energy is water heating, in a
household with four persons the requirement can range between 20 x 10° Btu/yr
and 45 x 106 Btu/yr. Depending on space heating, water heating can use from
10 percent to over 50 percent of the household's energy. All other functions
tend to be marginal, in that any one of them usually accounts for less than five
percent of the total. Nonetheless, such items as frost free refrigerators and
freezers and kitchen ranges with standby pilots can use more energy than com-
parable models without these features.
Water is used in the greatest quantities in the bathroom. In most homes
the toilet accounts for somewhere between 30 percent and 50 percent of the
water used. Bathing and showering are also important. Other significant water
using activities are clothes and dish washing. In addition, lawn watering can
be very substantial, particularly in the spring and summer. One study cited
above reported, for a group of eastern communities, a rate of over 1,000
gallons/day for outdoor residential use during the warm months.
The gaseous residuals and the hydraulic load of the liquid residuals are,
to a large extent, proportional to the energy used (for space heating and water
heating) and the water used respectively. Clearly the composition of the gase-
ous effluents depends on the type of fuel burned and the efficiency of the fur-
nace but the primary sources of the gases are space heating and water heating.
Minor sources are such items as gas ranges and dryers. Little if any water is
consumed in household activities; virtually all becomes part of the liquid
waste stream. The other constituents of the liquid residuals, particularly
BOD5 and SS, have their source in the bathroom and the kitchen (an important
source if there is a garbage grinder). Outdoors, stormwater runoff may be a
very important source of liquid residuals.
Placing solid residuals under the kitchen function obscures the wide range
of actual sources. However, a review of the composition estimates presented
above and in Appendix A suggests that all functions might make some ccatribu-
tion. Important functions are kitchen (organics, glass, metal and some paper
and plastics), living and entertainment (newspapers) and outdoors (leaves,
grass, etc.)
62
-------
The great variance in the rates of resource use and residuals generation is
remarkable. As remarkable is the fact that so little of the variance is
explained in the studies which report use and generation rates. In order to
provide some perspective on the great range of estimates, -we present in Section
7 baselines in which we specify the characteristics of the structures which
determine the amounts of resources used and residuals generated.
Two relationships can be established linking resources or residuals across
functions. Neither is very surprising. First, the energy required for water
heating is a function of the volume of water used for bathing, dishwashing and
clothes washing. Second, the components of the liquid residuals and the solids
residuals depend on whether or not there is a garbage grinder in the residence.
Limited data and the fact that most empirical resource use studies concentrate
on only one item (e.g., energy) make the identification of other links diffi-
cult.
63
-------
SECTION 6
CONSERVATION MEASURES AND THEIR DIRECT COSTS
INTRODUCTION
Conservation can be achieved through technological or behavioral changes.
It can occur at the point of use, where the savings may be dramatic, and at
the point of generation, where residuals may be recaptured, recovered and
reused rather than discarded. As has been pointed out in Section 5, for many
activities resource use and residuals generation are highly dependent upon
such factors as region of the country, socio-economic characteristics, climate
and season. However, in spite of wide variations in use and generation rates,
structural improvements, in particular, and other conservation measures and
practices can result in impressive reduction in waste of resources and the
generation of residuals.
Often the choice of construction materials, the soundness of a structure,
or the design of appliances can significantly alter the amount of energy,
water, or other resources consumed by a particular household function.
Similarly, the capture of residuals for reuse often requires physical modifi-
cations in residences. Plumbing, for instance, must be specifically designed
to transport, store, and, in some cases, treat reusable wastewaters; storage
space or collection sites encourage solid waste separation; waste heat can be
recaptured with special devices.
In a complementary fashion, the preferences of residents — e.g, the
temperature at which thermostats are set, the length of time and manner in
which appliances are utilized, and the volume of hot water used in bathing —
can affect the use of resources. Although the importance of individual beha-
vior is acknowledged, in this section most of the emphasis will be placed on
structural modifications and improvements in the efficiency of devices.*
SPACE HEATING AND COOLING
Structurally, the most effective measure for reducing energy use in
heating and cooling in residences is insulation. In Table 8 of Section 5
we have shown that for a single family house the addition of 3 5/8" of insu-
lation material in walls, 2" around the floor, and 4" in the ceiling can
T}ie one exception to this is the case of solid residuals recovery. Indi-
vidual behavior is essential for conservation.
64
-------
reduce heat loss by more than 50 percent compared with the uninsulated house.
The effect on cooling load is comparable (see Table 9 of Section 5). Perhaps
the most obvious choice after insulation is the addition of storm windows.
Their effectiveness in reducing heat loss is 10 to 20 percent. Tables 33
(Heating) and 34 (Cooling) contain the incremental heat loss reduction for the
addition of insulation from 1" to 24" in the ceiling and from 1" to 5 5/8"
in the walls and heat loss reduction resulting from the installation of storm
windows. Cost estimates appear in Table 35.
The high levels of insulation in the ceiling require a well ventilated
space between ceiling and roof beams. In the walls, more than 3 5/8" of insu-
lation can be accommodated only by using 6" studs or by attaching insulation
board to the outer surface of the stud wall. For our cost calculations we
assume that 6" studs are used.
In addition to insulation and storm windows, energy can be saved by
modifying the furnace, placement of windows, trees and shrubs, the color of
the building, and the use of drapes, shades, and awnings. The modification of
conventional furnaces is a measure which is promising although somewhat contro-
versial. Such modifications usually rely on some type of device which uses
the flue gas to preheat the water or air before it enters the boiler or heat-
ing chamber of the furnace. Advocates claim that fuel use can be reduced
by about 20 percent (55). Cost estimates for such devices vary between $200
and $400.
The placement of windows is especially important in summer cooling since
the major source of heat gain is solar radiation rather than the indoor-
outdoor temperature difference. It can be minimized by having the major por-
tion of glass area facing north and south. The cooling load through an
unshaded east or west window is three times as much as through a north window
and twice as much as through a window facing south. For example, the cooling
load of a 1,500 sq ft house with all its windows (220 sq ft) on the east and
west sides of the building is approximately 30 percent greater than the same
house with its windows facing north and south. Although the placement of
windows to reduce cooling load might increase heat loss in the winter, it is
less important.
Another factor to consider in window placement is the direction of pre-
vailing winds. A window facing a 30 mph wind will lose at least ten percent
more heat than one facing a 15 mph wind. The lay of the land can also impact
energy conservation. For instance, mounding can act as a windbreak and
decrease heat loss through windows and walls. However, the better the struc-
ture, the lesser will be the effect of high winds and windbreaks.
Landscaping is sometimes a very effective method of energy conservation,
serving as a windbreak and a shading device. Deciduous trees will service to
shade walls and windows in summer while allowing solar radiation to penetrate
in winter. The heat gain of an east or west facing wall or window, if shaded,
is reduced to that of a north-facing wall. In the case of the window, the
shading reduces heat gain by about 67 percent. Also, the branches and trunks
of trees will act as partial windbreaks in winter, particularly if trees are
planted in clusters.
65
-------
TABLE 33. INCREMENTAL HEAT LOSS SEDUCTION*
(BTU/SQ FT FLOOR SPACE/DEGREE DAY)
Roof
Insulation:
1st inch
2nd inch
3rd inch
4th inch
5th inch
6th inch
9th inch
12th inch
15th inch
18th inch
21st inch
24th inch
Wall
Insulation :
1st inch
1 1/2 inches
2nd inch
3rd inch
3 5/8 inches
4th inch
5th inch
5 5/8 inches
Storm Windows
Single-Family
1- story
2.5
1.9
.6
.6
.3
.3
.39
.19
.12
.08
.06
.06
1.9
.5
.2
.3
.2
.08
.15
.07
2.1
Single-Fami ly
2-story
1.2
1.0
.3
.3
.1
.1
.18
.09
.06
.04
.03
.03
2.8
.8
.2
.5
.2
.13
.23
.10
2.1
Townhouse
Row
1.2
.9
.3
.3
.1
.1
.19
.09
.06
.04
.03
.03
1.4
.4
.1
.4
.1
.06
.12
.05
1.7
Low Rise
3-story
.7
.6
.2
.2
.1
.1
.11
.06
.04
.02
.02
.02
1.2
.3
.1
.2
.1
.04
.07
.03
1.7
To find total annual fuel use reduction due to any one measure, multi-
ply the reduction in the above table by number of heating degree days
(Appendix B, Table B-2) for the area and by the total floor area for the
structure. (All reductions are incremental and therefore additive, i.e.,
the savings for the 3rd and 4th inches of insulation on a single-family
one-story are equal to 0.6 + 0.6 = 1.2 Btu/sq ft Floor Space/Degree Day.)
This gives the total annual reduction for the structure assuming a 65°
indoor temperature and 100 percent fuel use efficiency. To adjust for
other temperatures use Table B-3 (Appendix B),
66
-------
TABLE 34. COOLING LOAD REDUCTIONS
t.
(90°F OUTDOOR;* BTUH/SQ FT FLOOR SPACE )
ROOf
Insulation :
1st inch
2nd inch
3rd inch
4th inch
5th inch
6th inch
9th inch
12th inch
15th inch
18th inch
21st inch
24th inch
Wall
Insulation :
1st inch
1 1/2 inches
2nd inch
3rd inch
3 5/8 inches
4th inch
5th inch
5 5/8 inches
Storm Windows
Single-Family
1-story
4.8
3.7
1.0
1.0
.5
.5
.568
.284
.183
.121
.081
.081
2.4
.7
.2
.3
.2
.074
.15
.074
2.9
Single-Family
2-story
2.2
1.8
.5
.5
.2
.2
.270
.135
.087
.058
.038
.038
3.6
1.0
.2
.5
.2
.13
.223
.112
2.9
Townhouse
Row
2.3
1.8
.05
.05
.2
.2
.274
.137
.088
.059
.039
.039
1.9
.5
.1
.3
.1
.074
.112
.056
2.0
Low Rise
3- story
1.4
1.2
.3
.3
.2
.2
.163
.082
.052
.035
.023
.023
1.2
.3
.1
.2
.1
.037
.074
.037
2.0
To convert for 85° outdoor: multiply above roof values by .86, above
wall values by .73, and above window values by .87.
To find total annual reduction for any measure, multiply above coef-
ficient by total floor area of the structure and by the number of cooling
hours per year found in Table B-2 (Appendix B).
67
-------
TABLE 35. COSTS OF INSULATION AND STORM WINDOWS
(IN NEW HOUSING)
Ceiling & Wall
Insulation
1"
1 1/2"
2"
3"
4"
5"
6"
Floor Perimeter
Insulation
1"
1 1/2"
2"
Storm
Windows
-
Cost* Total Cost
($/ sq ft) Ceilingt
.25
.27
.29
.34
.38
.43
.48
Incremental Cost
($/linear ft.)
.45
.55
.66
Incremental Cost
($/sq ft)
2.00
$435
470
505
592
661
748
835
Total Cost
Floors
$72
88
106
Total Cost
Windows tt
$440
Total Cost
Wallst
$265
286
307
360
403
456
509
Footnotes on following page
68
-------
Footnotes for Ta£le 35
* For levels of wall insulation greater than 3 5/8% studs must be in-
creased from 4" to 6H. The above figures do not include these stud
costs. However in our calculations in Section 7 we use studs; $0.43
per linear foot for 2x4's and $0,56 per linear foot for 2x6's. This
represents a total difference of $125,00, or $0.12 per square foot of
wall area for our 1-story single family home, assuming the studs are
spaced 16" on center. For levels of roof insulation greater than 6"
we use $0.32 per square foot for 3" increments and $0.48 per square
foot for 6" increments.
t assume roof area of 1740 sq ft.
t assume wall area minus windows of 1060 sq ft.
** assume perimeter of 160 ft.
*** assume window area of 220 sq ft.
68 (a)
-------
The color of both roof and walls can reduce heat gain due to solar
radiation. A light-colored wall will absorb much less heat than a dark wall
and can reduce the total heat gain for an unshaded house by about four percent.
Since roofs usually accumulate dirt, a light-colored roof may not remain so;
nonetheless, it can reduce total heat gain by 10-15 percent.
Awnings will have the same effect as shade trees in reducing solar
radiation through windows. Indoor shades such as Venetian blinds and curtains
are also effective. They can reduce heat gain by 30-40 percent on east, west
or south walls, and 25 percent on north-facing walls. The difference is
greater on the east and west walls than on the others, since the initial
radiation is greater. Table 36 lists several measures which reduce cooling
load by reducing solar radiation through windows. Cost estimates are not made
because they can vary too widely.
Solar Heating and Cooling
Solar heating and cooling systems are becoming economically attractive.
Although the costs and design features have not yet stabilized on the consumer
market, there are two widely accepted systems for which general concurrence
exists on likely future costs.
In one system, water (treated with a chemical anti-freeze) circulates
through collectors which are composed of black-surface metal plates enclosed
by glass. Solar radiation absorbed by the plates is transferred as heat to
the water which is then stored in a large well insulated tank (called the
"store"), usually located in the basement of the residence. From the store,
the heated water is piped throughout the house and a variety of heat-exchange
systems can be used to warm the room air. Alternately heat from the store
may be transferred to a separate water circulation system for distribution
throughout the structure. Thermostats control the rate at which the water
circulates through the collectors and through the heating system. The other
system uses air rather than water. In principal it is the same except that
air is heated in the collectors, blown into a store of stones which trap the
heat, from which heated air is carried into the living space.
In either system, a conventional heating unit is usually required for
those times when the heat store is depleted. Also, most systems require
some auxiliary energy source to operate the pumps, blowers and other mechani-
cal features. "Passive" systems, which do not incorporate such features,
have been used but they require the occupants of a residence using such a
system to accommodate themselves to the limits of the system (56).
Test runs of a solar cooling system in Colorado are yielding encouraging
results (57). Similar to the water-based heating system, the cooling system
uses a heat exchanger to transfer heat from the collector fluid to the
storage fluid. The distribution system uses forced air. Hot water from the
storage tank is piped to the cooling unit where the water provides the energy
to operate a standard three-ton lithium bromide absorption air conditioner
adapated for hot water.
69
-------
TABLE 36. REDUCTION DUE TO SWITCHING WINDOW EXPOSURE AND INSTALLING
SHADING DEVICES
(BTUH/SQ FT WINDOW)1'2'3
For each square foot of window switched from east or west, multiply by:
Single Window Storm Window
To:
North 75 64
NE/NW 32 29
SE/SW 14 12
South 53 46
For each square foot of unshaded window affected by the following shading
devices multiply by:
Drapes or Venetian Blinds
2.
3.
4.
North
NE/NW
E/W
SE/SW
South
North
NE/NW
E/W
SE/SW
South
North
NE/NW
E/W
SE/SW
South
86
64
43
53
75
Roller
82
53
26
38
68
79
78
77
78
79
73
53
34
43
62
Shades Half -Drawn
69
39
18
29
53
Awnings
72
70
70
70
72
1. After the values in the table are multiplied by the square feet of
window affected, to find the annual reduction in cooling load, mul-
tiply by cooling hours/year for your city.
2. Measure 1 is additive with either 2, 3, or 4. But 2, 3, and 4 are
not additive with one another.
3. These values are valid for average outdoor heating season temper-
atures between 85° and 100°.
-------
Debate continues about the amount of heating or cooling that a solar
system can provide for a residence. Massdesign estimates that the systems
they considered can achieve from 43 percent to 88 percent savings in the
amount of auxiliary fuel required for space heating and water heating (56).
Arthur D. Little, Inc., however, found in a study for ASHRAE that only 30-50
percent of the space heating could be economically provided by a solar system
on the basis of their cost calculations (58).
The Colorado study found from actual tests in prototype homes that the
solar systems could carry 40 percent of the normal cooling load (between
August 1, 1974 and January 31, 1975), 86 percent of the space heating load and
68 percent of the domestic water heating load. However, heat losses from the
store and circulation system accounted for almost half of the cooling load
during August. Modification of the system subsequently raised the percent of
solar cooling provided to 55.8 percent (57).
Costs of Solar. Systems
Studies by Arthur D. Little, Massdesign and Colorado State University have
assumed that collectors cost $6-7/sq ft, installed. Massdesign and the Colo-
rado study group predict that the cost of collectors should drop to $4/sq ft
as designs are simplified, the quantity of material used is reduced and the
manufacturing labor is decreased. Massdesign cost estimates for several of
their synthetic cost simulations appear in Table 37. The Colorado study
found that the typical system can provide 70 million Btu/year for a cost of
$6-7/million Btu (57).
According to the same study a 3-ton solar cooling unit costs about $2,000
to provide 250,000 Btu seven hours a day at peak capacity using the same
solar collector and storage (57). In a report by the National Bureau of
Standards, the cost estimate for a similar unit with necessary auxiliary equip-
ment was closer to $3,000, (59).
WATER HEATING
Potential savings in energy use by water heaters can be obtained in
three areas: design, installation and use. Design improvements would increase
the energy efficiency of water heaters by reducing the heat loss with added
insulation and increasing the efficiency of gas burners and associated heat
transfer systems. Burner efficiency can be improved by attaining more com-
plete combustion and through the use of multiple-stage burners which allow
the unit to match heat loads with burner use more effectively. Improved heat
transfer will reduce the temperature of the exhaust gases, reducing heat
lost "up the stack." The industry appears to be moving toward increasing
efficiency. This can be seen by comparing current ASHRAE standards with those
which will be in effect in 1977 (13). For electric heaters, the current
standard allows a maximum stand-by heat loss of six watts/sq ft of heater
surface (20.5 Btu/sq ft) and will be reduced to four watts/sq ft (13.6 Btu/
sq ft). For gas and oil water heaters the required recovery efficiency (fuel
to hot water) is 70 percent and will be increased to 75 percent. Maximum
stand-by heat loss in percent of energy use is 4.3 + 67/V where V is the
71
-------
TABLE 37. SOME EXAMPLES OF COST ESTIMATES FOR SOLAR HEATING SYSTEMS*
Net Heated Net Collector System Energy Sup- Cost/Effect.
Hornet Area (sq ft) Area (sg ft) Cost ($) plied (106 Btu) j ($/106 Btu)
Solar Cape
-Water 1,844 715
Solar Cape
-Water (Low 1,844 400
Cost)
Solar Saltbox
-Water 1,844 1,215
Solar Saltbox
-Mr 1,844 965
Solar
Townhouse 1,650 715
6,900 71.3 (69)
2,800 43.2 (42)
8,750 85.2 (88)
5,900 67.5 (84)
5,500 55.7 (93)
9.
6.
10.
8.
9.
7
5
3
7
9
.* See Reference (56)
t The names in the list refer to the style or type of structure (e.g. cape,
saltbox) and the type of solar system (water or air).
T The numbers in parentheses are the percentage of the total Btu require-
ment.
72
-------
heater volume, in gallons. This will be reduced to 2.3 + 67/V in 1977.
Estimated effects of these improved design standards are indicated in
Table 38 for electric and gas heaters delivering 80 gal/day at 1208F with an
inlet water temperature of 60°F and a room temperature of 70°F. Under the
assumed conditions the improved standards will reduce wasted heat by 20 to
30 percent and overall hot water energy demand by five to six percent. Yet a
flow-through heater can be more efficient (close to 80 percent) and can
eliminate the need for a stand-by pilot (60).
In addition to the performance of a water heater, its size and location
are important. Over-capacity or under-capacity can increase substantially
stand-by heat loss. The location of the heater should be selected to avoid
a long run of pipe line. Heat loss may be further limited by insulation of
the circulating line.
For any given hot water heater installation, energy use can be reduced
by lowering the hot water temperature. In the past, heaters have often been
set at 140-150°F. A value of 120°F is now generally recommended for energy
conservation. For the electric heater in Table 38 the 120°F temperature
results in 28 percent lower conduction loss. This results in a lower total
water heating energy use of above five percent. One problem to consider in
setting the water temperature lower is the effect on hot water demand. If
use habits do not change, then certain activities such as bathing will demand
more hot water in order to obtain the same temperature.
Water conservation practices, discussed elsewhere for the individual
activities, will reduce hot water demands and energy use. Further conser-
vation of energy may be affected by controlling the amount of time the heater
is functioning. For example, if bathing, dishwashing and laundry activities
could take place in either the morning or at night (preferably at night
to avoid peak use), the heater could be turned on several hours before this
time and then disconnected after use.
The cost of a more efficient storage water heater can vary. Currently
a 40 gallon gas heater costs from $130 to $180,depending on the quality of
insulation and burner (the cost of installation is additional). Prices
increase about $10 for each 10 gallon increase in storage capacity. Electric
storage heaters are $30 to $40 less than comparable gas units. A reasonable
estimate of the cost differential for a heater designed according to the
improved ASHRAE standards is $100 for a 50 gallon unit. A flow-through unit
can cost in the neighborhood of $400 (58). The cost of insulating hot water
lines is usually between $0.50 and $1.00 per foot.
Solar Water Heating
Solar water heating can be provided as part of a solar space heating
system or as a separate system. In either case the water temperature attained
from solar heating alone is generally too low for some hot water uses, thus
the solar system functions largely as a preheater; additional heat must be
provided either in a storage heater or at the point of use.
73
-------
TABLE 38. EFFECT OF IMPROVED ASHRAE HEATER DESIGN STANDARDS
hotwater
pilot
heat loss*
total
Electric Heater
Current 1977 %
Standard Standard Reduction
(Btu/day) (Btu/day)
40,000 40,000
8,700 6,100 30
48,700 46,100 5
Gas Heater
Current 1977 %
Standard Standard Difference
(Btu/day) (Btu/day }
40,000 40,000
9,600 9,600
21,300 16,900 21
70,900 66,500 6
* Includes conversion loss and stand-by loss.
Notes: Assumed conditions: water inlet temperature
water outlet temperature
room temperature
hot water use
heater size, gas
heater size, electric
= 60°F
=120°F
= 70°F
= 80 gal/day
= 50 gal
= 66 gal
74
-------
According to the Arthur D. Little study (58), solar water heating
systems designed to provide the least amortized cost per unit of energy
provided would cover from 30 to 50 percent of the thermal requirements for
water heating, depending upon the region of the country and type of struc-
ture. The associated collector areas ranged from 30 to 55 sq ft/dwelling
unit. The solar energy systems considered in the Massdesign study (Table 37)
incorporated water heating units. Over the course of a year's operation
the systems provide a large portion of the water heating energy reqiurement.
However, the costs of the water heating components were not accounted for
separately. Since we do not have costs for individual units we have assumed
the ratios of cost/energy unit supplied which are reported in the Massdesign
work are applicable to water heating (56).
LIGHTING
Two ways to conserve energy in lighting are to make maximum use of sun-
light and to illuminate only the areas which are needed for specific activi-
ties. They can be combined in the placement and design of windows and rooms.
Although all exposures receive adequate light, certain exposures are
more conducive to the use of sunlight than are others. Eastern and western
exposures receive good morning and afternoon sun. However, light from a low
lying sun, to which both these exposures are subject, is difficult to control
and may produce glare and excessive heat. Vertical windows are best for
these exposures. A southern exposure receives the most sunlight. Moreover,
the sunlight is at a high angle which does not produce glare and offers, in
conjunction with high window placement, the best opportunity for lighting a
whole room. Horizontal windows are best for this exposure. Northern exposures
receive no direct sunlight.
When sunlight is not available and a specific task has to be done it
is best to light the immediate area rather than the whole room. For normal
living space in which no specific task is being done, light should be kept at
a minimum. Lighter finishes on ceilings, walls, floors, and even furniture
can increase the utilization of available light by providing greater reflec-
tances.
There are several kinds of bulbs used for lighting, although in resi-
dential use incandescent and fluorescent are the most popular (see Table 39),
Long lasting incandescent bulbs should be used sparingly. They are very
energy inefficient compared to "normal bulbs." Whenever possible, fluorescent
should be used rather than incandescent since the former is three times more
energy efficient than incandescent.* During the cooling season lighting will
However, fluorescent lighting may be harder on the eyes, one reason being
that it is nearer the blue of the spectrum. The focal point of blue light
is slightly in front of the retina and so some blurring occurs. In many
buildings fluorescent light has been made slightly yellow, thereby bringing
it nearer the red end and easing its effect upon the eye. But when this
is done, efficiency decreases.
75
-------
TABLE 39. LIGHT SOURCE EFFICIENCIES
Incandescent Lamp
60-watt general service lamp
100-watt general service lamp
14.3 lumens/watt
17.4 lumens/watt
Fluorescent Lamp
2-24 inch cool white lamps
2-48 inch cool white lamps
50 lumens/watt
67 lumens/watt
HID Lamps
400-watt phosphur coated mercury lamp
400-watt metal halide lamp
400-watt high pressure sodium lamp
46 lumens/watt
74 lumens/watt
100 lumens/watt
for outside use.
76
-------
contribute to the heating load. A rough estimate is that for each kwh of
lighting used an extra one-half kwh of air conditioning will be required.
KITCHEN
Because of the way in which the kitchen function has been defined, it
encompasses the use of more types of resources (electricity, gas, and water)
and the generation of more residuals (gaseous, liquid and solid) than any
other function. On the other hand, except for the reduction in solid resi-
duals and the elimination of the gas pilot from stoves, most conservation
measures will produce only very marginal improvements.
Water, Liquid Residuals (and Some Energy)
Water use in kitchen sinks is largely determined by the amount of water
needed for rinsing fresh foods, cooking, or for washing dishes and utensils
manually. Aerator-type nozzles might reduce water use if the faucet is
turned on to a moderate degree; however, if these devices encourage maximum
strength use, it is not clear that they save water. Double sinks may reduce
water consumption. Timed faucets, or faucets which operate only by hand
pressure, are water-saving devices which are not found very frequently in
kitchens; their use for rinsing fresh foods seems to be quite impractical.
The volume of water used by garbage grinders can be reduced if the unit
is used only when filled with food residuals. The weight of pollutants dis-
posed of into the sewer is not affected by this practice, of course. The
energy used by the grinder is relatively unimportant.
Dishwashing is an important source of water and energy use and waste-
water generation. The main difference between hand washing dishes and using
an automatic dishwasher is in the use of electricity, if the machine is
utilized only when full. Otherwise, the two methods of dishwashing are com-
parable (see Section 5). The washer consumes electrical energy in heating
the water from the central hot water system to the required temperature (about
155°F in models with "sani-feature"), in drying the dishes with hot air, and
in operating the pump. Perhaps a 30 percent reduction in electricity use can
be achieved by cool drying. Also a reduction of the water temperature in the
washing cycle could save energy if washing is judged to be effective and
sanitary at lower temperature.* Water can be conserved by collecting the water
used in the final rinsing, and by applying it for lawn irrigation. However,
the relatively small amount of water saved (say about one-half of the total
water used in the dishwasher) would not offset the replumbing cost.
Energy
Important users of electricity are the refrigerator and freezer; together
they represent far more than half of the electrical energy used in the kitchen.
Two methods are available to reduce the energy requirements in existing units:
(1) pipe waste heat from the compressor to the outside of the box; and
Commercial dishwashers, for example in restaurants, operate at a temper-
ature of 180°F.
77
-------
(2) install an on-off switch for the anti-condensation heater in those units
which have them. Each will reduce the use of electricity by about 10 per-
cent. In selecting a new unit it is obvious that all other things being
equal, the more insulation a unit has, the more efficient it will be. Project
Independence claims that an increase of insulation from one and a half inches
to two inches increased efficiency by 20 percent (14).
Significant improvements in efficiency are also obtained by keeping
condenser coils clean and the door gaskets in good repair, by reducing the
number of times the door is opened, particularly in a household with children,
by keeping the unit fully stocked,* and by purchasing a unit no larger than
necessary for the household.
In the cooking activity, the stove and oven are the important users of
energy. The biggest difference between gas and electric ranges is the fuel
wasted by the pilot light on the gas stove. The American Gas Association
estimates that the pilot light uses one-third of the gas consumption of the
ranges (8); Consumer Report (15) estimates between 20-50 percent. It is
possible to replace the gas pilot light with an electric ignition device.
Efforts are being made to ban the sale of appliances equipped with gas pilot
lights. The state of California, for example, has already instituted such
a ban (61).
In the case of ovens, insulation is again important. Self-cleaning ovens
are required (for reasons of safety) to have more insulation that standard
ovens. Although the self-cleaning models use less energy for baking and
roasting they use more for cleaning. Nonetheless, since conduction losses
generally account for about 60 percent of oven heat loss, energy savings can
be obtained with self-cleaning models by disconnecting the self-cleaning
feature. Again, elimination of the gas pilot can save energy. A gas range
with an electric ignition burner and oven can cost $40 to §50 more than a com-
parable model without this feature (62). Another item which may reduce energy
use is a small glass panel on the oven door which prevents unnecessary heat
loss by allowing the user to observe the cooking process without opening the
door. However, heat loss through the window may be greater than through a
solid door, partially offsetting any savings.
Many appliances in the kitchen give off waste heat: oven, dishwasher,
refrigerator, stove. During the summer it may be advantageous to lower waste
heat loads in the kitchen by proper ventilation. In the fall and the winter
the waste heat from the kitchen automatically reduces the space heating load.
Solid Residuals
The kitchen and the other functions produce solid residuals in the form
of paper, glass, metal, food wastes, and other miscellaneous items. Garbage
A unit that is filled with food requires less electricity to operate than
one which is empty.
78
-------
grinders convert about 75 percent of the organic component to liquid residuals.
Refuse compactors reduce the volume needed for storage, but the total weight
is not reduced. The fact that a refuse compactor is more effective in reduc-
ing the volume of certain materials, such as metal containers and other bulky
materials, might have an influence on the weight and composition of the house-
hold's solid residuals.
Mechanical devices and physical changes in refuse storage areas are not
likely to significantly reduce the generation of solid wastes. Solid residu-
als comprise the one category where measures exogenous to the household (e.g.,
the packaging practices of vendors, the passage of such legislation as the
"bottle bill," the provision of separate collection, and the relative prices of
virgin and recycled factors of production) and attitudes and behavior of mem-
bers of the household (e.g., preference for prepared food and willingness to
participate in recycling programs) are more important than physical measures
designed to control residuals generation. As a result it is difficult to
estimate what kinds of reductions in waste generation might be anticipated.
Nonetheless, below we will show how the factors listed in Table 6 of Section
4 can contribute to a reduction in solid residuals generation.
Inconvenience plays the most important role for a household involved in
any program of solid residuals recovery. Finding the space to store the
residuals and the time to separate and recycle them is inconvenient; out of
pocket costs are minor. Table 40 summarizes monthly space, time, and cost
requirements of a household to recover glass, tin/bi-metals, aluminum, and
newspaper. The estimates of time (which seem to be very much at the low range)
and costs are derived from a study of source separation and recycling programs
across the country (63). Some general trends could be observed: the more fre-
quent the collection, the higher the participation rate; participation rates
in programs increase with duration of the programs. For example, a program in
Fort Worth, Texas indicated a participation rate of 25 percent for a newspaper
collection frequency of twice per month, but a rate of 40 percent for once a
week collection. After inception, the program revealed an annual increase in
the participation rate of 18 percent. Collection on the day of regular solid
waste collection is also basic for a stable participation rate. A mandatory
source separation ordinance will contribute to an increase in the participa-
tion rate.
In the following tables of potential measures to reduce the solid residu-
als generation rate (Tables 41 through 43), every measure was given a rating
of "inconvenience" to the household, as perceived by Meta Systems' partici-
pants in recycling operations and as interpreted by the review of related
literature (63, 64, 65, 66). The rating depends essentially on the amount of
resource input, especially time required by the various measures. However,
because time estimates can vary so widely and because other considerations
(e.g., existence of collection centers and frequency of collection) are also
important we did not use amount of time as the rating which appears in the
tables. Rather we gave each conservation measure a letter rating; an A
reflects no inconvenience and a D indicates considerable inconvenience.
We felt four ratings were sufficient in an area which is so difficult to
evaluate in "average" terms; more ratings would only confuse the issue by
79
-------
TABLE 40. MONTHLY SPACE, TIME, AND COST REQUIREMENT FOR A HOUSEHOLD
FOR RECOVERING SOLID RESIDUALS*
Storaget
Time (min/month) for Preparation
Range of
Residuals1" Requirement Remove Reduce Transport Costs***
(Ibs/month) (sq ft /month) Clean** Contaminants Volume Bundle (in house) ($/month)
00
o
Glass 18.0 2.2 9.6 2.4
Tin/Bi-Metal 6.8 1.6 - 2.8 9.2 4.4
Aluminum 1.2 1.8-1.9 2.8 0.4
Newspaper 48.8 3.3 N.A. 0.4
0 N.A. 6.4 0-0.005
8.8 N.A. 5.6 0-0.005
0.8 N.A. 1.2 0-0.002
N.A. 9.2 2.4 0-0.011
Based on: SCS-Engineers (63)
f Assumed 3.4 persons/household on the average.
$ Monthly accumulation of materials in storage containers of a makeshift nature (e.g., cardboard boxes
or grocery bags); lower value of ranges indicates that volume of materials has been reduced; newspapers
are stacked.
** Includes time for material sorting.
*** Incremental (1973) costs to households for resources used (while separating and preparing materials);
including water used for cleaning, energy used if metal container volume reduction is accomplished with
can opener, and twine used when bundling newspaper; lower range indicates zero preparation costs; costs
in parentheses give costs of container. No value is given to home labor or inconvenience.
-------
TABLE 41. MEASURES INFLUENCING SOLID RESIDUALS GENERATION
% Reduction Level of In-
Administrative/Institutional (of component weight) convenience to Household
Garbage Grinder Organics 65-75 A
Separate Central Collection:* B-c
Paper 35 (15)
Glass
} 60 (25)
Metals
Bottle Bill: B
Metal 15-20
Glass 25-35
Restricting Advertising: A
Mail
Paper } 5-10
These estimates are based on unpublished data of EPA regarding their
source separation and collection programs in Marblehead, Massachusetts,
a relatively wealthy suburb, and Somerville, Massachusetts (numbers in
parentheses), a blue-collar city near Boston with a higher percentage
of rental units. In Somerville, just clear glass instead of all glasses
was separated.
81
-------
TABLE 42. MEASURES INFLUENCING SOLID RESIDUALS GENERATION
% Reduction Level of In-
Physical/Technological (of coogonent weight) convenience.to Household
Storage space (in MduH)*
Paper 15-25 B (C)t
Glass
25-35
Metals
Separate Chutes (in MduHjf
Glass & Metals 70-80 A
Paper Bundled 30-40 B (C)**
* These values have been developed from the data on Somerville, Mass.,
because the city has a high percentage of multi-family units: central
collection is assumed.
t If a storage facility is provided for every floor, the inconvenience (B)
of recycle is much smaller than the inconvenience (C) associated with
carrying the material into the basement.
t Based on speculation of a dual chute system: glass and metals, and
others (except newspapers), respectively.
** See t above.
82
-------
TABLE 43. MEASURES INFLUENCING SOLID RESIDUALS GENERATION
% Reduction Level of In-
Behavioral (of component weight) Convenience to Household
Use ef garbage grinder organics 65-75 A
Participating in voluntary C-D
recycling operation*
Paper 10-20
Glass 10-40
Metals 15-50
Others 0-6
Compost heap use B-C
Organics (except meat) 30-60
Garden waste 70-85
Use of advertising mail as
scratch paper 2-3 B
Reuse of packaging material paper 1-3 B
Conscious efforts of purchasing products
generating fewer residuals 3-5 C-D
Upper estimates are based on the best year of the recycling operation
in Wellesley, Mass., one of the most successful voluntary operations
in the United States; it is assumed that a recycling center is con-
veniently located in the neighborhood.
83
-------
arguments about scaling. Rating A implies essentially that changes of the
household's daily routines are not required. Rating D is given to those
tasks which require the largest inputs of household resources (e.g., separat-.
ing materials and taking them to a recycling station), Ratings B and C cover
largely the efforts at home, such as separating, storing and bundling materials
to be picked up at curbside as part of a regular collection service. We feel
that the inconvenience increases with the number of materials separated,the
time required to separate them, and the space needed to store them. If only
newspapers are separated, the time and space requirement is relatively minor.
If, however, newspapers, metals and glass are separated,the space requirements
increase and if the materials must be taken to a. collection point, time
increases also. Thus, we feel that a rating of B is appropriate for separa-
tion of one fraction, such as newspapers; should the tasks of separating other
materials be added, the inconvenience might increase to C, especially in small
single family and multi-family units. The storage space required becomes
significant.
The rating of the impact of the "bottle bill" is difficult. Many people
perceive it as very inconvenient at the moment of its inception; but only stor-
ing the containers is really inconvenient because return can be combined with
purchase of new containers. Therefore, we have used a rating of B.
Use of compost heaps must receive a range of ratings. Given small lot
sizes and the intention of efficient use {i.e., large reductions in volume of
material} of compost heaps which requires the proper mix of materials, control
of the level of humidity and insurance of aerobic conditions, would imply a
rating of C. If the compost heap is largely a dumping place for grass clip-
pings and leaves on a large lot (see Outdoors), there might be little incon-
venience. The rating might be B or even A.
In general, it is difficult to compare the inconvenience levels as they
are perceived by citizens. But, we feel that our attempt of an average rating
and its discussion should provide some guidance.
WASHING AND CLEANING
The two major users of resources under this function are the washing
machine (water) and the dryer (electricity or gas). The washing machine also
contributes to the liquid waste load.
In washing, water can be conserved by the use of water level settings
appropriate for the size load being washed. If the machine does not have
level control the user should wait for a full load to accumulate. One device,
known as a "suds-saver," reuses wash water by discharging it to a sink where
it is stored for use in the next washing cycle.
Because the washer's direct electric energy use is so small, the princi-
pal energy conservation measure is the reduction in hot water use. This can
be achieved both through a reduction in overall water use and through the use
of warm or cold rather than hot water for washing and of cold water for
84
-------
rinsing.* Control over residuals loads is limited to the use of a "suds-
saver" and to the selection and use of detergents.
For dryers, decreasing energy use depends to a large extent on
behavior. Conservation measures include waiting for full loads to accumu-
late, cleaning the lint filters regularly, drying similar type fabrics
together, running multiple loads in succession to avoid having to reheat
the dryer before each load, avoiding "overdrying" of fabrics, and keeping
the dryer in a heated room. It may also be possible to increase the in-
herent efficiency of the units by providing additional insulation and
tighter seals."''
It has been suggested that waste heat from dryers be employed to
heat rooms by allowing for indoor venting during the heating season.
Because of the high moisture content of this gas, and the presence of fine
lint particles, special air filters would be required and excessive humidity
could be a problem.
BATHROOM
Water use can be reduced significantly, but little opportunity exists
to reduce or eliminate wastewater residuals associated with bathroom
activities; the options are more related to media trade-off (e.g., waterless
vs. water-using toilet) and alternate methods of treatment and disposal
(e.g., septic tank or composting toilets vs. centralized treatment).
Toilets
Major savings in water can be achieved in this area. Many devices exist
which reduce the volume of water used in conventional toilets by as much as 90
percent. The shallow trap toilet, which is similar in appearance and cost to
the conventional toilet, is designed to use approximately one-third less water
than the conventional toilet. Dual flush toilet devices can convert conven-
tional toilets to a two-cycle operation. One flush is for liquids and the
other for solids. Two such devices are the econo-flush and the sink-bob
toilets. The Saveit water saver device requires modification of the conven-
tional toilet; the result is a reduced flush for both cycles. Data have indi-
cated this reduced flush may not be sufficient to adequately remove solids
(24). All devices, except the Saveit which needs modification for the solids
to flush, appear satisfactory to U.S. consumers (24). A water use and cost
summary for such devices and others is shown in Table 44.
* Some cycles, such as the permanent press cycles, have a larger water use
in the pre-rinse cycle in order to keep the clothes wet at all times.
Thus the proper selection of washing cycles affects not only cleaning
efficiencies, but water use as well.
t The fact that electric units are more efficient than gas seems to indi-
cate that manufacturers do respond to energy prices and that there is
room for improving the operating efficiency of dryers.
85
-------
TABLE 44. WATER CONSERVATION DEVICES FOR BATHROOM (TOILET)*
Device
Cost ($)
Water Used
Toilets
Conventional toilet
close-coupled
Conventional toilet
one piece
Conventional toilet
one piece w/flush meter valve
Conventional urinal
w/water storage tank
(residential)
Shallow trap toilet
Tank flushing valve
Variable flush attachment
Dual flush
Pressurized flush toilet
Pressurized tank toilet
Controlled volume
flush toilet
Wastewater recycling
toilet
Oil flush toilet
60t(l974)
180-480t
40-125t(plus
75 for tank)
70
few dollars
5m
16*
300"*"
60 for air
compressor
5-7 gal
6-8 gal
4 1/4 gal
1-4 gal
1-4 ga]
3-3.5 gal
2-4 gal for partial flush
2 quarts/flush
40 for tank 2-2 1/2 gal
not given
single:
1400-1650
double:
2400-2800
1-3 pints/flush
m
.m
2500 not installed
without inciner-
ator
m
(Footnotes on next page)
86
-------
TABLE 44 (CONTINUED)
Device
Cost (?)
Water Used
Incinerator toilet
Vacuum toilet
Composter toilet
Packaging toilet
Freeze toilet
Chemical toilet
Leak signalling ballcock
395 (1972) 8 ounces for weekly cleaning
75 installation
1.3 quarts/flush; 6% of water
used in conventional toilets
t
950 not in- 0
stalled, in-
cluding toilet
stool and gar-
bage chute
320T (estimate 0
for delivered
unit in New
York area)
60 and up for 4 gal/60-80 uses
fresh water
flusht
250 for water
recirculating"''
6-10f
* Milne, M. (41)
,t study cost estimate (41)
m manufacturers cost estimate (41)
86 (a)
-------
The Clivis Multrum, a waterless toilet which also accepts kitchen garbage
and produces a dry, black, odorless humus reduced to 5 percent of the input
volume, was first introduced in Sweden, in approximately 1954. The device has
not yet been well-received in the U.S. In some installations odors may be a
problem and supplemental heat is sometimes necessary to maintain the tempera-
ture at 90°F (32°C) which increases energy use and cost. The complete system
including recommended external equipment costs $2,000-$3,000 (1974 dollars)
(29).
The Lilyendahl system uses air rather than water to transport wastewater,
requiring only 0.5 gallons per toilet flush. The system's principal compon-
ents are a waste receiving tank and a vacuum pump. Current use in Sweden and
the Caribbean Islands is limited to commercial establishments. As an
individual wastewater treatment system it costs $1,520 (1974 dollars); however,
a system installed in a development of 100 houses or more is estimated to cost
$295 per household (29) .
Wastewater residuals from toilets cannot be reduced but transport-treat-
ment options are available. Collection systems can be relieved in stress
areas by utilizing water saving toilets? however, consideration must be given
to the potential impact on conventionally designed sewers and wastewater
treatment plants, since the solids content of the resulting wastewater would
be substantially increased.
Bathing
Flow limiting heads for showers can reduce rate to 2.5 gpm and 3.5 gpm;
however, survey results (29) indicate some user dissatisfaction with the lower
rate, 2.5 gpm. These devices cost less than $15 installed (1974).
Water savings in bathing can also be achieved by the thermostatic mixing
valve. It maintains a constant temperature level by controlling the hot and
cold water mix. The bather can reduce the shower flow rate while soaping
without need of temperature regulation. The device costs $100 installed (1974
price). An extensive list of devices, range of water used, and costs is
found in Table 45.
Reuse of the bathing water and other gray water for toilets can reduce
water use by up to 40 percent. Total installed costs of a reuse unit (1974
dollars) is $325.00 (29). Reuse of bathing and lavatory wastewater for bath-
ing requires on-site conversion of the residuals media (i.e., liquid to solid);
the result is a decreased hydraulic and wastewater residual loading but may
increase solid waste residuals (e.g., a filtering unit or cartridge used to
remove residuals needs to be disposed, but a diatomite type filtration unit
will increase the solids loading to the sewer system during backwashing).
Lavatory
Lavatory water use can be reduced by separate hot and cold water faucets,
which may encourage using the basin to catch and mix water to the desired
temperature, in contrast to a single mix-type faucet which encourages contin-
ual water flow. Another device is the spring or timed faucet that automati-
cally shuts off the flow at short intervals. Faucet aerators may decrease
87
-------
TABLE 45. WATER CONSERVATION DEVICES FOR BATHROOM* (SHOWER, BATH, SINK)
Device
Cost($)
Water Used
Bathing and Personal Hygiene
Conventional faucet
Flow controls -
sink, shower
Aerators and spray tapes
Self-closing mixing valves
Thermostatically controlled
mixing valve
Pressure balancing mixing
valve
Air-assisted shower head
Bidets
Sinks and Bathtubs
Functionally designed sinks
and bathtubs {water saving)
0.75-20 '
aerators:
1-5t when
purchased
separately
3 gal/min
aerators: 0.75 gal/min
spray taps: 1-2 gal/min
comparable
to conventional
equipment cost
60t installation
"cost same as for
conven. valve
45t installation
cost same as for
conven. toile t
275 installed m 1/2 gal/min
70
,t
hold 1-2 gal
limited demand
means initial
price somewhat
higher than con-
ventional models
sinks: less than 1 gal
tubs: less than 50 gal
* Milne, M.(41)
t study cost estimate (41)
m manufacturers cost estimate (41)
88
-------
the water use at the lavatory; estimated reductions are one to two gallons per
household per day (24). Contrary to this is the belief that the aerator
reduces splashing and water use could actually be increased. This device is
not as costly at $2.
OUTDOORS
The only resource used in significant quantities outdoors is water. The
most important residuals are solid waste and stormwater runoff. To a large
extent the one activity which accounts for water used, the solid residuals
generated, and the quantity of runoff is landscaping. Consequently changing
landscaping and gardening practices can lead to substantial reductions in
water consumption and residuals generation.
Water
Although outdoor use can amount to over half of the water utilized by a
residence, little attention has been given to conservation measures. Approxi-
mately 90 percent of the outdoor water use goes to lawn and garden and some of
it is wasted in overwatering. A recent California study estimated that over-
watering accounted for slightly less than 20 percent of the outdoor residen-
tial water use in the state in 1972 (38). There are some devices which can
reduce overwatering if properly employed. Trigger type nozzles, soil moisture
indicators, timed sprinkler systems, and drip irrigation systems can reduce
water use. These and other devices are listed along with ranges of costs in
Table 46 . We have made no estimate of water savings, but the study mentioned
above concludes that a well-controlled, timed sprinkler system would reduce
overwatering by 50 percent (38) .
Another approach to reducing irrigation requirements is the utilization
of native vegetation and low water using plants to landscape a residence. In
some regions of the country such a practice could reduce outdoor water use by
more than 50 percent.
Solid Residuals
Most solid residuals from landscaping and gardening can be composted and
reapplied to the soil as a fertilizer or conditioner. Composting grass clip-
pings, leaves, and other organic yard wastes can reduce the weight of solid
waste residuals by as much as 30 percent at least during the summer and the
fall. This requires, however, a composting operation closely controlled by
the household. Composition of materials, level of humidity, and method of
covering the heap are determinants of the quality of the operation (see
above). If composting bins are used, depending on the size and design they
can cost between $10 and several hundred dollars. Also ready-made units are
available. They range in price from §75 to several hundred dollars.
Stormwater Runoff
Runoff from residential lots can be decreased by eliminating impervious
surfaces, by landscaping with vegetation which increases interception and
infiltration of precipitation and retards overland flow, and by directing run-
off from roof to dry wells rather than sewers and gutters. Quantitative
relationships have not been developed on a small scale but on the basis of
aggregated data Lager and Smith have estimated that the residuals in the runoff
can be reduced by as much as 25 percent (67).
89
-------
TABLE 46. LAWN AND GARDEN IRRIGATION DEVICES WHICH
MAY CONSERVE WATER
Device
Hose Attachments
Cost <$)
1-40
Ins tantaneous
Moisture Indicator
1-25
Tens iometers
150
Lawn Sprinkler Timer
70 and up
Drip Irrigation System
7 - several hundred
- hose attachment
7-20
- installed system
300 -800
(depending on area of
lawn and quality of.
system)
90
-------
MAINTENANCE
Automotive maintenance is the only activity considered to be a signifi-
cant resource user or residuals generator under the maintenance function.
Unfortunately data which would provide the basis for estimating the magnitude
of water use and wastewater generation have not been collected. The amount of
water used in washing a car can be reduced with a trigger type nozzle or the
use of a bucket. Any runoff associated with washing would be reduced also.
Discarded lubricating oil presents a problem similar to that faced with
recoverable solid residuals—the broad distribution of very small quantities
of a material which can be economically reclaimed only once it has been
collected. The collection depends on individual willingness to transport the
oil to some central location where sufficiently large quantities can be stored
and reclaimed.*
SUMMARY
In this section we have presented a wide range of conservation measures
and suggestions for practices which may reduce resource use and residuals
generation. In most cases we have provided the range of savings to be expec-
ted with the various measures, devices and practices. Where possible we have
given cost estimates. Although we have focused our attention on the major
resource using functions and activities we have tried to include some examples
of simple and inexpensive devices which, when used properly, can lead to
noticeable savings. In the next section we will show how the material pre-
sented above can be employed to estimate reductions in resource use and
residuals generation in the context of completely specified baseline cases.
For a further discussion of the issues associated with collection and
reclamation of used oil, see Irwin, W. A. {68).
91
-------
SECTION 7
RESOURCE AND RESIDUALS BASELINES AND THE IMPACT
OF CONSERVATION MEASURES
INTRODUCTION
We intend to develop two hypothetical baselines — one "high" and one
"low" — of resource use and residuals generation. Our purpose is to provide,
in a more concrete context, some perspective on the use and generation figures
presented in Section 5 and the conservation measures in Section 6. Also, we
wish to illustrate a method for determining the relative merits of conservation
measures and their attractiveness to homeowners.
The baselines are constructed for single family residences and the differ-
ences between the high baseline and the low baseline are more a matter of physi-
cal differences in the structures (e.g., amounts of insulation, efficiency of
the heating system, and the presence of resource using devices) than behavioral
differences of the occupants. Two baselines are selected to illustrate the
range of options available and the consequences of implementing conservation
measures depending on assumed use levels.
BASELINES
The baselines are constructed for a single family detached house on a one-
quarter acre lot. In each case the house is occupied by four persons (two
adults and two children) and is assumed to be located in southern New England.
Some of the characteristics shared by both baseline houses are listed in
Table 47.
Energy use and gaseous residuals generation for each residence are pre-
sented first, followed by the water use and liquid residuals estimates and the
solid waste baseline figures. Table 48 contains the specific characteristics
necessary for the obtaining energy baselines. As can be seen from the table
the primary differences are found in levels of insulation, thermostat settings
and energy using devices. The characteristics which are important for deter-
mining the water use and liquid residuals baselines appear in Table 49 and
the characteristics and assumptions needed to calculate the solid residuals
baselines are contained in Table 50 .
The calculations which must be made to develop the baseline estimates are
straightforward, but tedious, and are not presented in this section. However,
in order to provide the information necessary to reproduce the estimates, an
example of the procedure we have used is given in Appendix E.
92
-------
TABLE 47. SOME CHARACTERISTICS OF BASELINE "SINGLE
FAMILY HOUSE"
Structure Type; One-story detached; no basement; 1,500 sq ft of
living space
Lot Size; 1/4 acre
Location; Southern New England (according to Table B-2: 5,000 degree
days/year; average outdoor heating season temperature: 45°F;
400 cooling hrs/yr; average outdoor cooling season temperature:
85°F)
Size of Household: 4 persons (2 adults and 2 teenage children)
Energy and Gaseous Residuals Baselines
For the energy baselines the estimates of use (on an annual basis) by
function, for both the high and low baseline, appear in Table 51 . in both
cases the most important function is space heating and the second most import-
ant is water heating. Together they account for over 80 percent of the energy
used. All other functions, with the exception of cooling in the high baseline,
use very small quantities of energy. There is not one which contributes more
than four percent to the total.
The transformation of the requirements for energy into gaseous residuals
is performed using the ratios in Table A-5. Only those functions which actu-
ally convert fuel to heat in the residence (i.e., space heating, water heating,
and kitchen range) generate gaseous residuals. The results are found in
Table 52 . Naturally the primary contributor is space heating.
Water Use and Liquid Residuals Baselines
In the water use baselines, the most important water using activities—
toilet and bathing—occur within the bathroom function (Table 53 ). In the
low baseline the toilet accounts for 33 percent of indoor use and bathing 22
percent. In the high case the shares of indoor use are 38 percent and 19 per-
cent respectively. Some outdoor water use is included in the high baselines—
lawn watering and car washing. Lawn watering accounts for almost all of the
outdoor use (89%) and 20 percent of the total (indoor plus outdoor) water use.
In the liquid residuals baselines it is assumed that none of the water
used indoors is consumed, i.e., all becomes part of the liquid residuals load.
In the case of outdoor use we assume that the irrigation water does not run
off, but that the car wash water does and that it enters the sewer system.
Estimates of organics and nutrients which become part of the liquid residu-
als stream appear in Table 54. The only real differences between the two
93
-------
TABLE 48 . CHARACTERISTICS OF BASELINES FOR ENERGY USE
Low Energy Use House
Heating
Built to FHA '73 specifications; gas forced-air
heating; 75 percent efficiency; thermostat
setting 68°F (reduced to 62°F for 6 hours over-
night) ; all rooms heated.
Cooling
No central cooling system.
Water Heating
Central supply and storage system; gas furnace
with pilot light; 50 gallon tank; inlet temper-
ature 60°F; outlet temperature 120°F; ambient
air temperature 68°F.
Kitchen
Gas range (stove/oven) with pilot light;
refrigerator (manual defrost).
Washing/Cleaning
Washing machine and dryer (each used once
a day).
Bathroom
Miscellaneous small energy uses.
Living/Entertainment
Black and white T.V.; radio.
High Energy Use House
Heating
Built to FHA '65 specifications; gas forced-air
heating; 65 percent efficiency; thermostat setting
of 72°F (no reduction overnight); all rooms are
heated all the time.
Cooling
Central cooling system; thermostat setting of 75°F
(efficiency of 65 percent).
Water Heating
Central supply and storage system; gas furnace with
pilot light; 50 gallon storage tank; inlet temperature
60°F; outlet temperature of 140°F; and ambient air
temperature 70°F.
Kitchen
Appliances include a self-cleaning gas range (stove/
oven) with pilot light; refrigerator (frost-free),
separate freezer (frost-free feature); dishwasher;
and other appliances.
Washing/Cleaning
Washing machine, electric dryer, and miscellaneous
small appliances are available; washing machine and
dryer are each run once a day on the average.
Bathroom
Miscellaneous small energy uses.
Living/Entertainment
Color T.V. (with instant-on feature) and radio/
stereo equipment.
-------
TABLE 49 . CHARACTERISTICS OF BASELINES FOR WATER USE
AND WASTEWATER AND LIQUID RESIDUALS GENERATION
Low Water Use House
Indoors j
High Water Use House
Kitchen:
-sink
Bathroom:
-bath tub
-conventional toilet (4 gallon
tank)
-sink
Kitchen:
-sink
-garbage grinder (2 uses /day)
-dishwasher (2 loads/day)
Bathroom:
-two bathrooms, first with
tub & shower, second with
shower only
Each with conventional
toilet (6 gallon tank) and
sink
Other:
-washing machine
other day)
(once every
Other:
-washing machine
(once a day)
Outdoors
-no lawn watering
-car washed in car wash
-18,500 sq ft of lawn watered
-car washed once every month
95
-------
TABLE 50. FACTORS LEADING TO LOW AND HIGH BASELINE
SOLID RESIDUALS GENERATION
II
III
Low
grinder ordinance
separate collection
of cardboard, paper,
glass and metals
at days of regular
collection
absence of garbage
grinder
gardening efforts
no compost heap
citywide recycling
center
High
grinder ordinance
factor price (paper
good but variable,
aluminum 17C/lb)
separate collection
of newspaper (I/
month) (a little
unreliable; no good
advertisement)
no compost heap
recycling center
available (but
only on voluntary
participation
except for news-
paper)
I = administrative and institutional factors
II = physical and technological factors
III = behavioral and personal factors
96
family eats regularly at
home; attempts to keep
use of precooked meals at
a minimum
non-returnable beer and
soft drink cans
regular local morning
newspaper (not very big);
Sunday newspaper
separation of newspaper
and glass and metal at a
frequent level (2 per
month)
some "junk mail" is used
for "scratch" paper; all
other paper fractions are
discarded.
family eats regularly at
home; typical food being
a mixture of fresh and
precooked meals
all organics are ground
by garbage grinder
non-returnable beer and
soft drink cans
regular local morning
newspaper (not very big):
Sunday newspaper
Occasional separation of
newspaper (1/3 month). If
they are not picked up
they get thrown away with
regular collection.
-------
TABLE 51 . ENERGY BASELINES
Low Use High Use
Millions Portion Millions Portion
Btu/yr of Total Btu/yr of Total
Space Heating 118.3 0.75 266.4 0.73
Cooling - - 28.6 0.08
Water Heating 24.5 0.16 35.8 0.10
Lighting 1.7 0.01 6.0 0.02
Kitchen 7.0 0.04 16.9 0.04
-Range (plus pilot) [4.0] [4.8]
-Dishwasher [-] [1.2]
-Refrigerator [2.5] [4.4]
-Freezer [-] [5.0]
-Miscellaneous [1.5] [1.5]
Washing/Cleaning 5.6 0.03 8,3 0.02
-Washing machine [0.3] [0.5]
-Dryer [5.0] [7.5]
-Miscellaneous [0.3] [0.3]
Bathroom
-Miscellaneous 0.1 - 0.1
Living/Entertainment 0.9 0.01 2.6 0.01
-Television [0.3] [1.8]
-Radio/Stereo [0.3] [0.5]
-Miscellaneous (hobbies) [0.3] [0.3]
Total 158.1 1.00 364.7 1.00
97
-------
TABLE 52. GASEOUS RESIDUALS (LBS/YR)
Low Baseline
Heating
Water Heating
Kitchen Range
Total
Heating
Water Heating,
Kitchen Range
Total
Particulates
1.1
0.2
-
1.3
Particulates
2.6
0.3
-
SOj). SO 3 CO
0.1 - 2.3
0.5
0.1
0.1 - 2.9
High Baseline
S02 SO 3 CO
0.2 - 5.2
0.7
0.1
Hydrocarbons
0.9
0.2
-
1.1
Hydrocarbons
2.1
0.3
-
N02
9.1
1.9
0.3
11.3
N02
20.6
2.7
0.4
2.9
0.2
6.0
2.4
23.7
98
-------
TABLE 53. WATER USE BASELINES (GAL/YR)
Low Use
High Use
Indoor:
Kitchen
- sink
- garbage grinder
dishwashing
Bathroom
- toilet
- bathing
- sink
Cleaning
- washing machine
- miscellaneous
Subtotal
Outdoor :
Lawn watering
Maintenance
- car washing
Subtotal
Gallons/
yr
8,760
5,840
21,900
14,600
4,380
8,210
1,825
65,515
-
—
-
Portion
of
Sub-
Total Total
.13
.09
.33
.22
.07
.13
.03
1.00 1
-
-
-
.13
.09
.33
.22
.07
.13
.03
.00
-
-
-
Gallons/
yr
8,760
4,380
11,680
43,800
21,900
4,380
16,425
3,650
114,975
29,200
3,650
32,850
Portion
of
Sub-
Total Total
.08
.04
.10
.38
.19
.04
.14
.03
1.00
.89
.11
1.00
.06
.03
.08
.30
.15
.03
.11
.02
-
.20
.02
-
TOTAL
65,515
1.00 147,825
1.00
99
-------
TABLE 54. LIQUID RESIDUALS BASELINE (LBS/YR)
Low Use
BOD5 SS TN TP
Kitchen
sink
- dishwashing
Bathroom
- toilet
- bathing
- sink
Cleaning
- washing machine
TOTAL
29.2
21.9
43.8
14.6
14.6
18.6
142.7
7.7
8.8
65.7
8.8
13.1
3.7
107.8
1.5
1.5
29.2
1.5
—
.8
34.5
1.5
1.5
4.4
-
~
.2
7.6
High Use
BOD5 SS_ TN TP Grease and Oil
Kitchen
- sink 29.2 7.7 1.5 1.5
- garbage grinder 116.8 131.4 1.5 1.5
- dishwasher 21.9 8.8 1.5 3.0
Bathroom
- toilet 43.8 65.7 29.2 4.4
- bathing 14.6 8.8 1.5
- sink 14.6 13.1 -
Cleaning
- washing machine 37.2 7.5 1.5 .4
Maintenance
- car washing .1 .8 - - .2
TOTAL 278.2 243.8 36.7 7.8 .2
100
-------
baselines result from the presence of a garbage grinder, the more frequent
use of a washing machine and the car washing in the high case. In the low
baseline the most important source of residuals is the bathroom function.
However, in the high base the garbage grinder contributes far more to the
residuals load than any other source.
Solid Residuals Baselines
The annual generation figures by component appear in Table 55. From the
total in the table, it can be seen that there is little difference between
the high and low baselines. The primary reason for this is the presence of a
garbage grinder in the high baseline residence which reduces the food com-
ponent of solid residuals by more than an order of magnitude. For all other
components the high baseline has substantial greater amounts of residuals
than does the low baseline.
CONSERVATION MEASURES APPLIED TO THE BASELINES
The application of the conservation measures to the baseline cases is
done in a manner so as to illustrate their range of impacts and costs rather
than to identify only the most cost-effective measures. The energy baseline
is considered first, followed by the gaseous residuals, water, liquid
residuals, and solid residuals baselines. Each resource or residual is taken
separately through the relevant household functions and impacts and cost
estimates are calculated.
Energy
Heating and Cooling—
The first measures considered are conventional means of reducing heat loss
and fuel requirements. The impact of six modifications to the shell of struc-
ture are investigated alone and in conjunction with improving the burner effi-
ciency by proper maintenance and lowering the temperature setting on the
thermostat. The modifications, labelled A through F, are outlined in
Table 56. They proceed from very modest additions of insulation to sub-
stantial increases in the thickness of insulation and the inclusion of storm
windows.
We assume that proper maintenance of the burner costs $25/year and allows
the heating system to operate at an 80 percent efficiency. In assessing the
effect of lowering the thermostat we assume that indoor temperature is kept
at 64°F.
The heat loss calculation method described in Section 5 and the incremen-
tal heat loss reduction and costs presented in Section 6 are used to compute
the annual energy savings in Btu's per year and their associated total costs
101
-------
TABLE 55. SOLID RESIDUALS BASELINES
Component
Food
Paper
Glass
Metals
Miscellaneous*
Garden
Total
Low Baseline
Amount Portion of
(kg/yr) Total
High Baseline
Amount Portion of
(kg/yr) Total
540
394
204
102
175
336
.31
.22
.12
.06
.10
.19
29
511
423
204
292
336
.02
.28
.24
.11
.16
.19
1,751
1.00
1,795
1.00
Includes plastics, rubber, leather, textiles, building materials, etc.
102
-------
TABLE 56. STRUCTURAL IMPROVEMENTS TO REDUCE HEAT LOSS
Modification
A increase by 1" insulation in roof
B increase by 1" insulation in walls
C add storm windows throughout
D increase to 6" insulation in roof
E increase to 6" insulation in roof and add storm windows
F up to 24" insulation in roof, 5 5/8" in walls, storm
windows and insulation around floor (foundation)
103
-------
and annual costs.* The annual costs are then divided by the annual energy
savings to provide an indicator of the relative effectiveness of the conser-
vation measures. The results of these calculation appear in Tables 57 and
58.
For the low baseline, the addition of one inch of insulation in the ceil-
ing or walls leads to a fuel savings of slightly more than 6 percent. The
installation of storm windows results in a savings of almost 20 percent.
Increasing insulation to 24 inches in the ceiling and 5 5/8 inches in the
walls, adding insulation to the foundation, and installing storm windows can
in the low baseline bring about a 55 percent reduction in fuel requirements.
Looking at the ratios of annual costs to annual fuel savings it can be seen
that they increase rather dramatically going from modification A to modifi-
cation F. Nonetheless, given the current cost of natural gas to the consumer—
an average cost between $3/106 Btu and $4/106 Btu—only modification F would
appear to be unreasonable. In noting this, we recognize that fuel prices
are likely to increase dramatically and also that using an average cost for
gas ignores the fact that currently most residential customers face a decrea-
sincr block rate. The increase in prices will make the more expensive conser-
vation measures attractive, while decreasing rates will make the marginal
improvements (e.g., the last few inches of insulation) less attractive.
In the case of the high baseline the first inch of insulation in the ceil-
ing or in the walls can reduce the fuel requirement by approximately 11 per-
cent. The effect of storm windows is equivalent to the first inch of insula-
tion, but more expensive. Going to the highest level of insulation considered
can reduce fuel requirements by almost 60 percent. Using the gas prices
given above all the modifications would be attractive to a household.
The effects of a burner maintenance program and a lower thermostat setting
depend on what physical improvements have been made. By themselves (i.e.,
given the baselines) , the former lowers the fuel requirement by 6 percent
(7,1 x 106 Btu) for the low baseline and by 19 percent (50.6 x 106 Btu) for
the high baseline and the latter by 12 percent (14.2 x 106 Btu) in the low
case and 30 percent (78.9 x 10° Btu) in the high. When the residences are
well insulated (e.g. modification F) the maintenance program and the lower
thermostat setting result in much lower savings. In the low baseline given
modification F, the maintenance program reduces the fuel requirement by 3
percent (3.4 x 10^ Btu) and setting the thermostat at 64°F provides a 5 per-
cent (6.4 x 106 Btu) savings. In the high baseline with the same modifica-
tion, burner maintenance saves an additional 8 percent (20.3 x 106 Btu) and
the lower indoor temperature saves 12 percent (31 x 106 Btu). Including all
measures (Modification F, burner maintenance and an indoor temperature of
64°F) as part of an energy conservation program on the high baseline leads to
a 77 percent reduction in energy use.
The annual cost (or payment) is computed using the formula which appears
in the footnote of Table 57.
104
-------
TABLE 57. ENERGY SAVINGS
(106 BTU/YR)
Modification
A
B
C
D
E
F
Low Baseline
Reduction Percent
(106 Btu/yr) Reduction*
High Baseline
Reduction Percent
(106 Btu/yr) Reduction**
6.5
7.5
22.6
12.9
35.5
63.4
5.5
6.3
19.1
10.9
30.0
53.6
29.6
29.6
32.7
57.6
90.3
160.4
11.1
11.1
12.3
21.6
33.9
60.2
*Low baseline: 118.3 x 106 Btu/yr
**High baseline: 266.4 x 106 Btu/yr
First Cost and Annual Cost (assuming 8 3/4 percent
interest rate & 25 year payment period)
Modification
A
B
C
D
E
F
Low Baseline
Total Cost Annual Cost***
($)
69
42
440
243
683
3,548
($)
6.9
4.2
44.0
24.3
68.3
354.8
High Baseline
Total Cost Annual Cost***
($) (?)
3,
70
265
440
400
880
970
7.0
26.5
44.0
40.0
88.0
397.0
***Annual cost figures are calculated using the expression
i
C = C_
a f
1-d+i)
-n
where:
C
= annual cost
C,. = total cost
i = interest rate (.0875 is used)
n = number of repayment periods in years (25 years is used)
105
-------
TABLE 58 . RELATIVE EFFECTIVENESS OF CONSERVATION MEASURES*
Low Baseline High Baseline
Modification ($/106 Btu) ($/106 Btu)
A 1.06
B .56
C 1.95
D 1.88
E 1.92
F 5.60
.24
.90
1.35
.69
.97
2.48
Relative Effectiveness is calculated by dividing the annual costs ($)
by the ai
values).
by the annual energy savings (10$ Btu) (see Table 57 for respective
106
-------
Cooling load reduction have been computed only for the high baseline
because we have not included energy for cooling in the low baseline. The
insulation modifications considered above (Table 56 ) are also used for cool-
ing. The energy savings which can be achieved with these modifications range
from 6 to 40 percent (See Table 59). Recall, however, that the total cooling
load in the baseline is only 8 percent of the energy requirement for heating.
Nonetheless, as much as 11.4 x 10 can be saved. Such a savings in cooling
in conjunction with a reduction in the space heating requirement can make even
the very high level of insulation (Modification F) extremely attractive to the
household. If, for this modification, the reduction in cooling load
(11.4 x 106 Btu/yr) is added to the reduction in heating requirement,
(160.4 x 10s Btu/yr), the relative effectiveness in dollars per unit of energy
saved is improved from $2.48/106 Btu to $2.31/106 Btu.
In Section 6 above, the reductions in heat loss and cooling load due to
placement of windows, effect of shade trees and other vegetation, mounding,
window awnings, drapes and Venetian blinds, and the color of walls and roof
have been listed. Although each can contribute to a decrease in energy
requirements they also serve other functions. Thus the portion of their costs
attributable to conservation cannot be assessed. Nonetheless in placing win-
dows, in landscaping, in interior decorating, and in selecting colors the
impact on demand for energy should not be ignored.
Solar Energy—
A solar energy system can provide a substantial portion of the heating
and cooling load of the house. However, because of the cost of such systems
we assume that the residence has already been insulated to conform with modi-
fication F above. In the low baseline with this modification the total heat-
ing load is 41.2 x 106 Btu/yr and in the case of the high baseline it is
68.9 x 106 Btu/yr.* In Section 6 Table 37 , data were presented showing that
in the northeast, solar energy systems can provide on the average between
75,000 Btu/yr-.and 120,000 Btu/yr for each square foot of collector panel
depending on the other components of the system. Costs vary from $6/106 Btu
to $11/106 Btu and the systems provide between 42 percent and 93 percent of
the annual household energy requirement for space and water heating.
The single family residences in the baselines have approximately 1,000
sq ft of roof area available for solar panels. Assuming that on the average
panels provided 100,000 Btu/sq ft per year, the roof area is sufficient to
meet a substantial portion of the space heating requirement. Although the
total output might be expected to be about 100 x 106 Btu/yr, in the winter
months some form of auxiliary heating system would be needed given that heat
loss would be greatest and insulation lowest. A conservative estimate might
The heating load is lower than the fuel requirement because the efficinecy
of the furnace is not included in the calculation. The fuel requirements
would be 59.9 x 106 Btu/yr. and 106.0 x 10€ Btu/yr.
107
-------
TABLE 59. COOLING LOAD REDUCTIONS
Low Baselines* High jjaselinef
D6 Btu 103kwh
yr. yr. Reduction
10 Btu 10 kwh Percent
Modification
A
B
C
D
E
F
2.9
1.7
2.3
5.4
7.7
11.4
.9
.5
.7
1.6
2.5
3.3
10.1
5.9
8.0
18.9
26.9
39.9
* There is no air conditioning in the low baseline.
t High baseline 28.6 x 105 Btu/yr (8.38 x 103 kwh/yr).
Parameters:
1) Incremental reduction in Btu/sq ft living space/cooling hour
from Table 34.
2) Living space: 1500 sq ft
Cooling hours: 400
Air conditioner efficiency: .65
108
-------
be that a solar system could provide for either baseline approximately half
of the heating requirement at a cost of $10/106 Btu. The remaining fuel
requirement would be 27.5 x 106 Btu/yr for the low baseline assuming a burner
efficiency of 75 percent, and 53.0 x 106 Btu/yr, for the high baseline assum-
ing an efficiency of 65 percent.
In the case of cooling (only the high baseline), the solar heating system
could be augmented with an absorption cooling machine such as a lithium
bromide absorption unit. Such a unit along with the necessary water cooling
tower and other hardware would cost between $2,000 and $4,000. If the unit
were added to the solar heating system, a conservative estimate would be that
reduces the cooling load by 50 percent from 28,6 x 106 Btu/yr to 14.3 x 106
Btu/yr. Assuming the unit costs $3,000 the implied cost/106 Btu would be $21.*
Even if the total cooling load could be accommodated by the system, the ratio
would still be over $10/106 Btu.
In Table 60 a summary of the conservation measures for modifications E
and F and solar panels is presented against the baseline cases. The impact of
increased burner efficiency and changing the thermostat settings is not
included. Cost estimates are shown.
Water Heating—
As in the case of space heating several modifications which can reduce
energy requirements are employed to illustrate the range of savings given the
baseline use. The effects of insulating hot water pipes, increasing storage
tank insulation and burner efficiency, the use of a flow through heater, and a
solar heater are considered. Also, the savings to be gained by lowering the
heater thermostat from 140°F to 120°F is shown. A description of all modifi-
cations and the estimates of their costs are presented in Table 61 . The
cost of a solar water heating unit does not appear in the table, since in most
cases the unit is part of the space heating system. In the discussion above
we assumed that the solar space heating system could provide energy at approxi-
mately $10/106 Btu.
Table 62 contains estimates of reductions in energy requirements for hot
water heating, based on the same approach as that used to develop the baselines
above. The table also contains a column of the ratio of annual cost to the
energy savings. As can be seen, few dramatic reductions in energy can be
expected in either baseline unless a flow through unit or a solar unit is sub-
stituted for the more conventional storage water heater. Nonetheless, the
cost-energy savings ratios show that given current fuel costs, all are reason-
ably attractive measures—particularly in the case of high energy use.
Lighting—
Of overriding importance in the conservation of energy for lighting is the
behavior of individuals in the home. Estimates of reduction in the baseline
are not made.
The $3,000 would translate into $300/yr assumed interest of 8.75 percent and
repayment period of 25 years. Thus $300/14.3 x 106 Btu = $21/106 Btu.
109
-------
TABLE 60. SUMMARY OF SELECTED CONSERVATION MEASURES FOR HEATING AND COOLING
Fuel
(106
Low Baseline
Remaining
Fuel
Reduction Requirement
Btu/yr) (106 Btu/yr)
Increment
Cost
(dollars)
Fuel
(106
High Baseline
Reduction
Btu/yr)
Remaining
Fuel
Requirement
(106 Btu/yr)
Increment
Cost
(dollars)
Baseline
Modification E
Modification F
H
M
° Solar Heating T
(plus Mod. F)
Solar Cooling 1"
(plus Mod. F)
Total
Heating
35.5
63.4
90.9
Heating
27.4 4,000
Heating Cooling Total Heating Cooling Total
118.3 - - 266.4 28.6 295.0
82.8 683 90.3 7.7 98.0 176.1 20.9 197.0 880
54.9 2,865 160.4 11.4 171.8 106.0 17.2 123.2 3090
7,548
213.4 11.4 224.8 53.0 17.2 70.2 4000
14.3 14.3 53.0 14.3 67.3 3000
- 10,970
* Cost of adding the modification or addition to all modifications made above.
t Solar Heating and Cooling assume insulation at level of modification F.
-------
TABLE 61. ENERGY CONSERVATION MODIFICATIONS FOR WATER HEATING
WITH COST ESTIMATES
Estimate of
Modification Measure Additional Cost*
A Insulate hot water pipes
(assume 100 ft.) $50 - $100
B New ASHRAE standards heater; $100
C Direct Conversion Heater with
electric ignition (80% effici-
ency) $200 1"
D Direct conversion heater with
electric ignition (80% effici-
ency) ; insulated pipes $250 - $300
E Solar water heater (assumed to
supply 50 percent of heat
requirement at 120°F) see discussion
Estimates of additional cost above that of standard storage unit in
residence with uninsulated hot water pipes.
This is a cost estimate obtained from Commonwealth Gas Company of
Massachusetts. The company estimates that a direct conversion unit costs
approximately $400 and a conventional storage unit $200. The additional
cost of the flow through unit is then $200.
Ill
-------
TABLE 62, WATER HEATING-ENERGY SAVINGS AND COSTS
Low Baseline
High Baseline
Baseline
Modification A
(insulate pipes)
Modification B
(ASHRAE heater)
Modification C
(Direct conversion
t- heater)
to
Modification D
(Mod. A plus Mod. c)
Modification E
(Solar heater)
Remaining Relative Remaining Relative
Reduction Requirement Effectiveness Reduction Requirement Effectiveness
(106 Btu/yr.) (106 Btu/yr.) ($/106 Btu) (106 Btu/vr) (106 Btu/yr) ($/106 Btu)
1.4*
1.6
3.8
5.8
12.3
24.5
23.1
22.9
20.7
18.7
12.2
3.6-6.2
6.3
5.3
4.3-5.2
lot
2.0*
2.3
7.2
9.2
17.9
35.8
33.8
33.5
30.3
28.3
17.9
2.5-5.0
4.4
2.8
2.7-3.3
lot
Based on an estimate of reduction in hot water use from Bulletin No. 198, California Department of
Water Resources (38).
t Taken from discussion of space heating.
-------
Kitchen—
Total energy use in the kitchen for the low baseline is assumed to be
7.0 x 10^ Btu/yr. We consider only a few individual measures for energy sav-
ings since reductions are not very dramatic and cost estimates are question-
able. Table 63 describes the measures and provides estimates of energy savings
and costs. Although none of the measures provide very great reductions in
energy use (with the possible exception of the elimination of gas pilot), in
combination a reduction of over 50 percent can be achieved in the low baseline
and almost 40 percent in the high baseline.
Washing and Cleaning—
Under this function the primary use of energy comes from the clothes dryer.
In the low baseline 5.0 x 106 Btu/yr was allocated to the dryer, and in the high
baseline 7.5 x 106 Btu/yr was allocated. The remainder, in each case, is used by
the washing machine and miscellaneous cleaning devices. In Section 6 we have
pointed out that the gasket seals on the dryer door should be kept in good
repair and that the heat loss could be reduced by increasing insulation,
but estimates of energy savings have not been made. However, even a 50
percent reduction in energy use only eliminates 2.3 x 106 Btu/yr from the
overall household demand for the low baseline and 3.8 x 106 Btu/yr from the
high baseline.
Bathroom—
Energy conservation is not considered under this function.
Living and Entertainment—
The important uses of energy are the color television with the "instant-
on" feature (high baseline) which uses about 525 kwh/yr (approximately
1.8 x 105 Btu/yr) and radio/stereo which uses 150 kwh/yr (approximately
.5 x 106 Btu/yr). Elimination of the "instant-on" can reduce the television
energy use by 50 percent. Other reductions are negligible.
Outdoors and Maintenance—
Energy conservation was not considered under these functions.
Summary of Energy Conservation—
To show the combined effect of the energy conservation measures on the
baselines, modified baselines which incorporate a number of the conservation
measures have been computed. In all cases those measures which lead to the
greatest energy savings are included. Thus in the case of space heating the
modified use figures are for residences with the highest levels of insulation
plus solar heating systems. For water heating, the energy use figures are for
a solar heater with auxiliary direct conversion flow-through heaters. Also,
for each function total costs of the modifications are computed. The new
energy use and cost figures appear in Table 64 .
In the modified low baseline the total energy requirement is approximately
one-third of the original baseline. The estimate of the total cost is
slightly more than $9,000. For the high baseline the modified energy
requirement is 30 percent of the unmodified baseline. The total cost estimate
is $13,350.
113
-------
TABLE 63. ENERGY CONSERVATION MEASURES IN THE KITCHEN
Low Baseline High Baseline
Reduction Reduction
Cost (106 Btu/yr) (106 Btu/yr)
Modification
A Install on/off switches
on anticondensation $20* N/A
heaters in refrigerator
and freezer
B Gas range with electric
ignition and improved $50 2.8
insulation'
C Increased insulation in
refrigerator and freezer $200 .9
D Do not use dryer cycle _
in dishwasher N/A
1.0
3.0
1.9
.4
Total
Reduction
3.7
6.3
* Assume materials cost $5 and labor $15.
t Assume substitution of electric ignition for pilot reduces energy use by
2.2 x 106 Btu/year and that improved insulation reduces loss by another
.6 x 106 Btu/year in the low baseline and .8 x 106 Btu in the high base-
line.
114
-------
TABLE 64. MODIFIED ENERGY BASELINES
Space Heating
Cooling
Water Heating *
Lighting
Kitchen
- Range
- Dishwasher
- Refrigerator
- Freezer
- Miscellaneous
Washing/Cleaning
- Washing machines
- Dryer
- Miscellaneous
Bathroom
- Miscellaneous
Living/Entertainment
- Television
- Radio/Stereo
- Miscellaneous
(hobbies)
TOTAL
Modified
Low Use
Million Portion Total
Btu/vr of Total Cost ($)
27.4 .53 7,548
_
12.2 .23 1,530
1.7 .03
4.3 .08 150
[1.2] [50]
[1.6] [100]
[1.5]
5.6 .11
[0.3]
[5.0]
[0.3]
0.1
0.9 .02
[0.3]
[0.3]
[0.3]
52.2 1.00 9,228
Modified
High Use
Million Portion
Btu/yr of Total
53.0 .47
14.3 .13
17.9 .16
6.0 .05
10.6 .10
[1.8]
[ .8]
[3.0]
[3.5]
[1.5]
8.3 .07
[0.5]
[7.5]
[0.3]
-
1.7 .02
[0.9]
[0.5]
[0.3]
111.9 1.00
Total
Cost ($)
7,970
3,000
2,090
-
290
[50]
[120]
[120]
-
-
-
13,350
This assumes in the low baseline solar system costing approximately $1230
(based on a cost of $10/106 Btu/yr supply 12.3 x 106 Btu). If annual pay-
ment is the $123 using 8.75 percent interest and 25 yrs the total cost is
$1230. Assume also $300 for auxiliary flow-through heater (over cost of
conventional pipes). In the high baseline it is assumed that the total cost
of the solar system plus auxiliary system is $1790 + $300 = $2090.
115
-------
Gaseous Residuals
Given that we have assumed gaseous residuals generation to be proportional
to energy use for those functions which burn fuel on the premises,the deter-
mination of gaseous residuals reductions is merely a matter of multiplying
the ratios in Table A-5 by the energy reductions (converted to cubic feet of
natural gas). Because the task of computing reductions is straightforward we
present only one example using the energy figures in the modified baselines
(Table 64 ). The results are contained in Table 65. Comparing them with the
original baselines shows that reductions of almost 80 percent can be achieved.
Water Use and Liquid Residuals
In water conservation the functions of space heating and cooling, light-
ing, and living and entertainment are not considered.
Water Heating—
Insulating the hot water lines can reduce water use by somewhere between
one and four percent at a cost of $.50 to $1.00 per foot of line (41). In
the low baseline the savings of water would be between 660 gallons and 2,660
gallons per year and in the high baseline between 1,100 gallons and 4,500
gallons per year. If 100 feet of pipe are insulated at $1.00 per foot and if
that resulted in a savings, of one percent of the indoor water use the cost/
1000 gallons saved would be $.02 in the low baseline and less than $.01 in
the high baseline.*
Kitchen—
As has been shown above, few water saving devices exist for the kitchen.
Flow aerators may reduce the consumption of water used for washing of foods,
hands, and miscellaneous dishes, but there is opinion on using them differ-
ently. In the high baseline, we assume that the garbage grinder and the
dishwasher are each used twice daily. If the dishwasher is used once a day
and the garbage grinder is eliminated the kitchen water use can be reduced
by 10,220 gallons/yr (a reduction of 40 percent of the kitchen use). Also,
the hydraulic waste load is reduced and the major source of organic wastes is
removed. Table 66 contains a summary.
The costs associated with these reductions are really a matter of con-
venience to the household as well as a matter of transforming-the organic
liquid residual into organic solid residual. In fact, not installing a gar-
bage grinder can save between $100 and $250.
Washing and Cleaning—
Principal savings can be achieved by installing a washing machine with a
water level selector and by using a "suds saver." A selector can reduce use
by about 10 percent. In the low baseline 820 gallons/yr and in the high
Assume that the pipe insulation cost is included in cost of structure
and paid off in same fashion (i.e., at 8.75 percent interest over a period
of 25 years).
116
-------
TABLE 65.
GASEOUS RESIDUALS OF MODIFIED LOW AND HIGH BASELINES
(LBS/YR)
Particulate
S02 SO3
Hydro-
CO carbons N02
Space Heating
Water Heating
Range
Total
(Low Baseline)
Total
(High Baseline)
0.3
0.1
—
0.4
0.7
0.5
0.2
— - —
0.7
1.4
0.2
0.1
—
0.3
0.6
2.1
0.9
0.1
3.1
5.7
TABLE 66. WATER AND WASTEWATER REDUCTIONS IN THE KITCHEN
(High Baseline)
Measure
eliminate
garbage grinder
use dishwasher
once/day
Total
Water Saved
(gal/yr)
4,380
5,840
10,220
Waste Load Reduction (Ib/yr)
BOD SS TN TP
116.8 131.4 1.5 1.5
1.5
116.8 131.4 1.5 3.0
Reduction as
Percent of Kitchen
functions
40
70 90 33 50
117
-------
baseline 1,640 gallons/yr would be saved. The "suds saver" reduces washing
water volume between 20 and 30 percent depending on the number of times the
wash water is reused. The annual savings, assuming one reuse, would be
approximately 1,640 gallons for the low baseline and 3,285 gallons for the
high baseline. The selector can make a washing machine slightly more expen-
sive — perhaps $20 to $30. The cost of a "suds saver" is in the same range.
Also, use of a "suds saver" would reduce slightly the organic residuals.
Since detergenets are an important source of BOD and phosphates, reuse of
the wash water probably can lower the washing and cleaning components of these
residuals by about 25 percent. The effects are summarized in Table 67.
Bathroom—
The greatest water savings can be realized within the bathroom function.
Several combinations of water saving devices and estimates of their additional
costs (i.e., cost incremented above conventional devices) are presented in
Table 68. They range from modest changes such as dual flush mechanisms on
toilets and low flow shower heads (Modification A in the table) to composting
toilets and gray water recycling systems (Modification E in the table).
In Table 69 are found the reductions in the baselines which might be
anticipated if the bathroom were equipped with these water saving features.
Note that some equipment is used only in the high baseline. The more reliable
estimates of the decreased water use are those for the toilet, since a
decrease in the volume of water necessary to flush a toilet is translated
directly into savings. The estimates of both shower and sink water saved are
less reliable. A reduced flow rate does not necessarily translate into
savings. For a bath it is unimportant and for shower and sink use it may
have only a marginal effect on total water used. Nonetheless as the figures
in the table demonstrate, remarkable reductions in water use can be achieved,
some even with small investments in hardware which use water more efficiently.
For the low baseline the Modification A leads to slightly more than a 20
percent (9,490 gal/yr) reduction in water used in the bathroom and both Modi-
fication C_and E lead to about a 55 percent (21,900 gal/yr) reduction. The
other modifications lead to savings between these extremes. The cost/1,000
gallons of water saved (assuming the same interest rate and pay off schedule
used above) ranges from .22 for Modification A to 10.8 for Modification E.*
In the case of the high baseline, savings are lowest for Modification A
(33 percent) and highest for Modification E (92 percent). Calculating
cost/1, 000 gallons of water saved for the high baseline depends on the assump-
tion made about necessity of duplicating equipment given that the residence
has two bathrooms. We will assume that pressure tanks and gray water recy-
cling plumbing need not be duplicated and that only one composting toilet is
installed. We also assume that these items reflect almost all of the cost of
the mechanisms. Given these assumptions and those made above about interest
* In the low baseline the costs of any shower modification are excluded
because it is assumed that the bathroom has only a tub.
118
-------
TABLE 67 - WATER CONSERVATION MEASURES IN WASHING AND
CLEANING
Low Baseline
Water Saved*
(gallon/yr.)
Reduction in Liquid Residuals (Ib/yr.)
SS TN TP
Water level
selector on
machine
"Suds Saver"
820
1,640
4.5
.9
.2
.1
Water Saved*
(gallon/yr.}
High Baseline
Reduction in Liquid Residuals (Ib/yr.)
BOD5 SS TN TP
Water level
selector on
machine
"Suds Saver"
1,640
3,285
9.3
1.9
.4
.1
The amounts of water saved with the water level selector and the "Suds
Saver" are not strictly additive since the "Suds Saver" estimate is
based on a full work load.
119
-------
TABLE 68- WATER CONSERVATION MEASURES IN THE BATHROOM
Modification Description Cost
A -dual flush $ 16
- shower head flow control 20
- sink nozzle aerator 5
$ 41
B -pressurized tank toilet $ 40
-pressure balancing 40
-sink nozzle aerator 5
$ 85
-shallow trap toilet
-gray water recycling sys-
tem from bath, shower,
and sink to toilet $360
§360
-pressurized flush toilet $260
-air-assisted shower head 275
$535
-composting toilet (Clivus
Multrum) $2,000
-air-assisted shower head 275
-gray water recycle to irri-
gate lawn 360
$2,635
120
-------
TABLE 69- EFFECTS OF WATER SAVING DEVICES ON BATHROOM WATER USE
Low Baseline
Reduction (gal/yr) due to:
Modification A Modification B Modification C Modification D Modification E
Toilet
Bath*
Sink
Total
Reduction
7,300
2,190
9,490
12,650
2,190
14,840
21,900
21,900
19,160
19,160
21,900
21,900
* Given the specification in the low baseline that the bathroom is equipped with a tub, but
not with a shower, a reduction in water use is not attributed to low flow shower heads or
pressure balancing valves.
High Baseline
Reduction (gal/yr) due to :
Modification A Modifciation B Modification C Modification D Modification E
Toilet
Bath
Sink
Total
Reduction
9,730
10,950
2,190
22,870
25,310
8,760
2,190
36,260
43,800
43,800
40,150
20,750
60,900
43,800
20,750
64,550
-------
rates and the payment schedule the cost/1,000 gallons saved is .36 for Modifi-
cation A and 4.1 for Modification £. The others are within this range.
The reduction in wastewater hydraulic load is the water saved. However,
the only measure which will have more than a marginal effect on the organic
residuals is Modification E. In that case all the organics from the toilet
and the kitchen are composted and the gray water residuals are put on the
land.
Outdoors—
In the high baseline outdoor water use amounts to 29,200 gallons/yr given an
irrigation water requirement of .25 inches/week during the spring and summer.
No overwatering is assumed. Thus, no attempt is made to relate the use of
sprinkler devices or soil moisture measurement devices to water savings. But
the effect of a gray water recycling system which provides lawn irrigation
water can be estimated. During the spring and summer 1,325 gallons/week are
needed. If all the bathroom gray water is used approximately 500 gallons/week
are available which would provide 40 percent of the requirement. Above in Sec-
tion 6 we have assumed the total cost of such a system to be about $360.
We have not made estimates of the impact of landscaping with vegetation on
water requirements or runoff, nor have we attempted to determine the conse-
quences of efforts to reduce stormwater runoff.
Maintenance—
A spring type nozzle might be assumed to reduce water use in car washing
by 50 percent from the equivalent of 10 gallons/day to 5 gallons/day. The
cost would be marginal. Baseline data on the pollution problem of discarded
lubricating oil do not exist.
Summary of Hater Savings and Liquid Residuals Reduction—
Because of their interdependences, conservation measures designed to save
water and reduce liquid residuals do not lend themselves to the type of sum-
mary used above with energy conservation. However there are few points which
might be reen^Jhasized. First, the greatest savings in water can be achieved
by introducing conservation measures in the bathroom—particularly by modi-
fication of the toilet. Second a substantial reduction in liquid residuals
can be realized by eliminating garbage grinders which are the greatest single
source of organics in our high baseline. Last, other large reductions in
water use or liquid residuals generation depend on introducing those systems
which have their own energy requirements (e.g., pressurized flush toilets and
air-arrested showers) or systems which have not yet been accepted by large
portions of the population (e.g., composting toilets).
Solid Residuals
Solid residuals can be reduced by the various measures discussed in Sec-
tion 6. How some of these measures can be applied to the reduction of the
low and high baselines of solid residuals generation is delineated below.
Because the reduction in solid residuals depends so much on actions taken by
members of the household we have selected a stepwise approach to illustrating
options for reducing the residuals. The steps are segmented and each one
implies an additional measure taken to lower the generation of residuals.
122
-------
Some options are already implied in the low- baseline since it was not defined
primarily on the basis of fewer "potential solid residuals" (i.e., reduced
material input to household) but rather on the assumption that the house-
hold already was taking some measures to reduce solid residuals. The low
baseline is presented first.
Low baseline—
Table 70 contains measures which result in a reduction of the low base-
line figures. The following reductions are derived from these measures
(summarized in Table 71).
Step 1—Conscious participation in separation programs leads to weekly
separation at a rate of 80 percent of newspaper and 80 percent of the maximum
recycling rate of 60 percent of the total glass and metals component; this
results in an incremental reduction of 73 kg/yr for newspaper and 59 kg/yr
for glass and 44 kg/yr for metals; the inconvenience is assessed with B.
Step 2—Separation of materials not centrally collected and voluntary
transport to satellite recycling centers could perhaps decrease the rate of
generation of the "miscellaneous" component (for example, plastics) by 10-
20 percent and the original paper component by 5-10 percent (brown paper bag
and other cardboard materials); due to voluntary participation, the lower
limits have to be assumed. This results in an incremental reduction of
15 kg/yr (miscellaneous) and 29 kg/yr (paper), respectively, at an incon-
venience level of D.
Step 3—A source separation ordinance should make the source separation
program slightly more effective; an increase to the 90 percent of the news-
paper component and 90 percent to the maximum recyclable fraction of glass
and metals (which was 60 percent of the total glass and metal components),
results in an incremental reduction of 29 kg/yr (newspaper), and 15 kg/yr
for glass and 7 kg/yr for metals, respectively, at an inconvenience level
of B.
Step 4—Establishment of a compost heap would affect about 50 percent
of the organics and possibly 80 percent of the garden waste; this yields a
reduction of 277 kg/yr for organics and 263 kg/yr for garden wastes at an
inconvenience rate of B.
Step 5—The enactment of a bottle bill would reduce presumably the metal
and glass components of the total metal and glass residuals (baseline) by
20 and 35 percent, respectively; given that the remaining glass and metal
residuals are separated and recovered at the rate assumed in Step 3, the
incremental reduction is 29 kg/yr for glass and insignificantly small for
metals at an inconvience of B.
Step 6—Very conscious efforts of the household to purchase only products
with small packaging amount might reduce the original paper component by
about 2-3 percent at an inconvenience level of D; the rate is so small because
the household had avoided buying precooked food which is quite intensive in
paper; incremental reduction might be 15 kg/day at an inconvenience D.
123
-------
TABLE 70. REDUCTION OF SOLID RESIDUALS GENERATION
(Low Baseline)
II
III
Step 1:
Step 2:
satellite recycling cen-
ter accepting materials
separately collected
conscious participation
in separation program
separation of all
materials
take materials that are
not centrally collected
voluntarily to recycling
center
Step 3:
source separation ordin-
ance; scavenger ordinance
conscious fulfillment of
source separation ordin-
ance
Step 4:
city encouragement for use
of compost heaps in gar-
dens (organizational
instructions)
set a place aside for a
compost heap
Step 5:
enactment of
Step 6:
"bottle bill"
put organics (including
garden waste, but
excluding bones from
meals) on compost heap
return containers covered
under bottle bill
conscious effort of buy-
ing products with small
amount of packaging
material
I = administrative/institutional
II = physical/technological
III = behavioral
124
-------
Baseline
TABLE 71 . REDUCTION OF LOW BASELINE SOLID RESIDUALS
(kg/yr)
Organics Paper Glass Metals Misc. Garden Total
540 394 204 102 175 336 1,752
Step 1:
Reduction
Remainder
Step 2:
Reduction
Remainder
Step 3:
Reduction
Remainder
Step 4:
Reduction
Remainder
Step 5:
Reduction
Remainder
Step 6:
Reduction
Remainder
-
540
-
540
-
540
277
263
-
263
-
263
73
321
29
292
29
263
263
-
263
15
248
59
145
-
145
15
130
-
130
29
101
-
101
44
58
-
58
7
51
-
51
-
51
-
51
-
175
15
160
-
160
-
160
-
160
-
160
-
336
-
336
-
336
263
73
-
73
-
73
1,576
1,532
1,481
941
912
897
125
-------
High baseline—
Table 72 contains measures which could reduce the solid residuals
generation in a stepwise, accumulative way. The following reductions are
derived from these measures (summarized in Table 73}.
Step 1—For the reduction of paper component assume that 80 percent of
the total newspaper component is separated for newspaper collection, this
yields an increase of 117 kg/yr in separated newspaper; the inconvenience
is assessed with B.
Step 2—Materials, such as glass and metals, are separated in addition to
newspapers, and voluntary transport to neighborhood recycling center; assuming
that 25 percent of the glass component and 30 percent of the metal component
is recycled, the reduction is 102 kg/yr for glass and 58 kg/yr for metals at
an inconvenience of D.
Step 3—All materials that have to be separated according to ordinance
(newspaper, glass, metals) are regularly collected; assuming an increase of
the reduction of the newspaper component to 90 percent and of the maximal
recyclable glass and metal fraction (with is thought to be 60 percent of the
total glass and metal component) to 90 percent yields an incremental reduction
of 15 kg/yr for newspaper, 146 kg/yr for glass, and 73 kg/yr for metals at
an inconvenience level of B.
Step 4—Establishment of a compost heap would affect about 50 percent of
the organics (computed only from the amount that is ground up in the garbage
grinder) and possibly 80 percent of the garden waste; this yields a reduction
of 263 kg/yr at an inconvenience rate of B; by reducing the amount of pre-
cooked food purchased, the original paper component is reduced by 3 percent
(15 kg/yr) at an inconvenience of C.
Step 5—The enactment of a bottle bill would reduce presumably the total
metal and glass components of the residuals (baseline) by 20 and 35 percent
respectively; given that the remaining glass and metal residuals are recovered
at the rate assumed in Step 3, the incremental reduction is 15 kg/yr for
metals and 44 kg/yr for glass at an inconvenience rate of B.
Step 6—Very conscious efforts of the household to purchase only products
with small packaging amount might reduce the original paper component by about
5 percent at an inconvenience level of D.
126
-------
TABLE 72
REDUCTION OF SOLID RESIDUALS GENERATION (High Baseline)
II
III
Step 1:
increase reliability
of separate collection
of newspaper
increase frequency of
collection to (I/week) at
days of regular collection
conscious participation
in separation program
Step 2;
Recycling center
for citywide opera-
tion with satellite
centers (paper, glass,
metals)
bins for separating
materials
separation of all
materials
take materials that are
not centrally collected
voluntarily to recycling
center
Step 3;
regular collection of
all separated materials
source separation
ordinance
scavenger ordinance
conscious fulfillment
of source separation
ordinance
Step 4:
city encouragement for use set a place aside for
of compost heaps in gardens compost heap
(organizational instructions)
127
put organics (including
garden waste, but perhaps
excluding bones from meals)
on compost heap (instead
of grinding them up)
-------
TABLE 72 (continued)
II
III
Step 4 (continued)
reduce amount of pre-
cooked and package food;
buy fresh food whose
residuals can be
composted
Step 5;
enactment of "bottle bill1
return containers
covered under bottle
bill
Step 6;
conscious efforts of
buying products with
small amount of packaging
materials
128
-------
Baseline
TABLE 73. REDUCTION OF HIGH BASELINE SOLID RESIDUALS
Ocg/yr)
Ofganics Paper Glass Metals Misc.
29 511 423 204 292
Garden Total
336 1,795
Step 1:
Reduction
Remainder
Step 2:
Reduction
Remainder
Step 3:
Reduction
Remainder
Step 4:
Reduction
Remainder
Step 5:
Reduction
Remainder
Step 6:
Reduction
Remainder
117
29 394
29 394
15
29 379
15
29 362
29 362
29
29 333
423
102
321
146
175
175
44
131
131
204
58
146
73
73
73
15
58
58
292 336 1,678
292 336 1,518
292 336 1,284
263
292 73 1,004
292 73 945
292 73 916
129
-------
Summary—
The reduction of the total load of solid residuals was close to 50%
in both baselines even though the reduction of each individual component
was quite different. The low baseline was largely decreased due to composting
of organics and garden waste. The decrease of the high baseline was made
possible by composting garden wastes and separating paper, glass and metal
fractions, because the garbage grinder was used to dispose of all those
organics which should not be put on a residential compost heap. Thus,
given residential property with gardens, composting garden waste is the
single most important reduction in the presence of garbage grinders; while
in its absence composting organics together with garden wastes make up
the single largest reduction. If additional paper fractions would be
separated at the same scale as newspaper, reduction of the paper component
would cause another major decrease of the total load.
130
-------
REFERENCES
1. Bower, B.T., Ehler, C.N., and Kneese, A.V., "Implementation Incentives
for Environmental Quality Management," Environmental Science and Tech-
nology , Volume 11, March 1977.
2. Bower, B.T., "Studies of Residuals Management in Industry," in E.S.
Mills (ed.), Economic Analysis of Environmental Problems, Columbia Univer-
sity, 1975.
3. MacAvoy, P.W., "Comment on 'Bower, B.T., Studies of Residuals Management
in Industry1," in E.S. Mill (ed.), Economic Analysis of Environmental
Problems, Columbia University Press, 1975.
4. Carroll, T. Owen, et al., Land Use and Energy Utilization (Interim Report),
for Office of Conservation and Environment, Federal Energy Administration,
February 1976, p. 55.
5. American Society of Heating, Refrigeration and Air Conditioning Engineers,
Inc., ASHRAE - 1973 Systems Handbook.
6. U.S. Environmental Protection Agency (EPA), "Compilation of Air Pollu-
tant Emission Factors," Second Edition, April 1973, AP-42; U.S. EPA,
Supplements #1, 2, and 3 to the above.
7. Committee on Finance, U.S. Senate, Energy Statistics, Washington, D.C.:
U.S. Government Printing Office, July 1975.
8. American Gas Association, 1974 Gas Facts, Arlington, Virginia, 1975.
9. Edison Electric Institute, "Annual Energy Requirements of Electric House-
hold Appliances," New York, N.Y., 1975.
10. Boston Edison, "The Wise Use of Energy," Boston, Massachusetts, undated.
11. Hittman Associates, "Residential Energy Consumption," Phase I Report,
prepared for Department of Housing and Urban Development, March 1972.
12. Hittman Associates, "Multifamily Housing Final Report," prepared for U.S.
Department of Housing and Urban Development, Washington, D.C.: Govern-
ment Printing Office, June 1974.
*
13. American Society of Heating, Refrigeration and Air Conditioning Engineers
(ASHRAE), Inc., "Energy Conservation in New Building Design," ASHRAE
Standard No. 90-75, 1975.
131
-------
14. "Project Independence," Federal Energy Administration Project Independence
Blueprint Final Task Force Report, Volume 1, prepared by the Interagency
Task Force on Energy Conservation, under direction of Council on Environ-
mental Quality, November 1974.
15. Consumer Report, December 1975, pp. 7-8.
16. "Patterns of Energy Consumption in the U.S.," Stanford Research Insti-
tute, January 1972.
17. Bennett, E.R., K.D. Linstedt and J. Felton, "Comparison of Septic Tank
and Aerobic Treatment Units: The Impact of Wastewater Variations on
These Units," Proceedings of the Rural Environmental Engineering Confer-
ence, University of Vermont, Burlington, Vermont, 1975.
18. Ligman, K., N. Hutzler, and W.C. Boyle, "Household Wastewater Charac-
terization," Journal of Environmental Engineering Division ASCE, 100, EEL,
February 1974, pp. 201-215.
19. Witt, M.D., "Water Use in Rural Homes," Small Scale Waste Management Publi-
cation, 1974, 27 pp.
20. Association of Home Appliance Manufacturers, "Energy Data," Chicago,
Illinois, undated.
21. Citizen's Advisory Committee on Environmental Quality, "Citizen Action
Guide to Energy Conservation," 1973.
22. Siegrist, R., M. Witt, and W.C. Boyle, "Characteristics of Rural House-
hold Wastewater," Journal of Environmental Engineering Division ASCE, 102
June 1976, pp. 533-548.
23. Bennett, E.R. and K. Linstedt, "Individual Home Wastewater Characterization
and Treatment," Environmental Resources Center Completion Report Series
no. 66, Colorado State University, Fort Collins, Colorado, July 1975.
24. Cohen, S. and H. Wallman, "Demonstration of Waste Flow Reduction for
Households," prepared for U.S. EPA, September 1974, DPA-670/2-74-071.
25. Census of Housing, 1970, Bureau of Census, Department of Commerce,
Washington, D.C.
26. Environment Information Center, Inc., The Energy Index, Volume 3, New
York, N.Y., December 1975.
27. Merchandising Week 102, (8), 1970.
28. Center for Environmental Studies, Princeton University, "Energy Conser-
vation in Housing," continuation proposal submitted to the National
Science Foundation, 1975.
132
-------
29. Bailey, J.R., R.J. Benoif, J.L, Dodson, J,M, Robb and H. Wallman, "A
Study of Flow Reduction and Treatment of Wastewater from Households,"
U.S. EPA, 11050FKE 12/69, December 1969.
30. Haney, P.D. and C.L. Hamann, "Dual Water Systems," Journal American
Water Works Association, 57, September 1965.
31. Laak, R., "Home Plumbing Fixture Waste Flows and Pollutants," Unpublished
Report, University of Connecticut, Storrs, Connecticut, 1972.
32. Ligman, K., "Rural Wastewater Simulation," M.S. Independent Study
Report, University of Wisconsin, Madison, Wisconsin, 1972.
33. Wallman, H., " Should We Recycle/Conserve Household Water?" 6th Inter-
national Water Quality Symposium, Washington, D.C., April 18-19, 1972.
34. Reid, G.W., "Projection of Future Municipal Water Requirements," South-
west Water Works, S. 46;18, 1965.
35. Witt, M., R. Siegrist, and W.C. Boyle, "Rural Household Waste-Water
Characterization," Proceedings of the National Home Sewage Disposal
Symposium, December 1974, pp. 79-88.
36. "Public Water Supplies in the 100 Largest Cities in the United States,"
U.S. Geological Survey, Water Supply Paper No. 1812, 1962.
37. Laak, R., "The Effect of Aerobic and Anaerobic Household Sewage Pre-
treatment of Sewage Beds," Ph.D. thesis presented at the University of
Toronto, Toronto, Ontario, Canada, 1966.
38. Water Conservation in California, Department of Water Resources, Bulletin
No. 198, May 1976.
39. Howe, W. and F.P. Linaweaver, Jr., "The Impact of Price on Residential
Water Demand and its Relation to System Design and Price Structure,"
Water Resources Research, Volume 3, No. 1, 1967.
40. Linaweaver, F.P., et al., Report V on Phase Two of the Residential Water
Use Project, Department of Environmental Engineering Science, Johns Hop-
kins University, 1966.
41. Milne, M., Residential Water Conservation, California Water Resources
Center Report No. 35, March 1976.
42. Andrews, Richard A. and Martha R. Hammond, Characteristics of Household
Water Consumption in Three New Hampshire Communities, Water Resources
Research Center, University of New Hampshire, December 1970.
43. Niessen, W.R. and S.H. Chansky, "The Nature of Refuse," Proceedings of
1970 National Incinerator Conference, ASME Incinerator Division, Cincin-
nati, Ohio, May 17-20, 1970, p. 4.
133
-------
44. Comprehensive Studies of Solid Waste Management - First and Second
Reports, HEW, Public Health Service Publication No. 2039, p. 20.
45. Darnay, A. and W.E. Franklin, Salvage Markets for Materials in Solid
Wastes, for EPA, Contract No. CPE 69-3, 1972, p. 156-2.
46. Meier, P.M. , J. KUhner, and R.E. Bolton, Wet jysteins for Residential
Refuse Collection; A Case Study of Springfield, Massachusetts, Report
by Curran Associates, Inc. to EPA Solid and Hazardous Waste Research
Laboratory, Cincinnati, Ohio, March 1974 (published by NTIS, PB-234-
499/AS).
47. Sartor, J.D. and G.B. Boyd, "Water Pollution Aspects of Street Surface
Contaminants," U.S. EPA, EPA-R2-72-081, November 1972.
48. Sutherland, R. and R. McCuen, "A Mathematical Model for Estimating Pol-
lution Loadings in Runoff from Urban Streets," Chapter 7 in "Flood Run-
off from Urban Areas," by R. McCuen, University of Maryland Water
Resources Center, 1975.
49. American Public Works Association, "Nationwide Characterization, Impacts
and Critical Evaluation of Stormwater Discharges, Non-Sewered Urban
Runoff and Combined Sewered Overflows," Progress Report to U.S. EPA,
August 1974.
50. Young, G.K., "NPS Impact and Urban Holding Capacity: Major Issues,"
Proceedings, Urban Stormwater Management Seminars, Water Quality Manage-
ment Guidance Document WPD 03-76-04, pp. 1/98 - 122, U.S. EPA, January
1976.
51. Meta Systems Inc, "New Residential Development and the Quantity and
Quality of Runoff," Proposal submitted to U.S. EPA, 10 December 1976.
52. Development Document for Proposed Effluent Limitations Guidelines and
New Source Performance Standards to the Auto and Other Laundries,
EPA Office of Enforcement and General Council, April 1974.
53. Decision Makers Guide in Solid Waste Management, EPA Office of Solid
Waste Management Programs, SW-500, 1976.
54. Maugh, Thomas H., II, "Rerefined Oil: An Option that Saves Oil, Mini-
mizes Pollution," Science, Volume 193, 17 September 1976.
55. Brochure "Custom Heat Recovery Systems: Industrial, Commercial, Residen-
tial," Maxi-Heat Recovery Systems, Inc., Milton, Massachusetts, 1977.
56. Massdesign, Solar Heated Houses, for New England and Other Temperate
Climates, Third Edition, July 1975, pp. 7 and 43.
57. Ward, Dan S., et al., Performance of a Residential Solar Heating and
Cooling System, Colorado State University, June 1975.
134
-------
58. Arthur D. Little, Inc., "An Impact Assessment of ASHRAE Standard
90-75, Energy Conservation in New Building Design," December 1975,
pp. 35 and 71.
59. Hill, James E. and Thomas E. Richtmyer, "Retrofitting a Residence for
Solar Heating and Cooling: The Design and Construction of the System,"
NBS Technical Note 892, National Bureau of Standards, Washington, D.C.,
November 1975.
60. Personal Communication with R.D. Johnston, Commonwealth Gas Company of
Massachusetts, February 1977.
61. Personal Communication, February 1977.
62. Personal Communication with Boston Stove Company, March 1977.
63. SCS-Engineers, "Analysis of Source Separation Collection of Recyclable
Solid Waste," EPA-publication SW-95C.1, 1974; NTIS-PB-239775.
64. National Analysts,"Metropolitan Housewives' Attitudes toward Solid Waste
Disposal," Report Prepared for U.S. Environmental Protection Agency,
EPA-R5-72-003, 1972.
65. Resource Planning Associates, Inc., "Source Separation-The Community
Awareness Program in Somerville and Marblehead, Massachusetts," Report
Prepared U.S. Environmental Protection Agency, EPA/530/SW-551, November
1976.
66. Newspaper clippings over the last 12 months relating to bottle bill and
source separation programs in the Boston area.
67. Lager, J. and G. Smith, "Urban Stormwater Management and Technology: An
Assessment," Metcalf & Eddy, Inc., for U.S. EPA, December 1974.
68. Irwin, W.A., "Alternative Institutional Approaches to Recycling Used Oil,"
Paper #12 of the Symposium on the International and Comparative Dimensions
of Water Recycling and Reuse, Bellagio, Italy, 12-17 November 1976.
135
-------
APPENDIX A
HOUSEHOLD FUNCTION: DETAILED PRESENTATION
INTRODUCTION
Each of the household functions (see Table A-l) is discussed in this
appendix. Included are mass and energy flow charts of the respective func-
tions ,* accompanied by a discussion and summary of available data on water
use, energy use, liquid residuals generation (including 5-day biochemcial
oxygen demand, suspended solids, total nitrogen and total phosphorus), gas-
eous residuals generation (including particulates, hydrocarbons, sulfur
oxides, nitrogen oxides, and carbon monoxide) and available data on costs of
conservation and modification alternatives. Discussion of solid residuals
generation is concentrated within the Kitchen function.
The extent of coverage differs between the sections and within each sec-
tion among the different categories of activities and flows. These differ-
ences reflect primarily our judgments as to the relative importance of each
function and category within the household and the number of available alter-
natives .
SPACE HEATING AND COOLING
Space heating and cooling is the household function which uses the
greatest amount of energy. In a typical single-family home in the northeast
with 5500 heating degree days and 400 cooling hours, over 65 percent of the
household energy used will be devoted to this function { 1 ). The space
heating/cooling flow charts (Figures A.I and A.2) show the flow of energy
through each of the functions and illustrate the points at which residuals
are generated.
The discussion of these functions proceeds backwards in this appendix
for each of the charts (i.e., from structure to HVAC (Heating, Ventilating
and Air-Conditioning) system to fuel to residuals generated). This is done
for two reasons, the first being that it is our intent to give users of this
report an idea of the heating/cooling load for various kinds of structures
and so it is logical to begin with the design of the structure. The second is
that our ultimate objective is the identification of measures for energy con-
servation in new buildings and the best place to start is the structure itself.
Mass and energy flow charts are not included for the Maintenance Function
or the Outdoor Function.
A-l
-------
TABLE A-l. HOUSEHOLD FUNCTIONS AND RELATED ACTIVITIES
•Space Heating and Cooling
•Water Heating
•Lighting
•Kitchen
-food preparation
-cooking
-dish washing
•Washing and Cleaning
-clothes washing and drying
-house cleaning
•Bathroom
-toilet
-bathing
-sink
-personal upkeep
•Living and Entertainment
-audio-visual
-hobby
•Outdoors
-gardening
-recreation
-other
•Maintenance
-automotive
-upkeep, repair
A-2
-------
FIGURE A.I. SPACE HEATING: ENERGY/RESIDUALS
.^L
waste heat
^Qualify j |
Heal Transfer
Conventional Heating
%.&
o 3
§*
Central furnace
• hot air
• boiler (hotwater, steam)
Central heat pump
Portable heat pump
Baseboard resistance
Portable resistance
Insulation Effectiveness
Structure
size (area)
Walls insulation (type)
orientation
I Roof
size (area)
color
insulation (type)
Floor
size,(a;ea> ,
insulation (type)
Window
st°rm-type
orientation
Vi/eather stripping
Ventilation
Control System
Act;ve collection
Passive collection
Solar Heating
Heat Transfer
Waste Heat
kitchen, washing,
y
Space to be heated
. J
A-3
-------
FIGURE A.2. COOLING: ENERGY/RESIDUALS
] Solar
5 energy
L.
Conventional Cooling
o 5:2
Centralair conditioning
• chilled H2O
• forced air
Room air conditioning
Central heat pump
Portable neat pump
Insutction Effectiveness
Structure
Wal!s
size (area)
insulation (type)
orientation
size (area)
color; shading
insulation (type)
,-.„
Hoor
size (area)
insulation Uypd
storm- type
^entati
shading
•Window ^entation
Weather stripping
Ventilation
Control System
Solar Cooling
Waste Heat
Kitchen, wasning.
etc.
Space to be cooled j
A-4
-------
The discussion of heating and cooling presents tables which describe the
heating/cooling loads for various kinds of residential structures at various
levels of thermal-structural soundness. We then discuss how these tables
may be used both to estimate the energy needs of new developments and to
ascertain the energy saving value of structural improvements. Next we men-
tion the various types of HVAC systems which might be employed along with
their respective fuels. Residuals generated by the various fuels are then
discussed.
Heating and Cooling Load Tables
Tables were constructed for a variety of typical residential structures
to show heat loss per sq ft per degree day, and cooling load per sq ft per
cooling day.*
Tables were developed for four types of residential dwellings:
1. Single Family, one-story, unattached
2. Single Family, two-story, unattached
3. Attached Split-Level Townhouses
4. 3-story, Low Rise apartments.
Initially, for each of the construction types three different wall materials
(i.e., wood, brick veneer, and aluminum siding) were considered.t However,
because the heat loss coefficients for three wall materials vary by only a
few percent one set of coefficients which is an average of wood and brick
veneer is used. Five levels of thermal soundness are also considered:
1. Uninsulated, no insulation on walls, floor or roof. Single windows.
2. FHA '65,t enough insulation to comply with the 1965 FHA minimum
property standards for federally insured homes.
3. FHA '73, enough insulation to comply with the 1973 FHA minimum
property standards for federally insured homes.
4. ASHRAE 90-75, enough insulation to comply with ASHRAE standards
for heat loss.
5. Best, the maximum amount of insulation for each type of construc-
tion; for example for a frame wall with a 4" space, 3-5/8" of
insulation is the maximum.**
* See Appendix B for method of heat loss calculation.
f These wall types represent construction characteristics reported in Charac-
teristics of New Construction. These types encompass most of the existing
stock of houses as well as new construction.
f See Appendix C for summary of regulations.
** Note; We designed our houses with a combined roof/ceiling, as given in
Thermal Design of Buildings. It is possible to put more roof insulation in
a structure with an unheated attic. Actually, in Section 5 the Best level
of insulation has been increased to 24" in the ceiling and 5-5/8" in the
walls. (See Tables 7 and 8). These changes were made in response to
review comments on the draft report.
A-5
-------
Table A-2 contains the complete array of insulation options. For each struc-
ture at each level of thermal soundness heating load and cooling load (Btu)
per sq ft were calculated.*
TABLE A-2. INSULATION IN STRUCTURES
None
FHA '65
FHA '73
ASHRAE 90-75
Best
Single Family
1-story
Wall
Roof
Window
Floor
-
-
Single
—
-
1"
Single
1 1/2"
1"
3"
Single
1 1/2"
3 5/8"
5"
Single
2"
3 5/8"
6"
Storm
2"
Single Family
2-story
Wall
Roof
Window
Floor
Townhouse
9 Row
Wall
Roof
Window
Floor
3-Story
Low Rise
Wall
Roof
Window
Floor
-
1"
Single Single
1 1/2"
_ i ii
2"
Single Single
— —
_ _
1"
Single Single
— —
1"
3"
Single
1 1/2"
3"
5"
Single
1 1/2"
2"
3"
Single
1 1/2"
3 5/8"
5"
Single
2"
1 1/2"
5"
Single
2"
3 5/8"
4"
Single
2"
3 5/8"
6"
Storm
2"
3 5/8"
6"
Storm
2"
3 5/8"
6"
Storm
2"
The tablestwere constructed assuming a winter indoor temperature of
65°F and summer indoor temperature of 75°F. The figures for the 20 cases in
each table have units of Btu per sq ft of floor area heated (or cooled) per
degree day (or cooling hour). For reasons explained in Appendix B the cool-
ing load tables have two parts, one for an average outdoor temperature of
90°F and the other for a temperature of 85°F. In an example below, use of
both the heating and cooling tables in conjunction with average degree days
and cooling hours for the northeast is demonstrated.
* Details of calculations in Appendix B.
t Tables A-3 and A-4.
A-6
-------
TABLE A-3. HEAT LOSS — BTU/SQ FT/DEGREE DAY
Uninsulated FHA '65 FHA '73 ASHRAE 90-75 Best~
Single Family
1-story 22.4 17.1 11.0 10.3 8.7
Single Family
2-story 19.2 17.3 11.2 9.9 7.9
Townhouse
Split Level 16.8 12.0 8.2 9.2 7.3
Low Rise
3-story 10.8 10.8 6.7 6.2 4.5
TABLE A-4. COOLING LOAD FOR AVERAGE OUTDOOR TEMPERATURE OF 90°F
(Units — Btu/sq ft/cooling hour)
Uninsulated FHA '65 FHA '73 ASHRAE 90-75 Best
Single Family
1-story 40 35 27 24 21
Single Family
2-story
Townhouse
Split Level
Low Rise
3-story
36
24
19
COOLING LOAD
33
19
18
FOR
Uninsulated FHA '
27
15
14
24
16
14
AVERAGE OUTDOOR TEMPERATURE
65 FHA '73
ASHARAE 90-75
21
13
11
OF 85°F
Best
Single Family
1-story 35 31 25 22 19
Single Family
2-story 31 29 24 22 19
Townhouse
Split Level 21 17 14 14 12
Low Rise
3-story 17 16 13 13 11
A-7
-------
Computing Fuel Use and Emissions for Heating and Cooling
A one-story, single family house with 1,500 sq ft of living space con-
structed according to FHA '65 standards loses about 25,650 Btu/degree day
(1,500 sq ft x 17.1 Btu/sq ft/degree day), when the indoor temperature is
kept at 65°F. Multiplying the heat loss 5000 degree days gives an annual
heat loss of 128.25 x 106 Btu. If the residence is equipped with a gas
forced air heating system (conversion efficiency of 75 percent) the total
fuel requirements will be
128.25 x 106 Btu/yr * (1,040 Btu/cu ft x 0.75) = 164.42 x 103 cu ft
of gas. To translate the fuel requirement into emissions the conversion
factors in Table A-5 are used. Total emissions for our example were:
Ibs/yr
Particulates 1.6
S02 0.1
SO3
CO 3.3
Hydrocarbons 1.3
N02 13.1
For a comparison, estimated air emissions for a variety of residential struc-
tures are displayed in Table A-6.
If the calculations are to be done for a different region of the country
an adjustment can be made on the basis of the ratio of degree days. For
example, the average number of degree days per year in Denver, Colorado is
6200. Thus for the same kind of single family house, the heat loss would be
160 x 106 Btu/yr (128.25 x 106 Btu/yr x (6200/5000) with comparable increases
in fuel use and residuals generation. Determining the effect of changing the
thermostat setting is done on the same principle using conversion ratios
found in Table B-3 for various combinations of thermostat setting and aver-
age outdoor temperature. Thus if the thermostat were turned up to 70°F and
the average outdoor temperature were 42°F the heat loss would be 153 x
106 Btu/year.
Energy requirements for cooling are computed in a similar fashion using
the cooling load table in conjunction with average annual cooling hour
figures and average outdoor temperatures. However, with cooling it is not
necessary to calculate air emissions for the household since they occur at
the power plant. With an average outdoor temperature of 85°F during the sum-
mer and an average of 400 cooling hours in the northeast, our single family
house with central air conditioning will have a total cooling load of 21 x
106 Btu =35 Btu/sq ft/cooling hour x 400 cooling hours x 1,500 sq ft. This
is a little less than 20 percent of the heating load.
A-8
-------
TABLE A-5. EMISSION RATES FOR GAS AND OIL (2 )
(LBS/YR)
Particulates
SQ2
so3
CO
Hydrocarbons
N02
HCHO (aldehydes)
a b
Gas Oil
10 10
0.6 142SC
2SC
20 5
8 3
80 12
2
a. Emission rate in lbs/106 cu ft.
b. Emission rate in lbs/10 gal.
c. S is equal to percent by weight of sulfur in oil.
A-9
-------
TABLE A-6. AIR EMISSIONS DUE TO FUEL USE FOR RESIDENTIAL HEATING
•Infill Unit* 540 Unit*
A A
oil (9 in
00 oil
Q'B
llydcoccrbon* ..
Kt>1 oil
HCltO 9*1
1) • 107
.179
1.16
1.79
11.6
.107
164.75
2.32$
3.58
5.8
• 1.43
3.48
14.)
11.9
2.32
96.7
626.0
970.0
6,264.0
58.0
88,9105
1.253S
1,933.0
3,132.0
772.0
1.879.0
7,722.0
7,506.0
1,253.0
•ingl* Unltb
C
9.86 x 107
.1)5
.880
1.15
8. a
.081
125S
1.76S
2.7
4.4
1.08
2.64
10.8
10.6
1.76
540 Unit*
C
72.9
475.0
729.0
4,755.0
44.0
67,5005
950S
1,458.0
2,376.0
583.0
1,426.0
5,830.0
5,724.0
950.0
81nj.lt Unit0
_ I
5.78 x I0r
,0789
.516
.79
5.16
.047
7). IS
1.033
1.58
2.58
.63
1.55
6.3
6.19
1.03
540 Unit*
(
42.6
279.0
427.0
2,786.0
25.0
39.5828
5563
853.0
1,393.0
340. 0
837.0
3,400.0
3,343.0
556,0
Blngl* Unit*
HlttHMfl
Hou**
1.53 X 107
.117
.750
1.17
7.5
.070
106.53
1.53
2.35
3.75
.94
2.25
9.4
9.0
l.SS
540 Unit!
lllM*Mn
Houi*
6). 2
405.0
C32.0
4,050.0
38.0
57,5103
810S
1,269.0
2,025.0
50(1.0
1,215.0
5,000.0
4.Bf.O.O
810.0
• unit**
Hltuun
Mou»»
58 x 107
.83
5.18
8.3
51.8
.498
735S
10.45
16.6
25.9
6.64
15.5
C6.4
62.0
-
540 Unit*
Hltuun
t'MI,
Houte
56.0
350.0
560,0
3,500.0
37.6
49,6125
7O2S
1,120.0
1,748.0
446.0
1,040.0
4,482.0
4.U5.0
-
H
O
Source: "Land-Use-Water Quality Relationship," prepared under contract no. 68-01-2622 for
the Environmental Protection Agency, by Meta Systems Inc, March 1976.
Footnotes; see next page.
-------
Footnotes to Table A-6.
a. House Type A: no insulation, 1500 sq ft, 8 ft ceiling, 70° indoor,
0° outdoor, 4500 degree days, calculation done with Heat Cost Calculator.
b. House Type C: 2" or more of insulation on walls and ceiling, 1500 sq ft-
8 ft ceiling, 70° indoor, 0° outdoor, 4500 degree days, calculation done
with Heat Cost Calculator.
c. House Type E: 6" insulation on ceiling, 2" or more of insulation on
sidewalls, storm sash, 1500 sq ft, 8 ft ceiling, 70° indoor, 0° outdoor,
4500 degree days, calculation done with Heat Cost Calculator.
d. Hittman House: 5" ceiling insulation, 2-1/4" sidewall insulation,
1500 sq ft, 8 ft ceiling, 75° indoor, 10° outdoor, 4500 degree days, cal-
culation done using the aggregate form of the ASHRAE method.
e. Hittman Townhouse: 5" ceiling insulation, 2 air spaces in sidewall, each
unit 1300 sq ft, 8 ft ceilings, townhouses in groups of 8 units — 4 up-
stairs, 75° indoor, 10° outdoor, 4500 degree days, calculation done using
the aggregate form of the ASHRAE method.
f. Gas efficiency assumed 70 percent; oil efficiency assumed 80 percent.
g. For emission factors, see Table A-5.
A-ll
-------
WATER HEATING
Residential water heating utilizes about 15 percent of the total resi-
dential energy consumption for the nation, accounting for about 3.9 (1012)
Btu's in 1970 (3 ). This makes water heating the second most important resi-
dential energy consumption activity, after space heating. Virtually all
dwelling units which have plumbing also have hot water; thus future growth of
energy consumption for this function will depend primarily on population
growth and growth in the per capita use of hot water, not on increased appli-
ance saturation. Figure A.3 shows the flow chart of a residential hot water
heating system.
The two basic types of hot water systems are the direct heating system
and the storage system. In the former, the water is heated as it is being
used, thus the heating device must be sized to deliver the required water
temperature at the maximum design flow rates and minimum design water inlet*
temperature. In many cases the direct water heating system is combined with
the furnace used for space heating. In storage systems water is heated more
slowly and stored in a tank (which usually doubles as the water heater) until
it is needed. In a storage system thermal demands are met partly from the
stored hot water, thereby reducing the size of the heating device required.
The storage system may have somewhat higher initial costs than direct heating,
but allows for more efficient heating element sizing and operation. Overall,
storage systems are usually more economical and are preferred in most new
homes.
In most single family homes, townhouses, and many garden apartments each
individual dwelling unit has its own storage heater. However, in most larger
multiple-unit structures, apartments are served by a single, centralized hot
water system. Such a system entails a more expensive distribution system,
but there are significant countervailing economies. Storage required per
capita or per unit is generally lower because all peak demands do not occur
simultaneously. Also, the storage is more thermally efficient because the
heat transfer surface per unit of volume decreases with increasing tank size
(but losses in the distribution lines are increased). Because of the long
lengths of distribution lines in large apartment buildings, a considerable
amount of water will be stored and will be cooled in the pipes during periods
of low use. Under these conditions it is both inconvenient and wasteful for
the consumer to "let the water run" until hot water is obtained. Thus provi-
sion is made to recirculate water from the pipes back to the storage heater.
The three types of heating elements most commonly employed are gas and
oil burners and electric resistance heaters. Gas heaters are the most popu-
lar, being employed in 48 percent of the occupied dwelling units in the north-
east region, 74 percent of the units in the north central region, 57 percent
In this section we refer to inlet temperature as the temperature of the
cold water entering the heating unit. The outlet temperature is the temper-
ature of the heated water leaving the unit.
A-12
-------
, r
Fuels
coal
oil
gas
wood
electricity
Water
Solar
Energy
Conventional Water Heating
'3
Central system
Individual systems
Heat Transfer
I
Insulation Effectiveness
Storage
Direct
heating
Distribution
to
point of use
Control System
Heat Transfer
Active collection
Passive collection
Solar Heating
Area to be serviced
Sdid Residuals
• coal
•wood
Gaseous
Residuals
.oil
• wood
• coal
•gas
FIGURE A.3. WATER HEATING: MATERIALS, ENERGY, AND RESIDUALS
A-13
-------
of the units in the southern region, and 73 percent of the dwellings in the
western region of the United States.* Electric heaters are the next most
popular, accounting for 15, 24, 39 and 26 percent of occupied dwellings in
the northeast, north central, southern and western regions, respectively.
Fuel oil is an important energy source for hot water heating only in the north-
east, where it is employed in 35 percent of the occupied dwelling units. A
40 gallon gas storage heater currently (i.e., 1977) costs from $130-180 depen-
ding upon the quality of insulation and burner. Prices increase about $10
for each 10 gallon increase in storage capacity. Electric storage heaters
are $30-40 less than gas units for comparable sizes, but the recommended sizes
for similar use are somewhat higher, partly negating the cost difference.
Inputs and Residuals Generation
Table A-7 presents energy and water inputs for the water heating function
and gaseous residuals generated per capita per day. Table A-8 presents these
data on a per day basis. These data indicate that daily per capita direct
energy requirements may range from less than 8,000 up to 30,000 Btu's. Mini-
mum and maximum values for electric heaters are lower than for gas heaters.
In part this difference may reflect incompatibilities in the data sources.
The range reported for electric heaters is based on data provided by Boston
Edison ( 5 ). The values for gas heaters are based on estimates by Hittman
Associates for different dwelling types and household sizes (6 ). These data
agree closely with the range of regional averages reported by the American Gas
Association (7 ). However, despite the difficulty in comparing data from dif-
ferent sources, there is a real difference in the direct energy consumption
between electric and fossil fuel heaters, due primarily to the energy losses
involved in the combustion and heat transfer for the fossil fuels. Under
current ASHRAE guidelines ( 8 ) a gas storage heater designed to supply 80
gallons per day at 140°F and a water temperature rise of 80°F would require
about 26,000 Btu/day more than a comparable electric heater (neglecting the
substantial conversion losses at the power plant). This is a difference of
43 percent. With a pilot-less ignition the differences would be about 17,000
Btu/day. However, if conversion losses at the electric generating plant are
taken into account, then the total energy requirement for electric hot water
heating is about 2.2 times as great as for a conventional gas heater. If
average fuel costs are considered, the electric heater is about 4.1 times as
expensive to operate.t This analysis also suggests another possible reason
why energy consumption is higher for gas heaters. Because gas is much less
expensive per Btu, manufacturers of gas heaters have had less incentive to
improve efficiency than manufacturers of electric heaters, and consumers with
gas heaters have had less incentive to minimize hot water use.
Regions are U.S. Census Regions (4).
Based on national average prices of $1.42/106 Btu for gas and 8.29/105 Btu
for electricity in 1974, as reported in American Gas Association (7).
A-14
-------
TABU: A-7. WATER HEATING ENERGV AND WATER INPUTS AND RESIDUALS GENERATED
{unit/capita/day)
gas heater -
pilot
gas heater -
electric ,
ignition- —
electric
heater
oil
heater
Energy Input—
(BtU) Tn.nl !- r, 1 Wjl^I*- . ..-
/2,5 . , . part.
electric gas oil Input'- (gal)
NA ll'.Tol' ^ 13.1-26.5 _53;4J^J~
* ^ST - "a-26.5 .J'.Jjjpf
' ~ NA NA 9,5-23.7 NA
X NA 13'500/4 13.1-26.5 9-6(10 )
27,200i-1 -19.2(10 4)
Air Emissions
SO NO
2 x
1.0(10~5)— 1.7(10~3) —
-1.7(10"5) -2.8(10"3)
.77(10~5)^. 1.3(10:3)^-
-1.5(10~5) -2.6(10~3)
NA NA
m/7'8 i iqnn~3i/7
-.07 -1.3(10~3)
CO
3.4(10'*) —
-5.6(10'*)
2.6(10^) —
-5.2(10 *)
NA
4.8(10"")^-
-9.6(10'*)
tn
1. Direct energy consumption. Energy loss in power plant conversion is ignored.
2. Total of hot water use of household activities. Should not be added to water use of other activities in
computing total water use.
3. Calculated from estimate with pilot light by assuming heat loads of 9,600 Btu/day for pilot light.
4. Assumed to operate at same efficiency as gas.
5. Assumed hot water temperature = 140°F, average inlet temperature 60°P,efficiencies: electric - 0.80,
gas and oil = 0.65,
6. 1 ft. natural gas = 1,050 Btu.
(continued)
-------
TABLE A-7. (CONTINUED)
7. 1 gal fuel oil = 140,000 Btu.
8. Assumed sulphur content 2.5 percent by weight.
Notes: Where data is given only in units/appliance, conversion to per capita values based upon 3.5 persons/
dwelling unless otherwise specified by source.
NA = not applicable.
X = data not available.
Sources: Energy: Boston Edison (5).
Hittman Associates (6).
American Gas Association (7).
Hittman Associates (9).
Edison Electric Institute (10).
Air Pollutants: U.S. Environmental Protection Agency (2).
-------
I
H
-0
TABLE A-8. WATER HEATING ENERGY AND WATER INPUTS AND RESIDUALS GENERATED
(unit/day)
gas heater -
pilot
gas heater -
electric .,
ignition —
electric
heater
oil
heater
electric
NA
X
27,000-
69,300
X
Energy Input —
(Btu)
gas oil
39,400-
118,400 NA
29,800-
108,000
NA NA
„. 29,800-..
*"* 108,800^
Implied Water
Innui/2'5 (aall part-
29.0-106.0 _2;£jli!-lj~
29.0-106.0 _2;JJjJS-3j~
33.2-83.1 NA
29.0-106.0 _*y™-l]
Air Emissions
SO, NO
2 x
-6.6{10"5) -ll.ldo"3)
-6.2(10"5) -10.2(10~3)
NA NA
/7,8 ' -\ n
-.273 -9.10(10"3)
CO
-2.25(10"3)
.57(10*3) —
-2.10(10~3)
NA
— 3 /7
-3.90(10~3)
1. Direct energy consumption. Energy loss in power plant conversion is ignored.
2. Total of not water use of household activities. Should not be added to water use of other activities in
computing total water use.
3. Calculated from estimate with pilot light by assuming heat loads of 9,600 Btu/day for pilot light.
4. Assumed to operate at same efficiency as gas.
5. Assumed hot water temperature = 140°F, average inlet temperature 60°F, efficiencies: electric = 0.80,
gas and oil = 0.65.
6. 1 ft. natural gas = 1,050 Btu.
(continued)
-------
TABLE A-8. (Continued)
7. 1 gal. fuel oil = 140,000 Btu.
8. Assumed sulphur content 2.5 percent by weight.
Notes: NA = not applicable.
S = data not available.
Sources: Energy: Boston Edison (5).
Hittman Associates (6).
American Gas Association (7).
Hittman Associates (9) .
Edison Electrict Institute (10).
Air Pollutants: U.S. Environmental Protection Agency (2).
t->
CO
-------
The above discussion also indicates the importance of pilot lights in
gas water heating. According to one source a gas pilot utilizes 9,600 Btu/
daY ( 9 ), which is from 8-24 percent of the total consumption, according to
Table A-8. Thus substantial energy savings are possible with electric ignition
systems.
Some types of electric water heaters feature "quick recovery" heating
elements which allow for more rapid heating after the stored water has been
depleted. These heaters draw about 4,500 watts as opposed to 2,500 watts for
standard heaters, and reportedly increase energy consumption by about 14 per-
cent for typical uses (10 ) . However, the rapid recovery heater would require
less storage for any given demand, and the economics for the consumer depend
upon the trade-off between the storage costs and the additional energy costs.
The data in Tables A-7 and A-8 do not reflect seasonal and regional dif-
ferences in energy use. Even if there is no seasonal difference in hot water
use, there will be a difference in energy demands due to differences in inlet
water temperatures. For example, in the northern part of the country the
inlet temperatures might be 40°F in winter and 70°F in summer. For an outlet
temperature of 140°F, this would mean a summer heat load 30 percent less than
in winter, for the same water use and operating efficiency. Regional differ-
ences are also significant. According to data on gas water heater use (Table
A-9), average energy use for water heaters was greatest in the South Atlantic
region, at 98,100 Btu/heater/day and least in the New England region at
66,300 Btu/heater/day, about a third less.
Residential hot water use can be estimated in two ways. First, the
reported energy consumption can be converted to an implied water use by making
explicit assumptions as to thermal efficiency and water inlet and outlet
temperatures. A second approach is to attempt to estimate the hot water use
from individual estimates of the water consumption for each activity and the
associated temperature. The former approach has been employed in deriving the
estimates in Table A-7 and A-8. These estimates place per capita hot water
use at between nine and 27 gallons per day, if a 140°F heater outlet temper-
ature is assumed. Estimates of individual activity use are presented in
Table A-10. These are intended to give ranges of normal household use and
are based on the available literature. For a 120°F water outlet temperature,
a low water use household, which conservatively hand-washes dishes without
continuously running water, does all laundry at a laundromat, and uses the
minimum values listed, would employ an average of 6.2 gal/capita/day, while a
high consuming household, which has a washing machine and automatic dishwasher,
and utilizes the maximum values listed would require almost 80 gal/capita/day.
The latter figure is undoubtedly unrealistic as an average over an extended
period of time, but it indicates the high energy using potential inherent in a
modern home equipped with common appliances.
Gaseous residuals are generated from the combustion of fossil fuels for
water heating. The residuals indicated in Table A-7 and A-8 have been obtained
by applying EPA emission coefficients ( 2 ) to the energy use data, and are
thus strictly proportional to fuel use for any particular fuel type. Since
water heating is responsible for only one-sixth as much energy use as space
heating, and relies mostly on natural gas and electricity, the contribution of
A-19
-------
TABLE A-9. GAS CONSUMPTION FOR WATER HEATING, 1971
Region Consumption (Btu/heater/day)
New England (Conn., Maine, Mass., N.H.
R.I., Vermont) 66,300
Middle Atlantic (N.J., N.Y., Pa.) 87,100
East North Central (111., Ind., Mich.,
Ohio, Wise.) 86,800
West North Central (Iowa, Ka., Minn.,
Mo., Neb., N.D., S.D.) 93,400
South Atlantic (Del., D.C., Fla., Ga.,
Maryland, N.C., S.C., Va.,
W.Va.) 98,100
East South Central (Ala., Ky., Miss., Tenn.) 78,600
West South Central (Ark., La., Oklah., Texas) 87,400
Mountain (Ariz., Col., Idaho, Mont., Nev.,
N.M., Wy.) 71,500
Pacific (Alaska, Cal., Hawaii, Oregon, Washington) 90,100
Source: Adapted from American Gas Association, 1974 Gas Facts, (7).
A-20
-------
TABLE A-10. ESTIMATED HOT WATER USE
Total Water Hot Water Frequency/ Hot Water Use
140° outlet temperature
bath & shower 10-50
dishwasing :
machine 10-17
hand 8-14
Laundry :
hot cycle 25-60
warm wash/
cool rinse 25-70
cleaning 2
other (personal
upkeep, etc.) 1-10
100°F
140°F
110°F
120°F
100°F wash
60°F rinse
120°F
100°F
5-25
10-17
5-9
.
19-45
5-12
1.5
.5-5
.5-1.0
.25-. 5
.30-. 5
0-.5
0-.5
.1-.2
1
2.5-25
2.5-8.5
1.5-4.5
0-22.5
0-6.0
.1-.3
.5-5
120° outlet temperature
aath & shower 10-50
dishwashing :
machine 10-17
hand 8-14
laundry :
hot cycle 25-60
warm wash/
cool rinse 25-70
cleaning 2
other (personal
upkeep, etc.) 1-10
100°F
120°F
110 °F
120°F
100 °F wash
60 °F rinse
120°F
100°F
6.7-33
10-17
6.7-11.7
25-60
6.7-16
2
.7-6.7
.5-1.0
.25-. 5
.30-. 5
0-.5
0-.5
.1-.2
1
3.3-33
2.5-8.5
2-5.8
0-30
0-8
.2-. 4
.7-6.7
Motes: Assumed water
quency of use
inlet temperature 60°F. It has been assumed that fre-
is independent of volume of use.
A-21
-------
gaseous residuals from water heating is a relatively small proportion of
the total residential contribution.
LIGHTING
Energy used for lighting comprises about 15-20 percent of the lighting/
appliance energy load and about one to two percent of the total residential
use in a typical single family home ( 1 ). An average value for energy used
in home lighting is 876 kwh/year, though depending on the household, it could
range anywhere from 500-1,750 kwh/year.
The flow chart (Figure A.4) illustrates the energy used and residuals
(waste heat) generated by the lighting function as well as measures which can
be taken to reduce them.
KITCHEN
The kitchen function includes three major activities; food storage and
preparation, dishwashing, and storage and disposal of solid residuals. Flow
charts describing the materials consumed and residuals generated and the
corresponding energy consumption and residuals flows are presented in Figures
A. 5 and A.6. The Figures indicate the points at which materials (such as food
and other household items and supplies) enter the system and the energy
sources; the appliances using these inputs and generating residuals; inter-
mediate points of entry, such as for residuals from other functions; and exits
for residuals. Alternative appliances and flows of residuals are indicated.
The following "appliances" and their impact on both resource use
and residuals generation* are considered:
Food Storage and Preparation
-refrigerator/freezer (E)
-separate freezer (E)
-stove/oven (E)
-sink (W, WW, LR)
Dishwashing
-sink for manual dishwashing (W, WW, LR)
-automatic dishwasher (W, WW, LR)
E = energy consumption at point of user; W = water use; WW = amount of
wastewater; LR = liquid residuals (in wastewater); SR = solid residuals;
and GR = gaseous residuals.
A-22
-------
Solar
to
GO
Design:
- color
- orientation
- reflective
surfaces
- glazing
I
Lighting
Requirement
- season
- region
Fixtures:
- luminescent
- florescent
- dimmers
- timed switches
Electricity
Waste heat
Input to
heating/cooling
Reflected
Light
FIGURE A.4. LIGHTING — ENERGY/RESIDUALS
-------
HOT
water
Fuel (quality)
electricity
oil
wood
_^
electricity
^
electricity
electricity
gas ^
electricity
gas
electricity
electricity
wood, coal
j*
electricity _
electricity _
Dishwasher
» >
, *—
Sink
~ insiani noi
water
Refrigerator
- standard
- small
maximal
-self-defrost
F-ezer{CuQpSr?ght}
— standard
- small
- self-defrost
Miscellaneous
Appliances
Stove/Oven
- self-cleaning
- microwave
~ double oven
- standard
Garbage
Grinder
Garbage
Compacter
AunnnrntiAn
waste heat
to room
sr
s
waste heat
to room
J
f
waste heat
J\Q room
^s.
waste heat
.to room
/*
(gas)
Part.
NOy
CO
Pnrt
rurii
NO
cox
HC
^ in water y
Heat
for reuse
^
Gaseous residuals
&
Waste heat ^ N.
vented \
Heat
for reuse
(odor filter)
FIGURE A.5. KITCHEN — ENERGY/RESIDUALS
-------
en
Evaporation
r
Dishwashing-J
Water
Dishwasher
BOD, SS, P,N
Evaporation
u
Food Storage M.
and Preparation
Others
bottles, cans
newspapers
packaging
incidentals
Sink
I
BOD, SS, P, N
Waste water
— Central collection
— On-site disposal
(Outdoors)
-* Refrigerator/Freezer
- standard size
- small sire
- manual defrost
- self-defrost
Separate Freezer
- standard size
- small size
Stove /Oven
- self-cleaning
- microwave
- double oven
- standard size
I 1
FIGURE A.6. KITCHEN ~
MATERIALS/RESIDUALS
Storage
and Disposal
of Solid Residi
Garbage
Grinder
BOD!
SS
P.N
Solid Residuals
Container
Compacter
Shute
ols
Clivus Multrum
Compost Heap
(outdoors)
Central
Collection
Central
Collection
Ash
On-site Incinerator
(outdoors)
Gaseous
Residuals
Separated Materials
(Paper, Metal, Glass)
VrujJci, mciui, wnjoo/ *
-Central I
> Collection
- Individual;
Solid Residuals from the Functions--
- Washing/Cleaning
- Bathroom and Bedroom
- Living Entertainment
-------
Storage and Disposal of Residuals
-garbage grinder (E, W, WW, LR)
-compactors (E, SR)
-chutes (gravity or vacuum) (E, SR)
-storage bins for mixed and/or separated solid residuals (LR).
Materials input to the overall kitchen function include foods, supplies
and their packaging, cleaning products, and a variety of incidentals, as well
as the residuals of other functions — such as newspapers, other paper pro-
ducts, cans, bottles and so forth — which are disposed of or stored for dis-
posal in the kitchen. Energy input is required in the form of electricity for
small appliances; electricity, gas, wood or other fuels for stove and oven;
electricity or gas for refrigerator and freezer, and heated water for dish-
washing or other purposes. Water itself is another material input to the
system, particularly for food preparation and dishwashing.
Residuals are made up of liquid residuals which include biochemical
oxygen demand, suspended solids, phosphorous and nitrogen; some gaseous resi-
duals from gas appliances, and indirectly, from hot water heating; and organic
and other solid residuals discarded from the preparation of food or contributed
by other functions. The gaseous residuals generated by appliances are negli-
gible and those caused by hot water heating are considered in the water heating
function.
The interconnections with other systems are most obvious at the points
where solid materials discarded from other household functions enter the
kitchen and are "processed" (collected, compacted, stored) to be disposed of
as residuals, and where the kitchen produces residuals such as organics that
become inputs to another system such as the outdoor function where disposal
can take place in septic tanks, composting or on-site incineration.
Not all appliances associated with kitchen activities are present in every
household. Their availability, size, and usage depends on various user charac-
teristics and patterns of behavior which are discussed below. Points at which
the user can have significant influence over the materials consumed or resi-
duals generated by the activities and associated appliances are marked, in the
flow charts.
Energy Consumption and Residuals Generation
The ranges of resource consumption and residuals generation in the kitchen,
identified in the literature or derived from various sources, are summarized
in Tables A-ll through A-13. Levels of saturation as sampled in 1970 and pro-
jected for 1990 indicate the importance of each appliance in the household.
Energy Consumption—
The consumption and operating characteristics of refrigerators, freezers,
ranges, dishwashers, and garbage grinders were investigated (see Table A-ll,
columns 1 and 2). The probable distribution of other electrical appliances in
households with different energy consumption levels are indicated in Table A-
14. All the yearly values of consumption (kwh/yr) are based on our literature
review.
A-26
-------
TABLE A-ll. APPLIANCES IN KITCHEN AND THEIR RANGE OF RESOURCE USE AND RESIDUAL GENERATION
Refrigerator/ Frost Free
Freezer Manual
Separate Frost Free
Freezer Manual
Range (stove/oven)
Sink
_. , . Automatic
Lusnwasning ,
Manual
Garbage Grinder
Energy*
kwh/yr 10 Btu/cap/day
750-1,790 2.0-4.8
460- 728 1.2-1.9
1,761-1,985 4.7-5.3
1.195-1,320 3.19-3.5
1,142-1,550 3.05-4.14
(2,300-3,100) tt
-
322-380 .86-1.02
- -
9.9-30 .03-. 05
Waterf
and
Wastewater % Saturation t
(gpcd) LR SR 1970 1990
**
- 98 120
28 AK.
— — — 46
(21)
- - 41 75
(28)
2. 7-18. off - >100 >100
(9.9) H)
1.1-6.0 S* 19
1.1-4.6 H (34)
.8-4.0 I
i—1
Storage Bins - - -
Refuse Compactor***
60
O>
to
•v]
* Assumption of 3.5 people per household for per capita energy consumption figure; energy figures
neglect conversion loss at power plant; energy use for hot water heating is accounted for in
Water Heating.
t Evaporative losses are neglected; per capita figures are based on the family sizes encountered in
sampling programs of the authors (see "Bathroom and Bedroom").
(continued)
-------
TABLE A-ll (CONTINUED)
f Figures are based on Project Independence (local and regional differences are documented in the
literature); the figures in parentheses indicate the figures for Southern California.
** 40 percent of the units in operation today, and 70 percent of the ones in operation in 1990 are
of the frost free feature.
tt The figures in parentheses give the consumption figures of gas ranges.
ff 18.0 and 9.9 gpcd include bathroom sinks.
*** Only one source of reference.
?
to
00
-------
TABLE A-12. CHARACTERISTICS OF LIQUID RESIDUALS FROM KITCHEN
(LBS/CAP/DAY)
Sink
Dishwasher
Garbage
Grinder*
BOD5
.018 -
.ooi1-
.024 -
(.021 -
.0233
.0282
.068
.10)
SS
.0051-
.00021-
.035 -
(.03 -
TN
.009 .001 - .002
.0122 .0012
.096 .001 - .002
.14)
TP
.001
.001 - .0022
.000071- .0002
It is reported that on the average .5 Ib/cap/day of garbage
results in .068 Ib BOD5/cap/day and .096 Ib (dry) SS/cap/day;
assuming linear relations in the absence of data, the range
based on the range of garbage disposed (Table A-13 ) would
results in approximately .021-.1 Ib BODs/cap/day and .03-.14
Ib SS/cap/day, respectively. (See K. Ligman, et al., (11)).
the low values are reported in the same study as the low flow
values (Bennett, E. R., et al., (12)).
the high values are reported in the same study as the high flow
values (Witt, M.D. (13)).
high value is reported in the study of low flow value (Bennett,
E. R., et al., (12)).
A-29
-------
TABLE A-13. RANGES OF GENERATION RATES FOR EACH COMPONENT OF RESIDENTIAL SOLID RESIDUALS
(kg/cap/day)
Combined Storage
and Disposal
Separated Stor-
age and Disposal
Organics Disposed
of by Grinder
L
11
L
H
L
H
Organics
.08
.37
.09
.43
.02
.11
Paper
.09
.44
.08
.4
.08
.4
Glass
.06
.29
.06
.29
.06
.29
Metals
.06
.14
.06
.14
.06
.14
Plastics
.01
.09
.01
.09
.01
.09
Rubber
Leather
.005
.04
.005
.04
.005
.04
Textiles
.005
.05
.005
.05
.005
.05
Miscel-
laneous
.002
.02
.002
.02
.002
.02
Total
.31
1.44
.31
1.44
.24
1.13
U)
o
* See Appendix D for derivation of figures (L = low; H = high)
t The totals were calculated under the assumption of independence of the components
leading to extremely high and low values.
-------
TABLE A-14.
APPLIANCES IN KITCHEN FOR HYPOTHETICAL LOW, MEDIUM AND HIGH ENERGY
HOUSEHOLDS.* (BTU IN MILLIONS/YEAR)
Low Btu
Range 4 . 0
Refrigerator 2.5
(manual)
Coffeemaker .5
Toaster . 1
Medium
Range
Refrigerator/
Freezer
Coffeemaker
Frying Pan
Toaster
Btu
4.3
4.0
.5
.3
.1
High
Range
(self cleaning)
Refrigerator/
Freezer
Freezer
Dishwasher
Coffeemaker
Frying Pan
Toaster-Oven
Broiler
Trash Compacter
Toaster
Btu
4.8
4.4
5.0
1.2
.5
.3
.3
.3
.2
.1
OJ
The Btu-values are typical values for these appliances as provided by manufacturers.
-------
Freezers, particularly the frost-free version, are the most energy-
intensive appliances in the kitchen. The saturation figures CTable A-ll)
suggest that there are not many in use because they are expensive to "buy and
run. . The increasing size of refrigerator/freezer combinations will limit the
need for an additional freezer. Another limiting factor is the lack of space
in apartment buildings to accommodate a freezer.
The demand for a separate freezer could arise from such factors as the
scarcity of certain foods (i.e., meats), changing food prices, and the remote-
ness of a household from the store and the resulting convenience of shopping
less frequently.
Manual defrost freezers, frost-free refrigerator/freezer combinations,
and stove and oven units constitute a group of similarly intensive energy
appliances. Manual refrigerator/freezer units and dishwashers consume signi-
ficantly less energy.
Frost-free refrigerators may consume as much as 30-60 percent more energy
than manual units. Nevertheless, the frost-free feature is demanded by custo-
mers; 70 percent of the working units are expected to be frost-free designs in
1990. Currently 40 percent (14 ) of the units are of this type. The lower
kwh/year figure for manual units, however, may be somewhat unrealistic; energy
consumption rises as soon as ice begins to accumulate within the unit, so that
irregular defrosting could lead to an energy consumption as high as that of a
frost-free unit. The time and trouble that defrosting takes is its main draw-
back at the sales counter. Other factors influencing the choice of frost-free
units is their noise level and the fact that some sizes of freezers are only
available in frost-free versions.
Side-by-side refrigerator/freezer combinations are inefficient; they con-
sume approximately 18 percent ( 15 ) more electricity. In an area with an
electricity rate of GC/kwh, the average top-freezer would cost $96.76/year
whereas the side-by-side model would cost $116.64/year, a difference of almost
$20.
Gas refrigeration units are no longer sold in this country; however, some
units are still in operation. In 1968, there were four million gas units,
compared to 57.6 million electric units. A gas refrigerator uses an equivalent
of 4,102 kwh/year compared to 1,270 kwh/year for electric units (16) (neglec-
ting the conversion losses at the power plant).
The average size of refrigerators increased by about one-third of a cu ft
per year during the 1960's. Recently the rate of increase has dropped to one-
sixth of a cu ft per year because of the limits imposed by current building
standards. In 1970 the average size was 13 cu ft (14), and it is now increas-
ing to 14 cu ft.
The saturation level of ranges (stove and oven combined, for our purposes)
has been above 90 percent in the past 20 years; currently it is 97 percent.
Both gas and electric ranges are marketed, but sales of electric ranges began
to outnumber sales of gas ranges during the mid-1960's, even though gas ranges
are cheaper to buy and cheaper to run (in terms of cost of energy consumption).
A-32
-------
Now in the 1970's the number of electric units in operation is actually
larger than the number of gas units. Only on the west coast is the number of
gas ranges sold and in operation greater than the number of electric ranges.
The various sizes of gas and electric ranges account, along with cooking
habits, for variation of energy consumption by these appliances. The American
Gas Association, for example, makes the distinction between house ranges and
apartment ranges. House ranges are estimated to consume on the average 10.5
million But/yr (3,080 kwh/yr) compared to 8.8 million Btu/yr (2,340 kwh/yr)
for apartment ranges.
Dishwashers use eight to nine percent of the central hot water supply in
the home. In the future "virtually all new housing units will have dish-
washers," according to Project Independence's estimate. Thus most of the
energy consumed by the operation of dishwashers is attributable to hot water
demand. Up to 16 gallons of hot water of the central hot water system (about
120°F-140°F) are used per cycle. In models with "sani-wash" features the
water is further heated up to 150°F-155°F. The heating/drying cycle is the
second largest energy consuming factor. Eliminating it would save about
30 percent of energy used in a dishwasher ( 14 ).
Garbage grinders are quite unimportant in terms of their energy consump-
tion, but are included due to their impact on other media.
The typical range and variation in energy consumption implies certain
behavioral patterns and other socio-economic characteristics. To help inter-
pret the implications of the values in Table A-ll, energy consumption by dish-
washers and garbage grinders was calculated, based on various user patterns
(see Table A-15). These calculations show that the lower range of the values
of Table A-ll is quite acceptable, while the upper range values are low for
the dishwasher, but high for the garbage grinder, given our assumption of user
patterns. The scheme of calculations should enable the interested person to
compute possible ranges of energy consumption for specific behavioral patterns.
Water Consumption and Wastewater and Liquid Residuals Generation—
Sinks, dishwashers, and garbage grinders are discussed in this section.
Neglecting losses due to evaporation or food preparation, the wastewater
generated is assumed equal to the amount of water consumed at these points
before evaluation of conservation measures. All water consumption figures are
based on references discussed in more detail in the section on the bathroom
(see below). Many of the values seem to be reasonable and are consistent
among the references, while others are less certain. Consider, for example,
the kitchen sink (exclusive of dishwashing); Laak ( 17 ) assumes three gallons
of water and a generation of 0.001 Ibs BOD5 per event of food preparation. At
two meals per day, on the average, and assuming a family of 3.5 people, the
water consumption would be about 1.71 gpcd. Given an additional one gallon per
handwashing event*the daily consumption of the sink would be about 2.3 gpcd
assuming that the person who prepares the food washes their hands every time.
* See discussion on "Bathroom".
A-33
-------
TABLE A-15. TYPICAL VALUES OF ENERGY CONSUMPTION OF KITCHEN APPLIANCES
U>
Appliance
Dishwasher
-65 min. cycle
39 min. wash-
ing and
26 min. dry-
ing cycle
-14 gallons
- 1/4 hp pump
Garbage
Grinder
Heating
and/or
Driving
Element
750 W
(heating)
1/2 hp
1/3 hp
Heating*
of
Water
for
155°F:
.49 kwh
for
ISO'F:
.33 kwh
for
140<>F:
0
Operation Times
and Consumption
Washing
Cycle
.11 kwh
.11 kwh
.11 kwh
Drying
Cylce
.31 kwh
.31 kwh
.31 kwh
2 min.
2 min.
Total
kwh
per use
.9 it
.75*
.44**
.012
.008
Use
per
day
1
1.5
2
1
1
1
2
1
2
•a
io3
Btu/day
3.10
4.65
6.2
2.6
1.5
.04
.08
.03
.06
Persons
per
Household
2
3.5
4
5
6
7
3.5
3.5
3.5
6
3.5
6
3
10 Btu
cap/day
1.55
0.89
1.16
0.93
1.03
0.89
.7
.43
,012
.01
.01
.01
* Assumed that water from central water heating has temperature of 140"F, and that water has to be
heated up only once to desired °F: 1 Btu x AT x gallon water x 8,
t Use of open door drying would reduce energy consumption by 30 percent.
(continued)
-------
TABLE A-15. (continued)
$ Use of open door drying would reduce energy consumption by 41 percent
** Use of open door drying would reduce energy consumption by 70 percent.
Ul
Ul
-------
If handwashing accounts for a total of 0,011 Ibs BODj/cap/day* and, we assume
that 0.008 Ibs of the 0,011 are generated at the kitchen sink the total does
not approach the lower bound of the BOD from the kitchen sink. If, however,
it is assumed that additional food pieces enter the sink exclusive of the dish-
washing operation, we are easily within the range of the given wastewater char-
acteristics, but would have problems in justifying the lower water use
figures.
The lower value for the water use with an automatic dishwasher is
based on a frequency of use of 0,6/day for 3.8 persons/family and seven gal-
lons per dishwasher use ( 12). This value is very low due to the very conser-
vative use patterns of the families sampled.t The low energy value of Table
A-ll implies four gpcd (14 gallons per day/3.5 people).T Therefore it seems
advisable to select the low value only in cases where very low user frequen-
cies are expected. Also the lower bound of the BOD5 values is quite high
given Laak's value of 0.01 gm BODs/gallon. The low values for both quantity
and quality (BODs) are based on the same sample (Bennett, et al.) (12); Laak's (17)
value is derived from a situation unassessable for us.**
Solid Residuals Generation—
The kitchen function includes the activity "storage and disposal" of
solid residuals generated in all indoors household functions. In addition to
the residuals from activities in the kitchen, solid residuals from other func-
tions are accounted for: lint, inorganics from sweeping the floor, vacuuming,
etc. (washing/cleaning); paper, glass, plastics, textile, rubber, leather
products and other incidentals (bathroom and bedroom), paper, bottles, cans
and other miscellaneous incidentals, such as ashes from fireplaces (living/
entertainment); and ash residuals from individual heating systems fired with
coal and wood (space heating), respectively.
The values of Table A-13 (as derived in Appendix D) imply an average
household of 3.2 persons (average U.S. family size) because the per capita
generation data (used as multiplier for the percentage ranges of each compon-
ent) was derived from a nationwide material flow balance. This is important
for estimating the generation of solid residuals per household.
* See discussion on "Bathroom".
t A survey by K.S. Watson (1963) showed average uses/day of 1.2-1.78 for
families of about four people at a use of 7-12.5 gallons/cycle-(18)«
t It should be pointed out very clearly that the energy figures are based
on reported average consumption figures scaled down to per capita figures
while the water use and liquid residuals generation figures are based
on averages of a small sample of monitored households.
** All values should be accepted for what they are: ranges based on certain
conditions. Low or high values can only be reached under certain combi-
nations of conditions, which are discussed below. But it should be
understood that the ranges are not absolute limits; they reflect liter-
ature values based on small samples, not all possible lower and upper
bounds.
-------
A study of three collection routes in low income areas of Cincinnati (19 )
evaluated the influence of family sizes on the per capita collection rate for
different types of housing. Single-family houses showed an average weekly
per capita generation rate* of 9-10 Ibs (1.29 Ibs/cap/day) for six or more
people, while an averge of 25 Ibs (3.57 Ibs/cap/day) for one person.t Multi-
family dwellings showed an average weekly per capita generation rate of about
8-10 Ibs (1.25 Ibs/cap/day) for ten or more people compared to the average
of 22 Ibs for three to four people per unit (3.14 Ibs/cap/day).f In apart-
ment houses the generation rate was consistently about seven Ibs/person/week
(1.00 Ib/cap/day) for 17-126 people per structure.
According to the average composition data (presented in Table D-l of
Appendix D), paper constituted the single most important component (between
34.4 and 40.8 percent), followed by food (between 22.7 and 27.2 percent).
The amount of paper waste such as newspapers does not increase linearly with
family size; one subscription usually suffices no matter what the family
size. In a small household, printed matter can supply relatively more of the
total waste. Other paper wastes appear correlated with food wastes: the
higher the paper the lower the food content of residuals, presumably because
processed foods, which are heavily packaged, are more completely consumed
but produce residuals from the packaging. Unfortunately, the lack of detailed
socio-economic description of the routes studied does not allow a definitive
interpretation of these results, it is only known that the route with the
lowest paper composition had the highest average number of persons per
single family house, but the lowest number of contributors per multi-family
structure. If the ratio of a single family to multi-family structure is large
*on that route, then the presence of large families should reduce the paper
component according to the above discussion. Quimby (20 ) has estimated that
in 1969, 17 percent of per capita paper consumption is accounted for by news-
papers, resulting in a total of about 98 Ibs newspaper per person/year or
0.27 Ib/cap/day. He also estimated that in metropolitan areas and among
average and higher income groups it is reasonable to posit an average house-
hold consumption of 8-10 Ibs of newspapers per week, which is about 0.37 lb/
cap/day for a family size of 3.5, a number comparable to the national average
of 0.27 Ib/cap/day. In the materials balance ( 21 ) for commercial and resi-
dential solid wastes, roughly 50 percent of the paper component is comprised of
containers and packaging, 25 percent of newspapers, books, and magazines, and
25 percent of other products. Assuming that in residential solid residuals
each of the components contributes one-third, a 0.37 Ib/cap/day newspaper
generation rate could therefore result in 1.07 Ibs/cap/day of paper products.
This figure is still a bit high compared to the estimate of 0.88 in Table A-
13. If paper makes up about 40 percent of the total, a per capita generation
rate of 2.68 Ibs/cap/day would result. Quimby ( 20) estimates that the news-
paper weight of 0.37 Ibs/cap/day (see above) is approximately 15 percent or
* We assume here that the collection rate is equal to the generation rate;
Davidson's report, however, does not address this question at all.
t Family sizes ranged from 1-4 to 1-11 on the different routes.
t People per structure were between 4 and 21, 2 and 26, and 3 and 14 on the
three routes. A-37
-------
more of the weight of residuals generated in residential buildings; this would
yield an upper limit of 2.47 Ibs/cap/day. If the newspaper and magazine
component is 50 percent of the paper component in metropolitan and middle to
high income areas, the 0.74 Ib/cap/day approaches the values of Table A-13;
and if the paper component is about 40 percent of the total weight, a reason-
able total generation rate of about 1.7 Ibs/cap/day results.
The generation of organics is extremely high in Table A-13. The impli-
cation appears to be that much fresh unprocessed fruit, vegetables, and meat
are used in food preparation. This should yield a reduced rate of packaged
material. The few available data show that high garbage residuals are compen-
sated for by low paper residuals.
In general, the range of values of each category seem to reflect reason-
able lower and upper bounds; but the choice of categories whose lower or upper
bounds, respectively, can be added up for low or high total values, has to
be made very carefully.
WASHING AND CLEANING
The washing and cleaning function is comprised of two major activity
types: clothes washing and drying, and room cleaning. Figures A-7 and A-8
depict the flow of energy and materials through the activities and the associ-
ated appliances. Clothes washing and drying includes hand and machine washing,
drying by natural evaporation or by electric or gas heat, and ironing. Energy
inputs are required in the form of hot water for washing, electricity for the
washing machine motor and for the dryer motor and blower, electricity for
resistance heating in the electric dryer and iron, and gas for a gas heated
dryer. Major materials inputs (aside from the clothes themselves) are the
water and soaps, detergents and other cleaning materials. Wastewater is
generated from the washing machine, and contains quantities of BOD, suspended
solids and phosphorus. Solid residuals include lint from the filters in the
dryer and washer, and detergent packaging materials. These are considered in the
solid residuals storage and disposal activity of the kitchen function. Small
amounts of air pollutants are generated by the combustion of gas in the dryer,
by the lint picked up in the dryer exhaust, and indirectly by the combustion of
fuel for hot water. The first two sources of air pollution are considered
insignificant and are not dealt with here. The third source is dealt with
under the function of hot water heating. The clothes washing and drying
activity may account for 2 to 3 percent (Hittman Associates (9)) of the direct
household energy use and 4 to 27 percent of the household water consumption
(Witt, M.D. (13)).
Room cleaning is responsible for a much smaller proportion of total water
and energy requirements. The principal appliances associated with this acti-
vity are vacuum cleaners and electric floor washers and polishers, which
together account for about one-tenth of one percent of direct household energy
input.* Water use for floor washing and cleaning activities accounts for 1 to
* Meta estimate.
A-38
-------
(elec) I wash, machine
size
cycles
water temperature
Hand washing
Dryer
size
cycles
temperature
Other appliances
~7ac u u m
central
loca!
elec. broom
rug cleaner
floor waxer
floor washer
Waste heat to
room
Evaporation and
Conduction
I
Part
NOX
HC
gas
SOX
Waste heat
in water
Energy
SOLAR
Solar drying
(clothesline or
rack)
Evaporation
FIGURE A. 7
WASHING AND GLEANING—ENERGY/RESIDUAL
-------
Water
Clothes
- regular fabric
- permanent press
4*
O
Soaps
and other
materials
Washing machines
size
cycles
temperature
Other appliances
vacuum
central,
local
elec. broom
rug cleaner
floor washer
floor waxer
clothes dryer
SS
P
BOD
Water 8.
Liquid Residuals
Solid Residuals
Container
(Kitchen)
FIGURE A.8
WASHING AND CLEANING—MATERIALS/RESIDUAL
-------
5 percent of total household requirements (Witt, M.D. (13)).
Clothes Washing and Drying Activity
Table A-16 lists ranges of average energy and water consumption and resi-
duals generation by appliances used for clothes washing and drying, expressed
in units of consumption or residuals generation per capita per day. Table A-
17 presents similar information on a per cycle or per use basis. These data,
combined with explicit assumptions as to frequency of use and household size,
will enable the user to compute daily, monthly, or annual figures appropriate
for particular situations.
Clothes Washers—
In 1970 approximately 60 percent of the occupied dwelling units in the
United States had automatic clothes washers, and roughly another 10 percent had
non-automatic washers (4). An automatic washing machine is considered to be
a "standard" appliance for most new single family homes, but traditionally
these appliances have not been common in individual units of multi-family
structures. Washing machines may be provided in common areas of apartments,
and the advent of compact washing machines has made this appliance more prac-
tical for small apartments, although the capacities of the devices are limited.
In dwellings which do not have washing machines a large part of the water
consumption and residuals associated with clothes washing is "exported" to
laundromats and commercial laundries. Only for very low income families, and
in isolated rural areas, would the bulk of clothes washing be done by hand.
Thus it is generally not appropriate to compare the water use of families with
clothes washing machines to those without unless the outside use is taken into
account. In this discussion we consider only households with their own wash-
ing machines or with access to washing machines within the building.
Washing machines are available in a range of sizes and the more recently
produced units feature a variety of control characteristics which enable the
users to tune the operation to their specific needs. A variety of combinations
of water level, operating cycles and wash and rinse temperatures can be selec-
ted, depending upon the types of fabrics and loads involved. Generally speak-
ing, the larger number of options is favorable to conservation of water and
energy if the options are used properly. However, the initial cost of washing
machines, ($250-330/unit (27)) increases with the number of options.
As indicated in Table A-16, the direct electrical energy use of the
washing machine is very small, but the washing machine does contribute signi-
ficantly to the household's water consumption and to the generation of BOD and
suspended solids. It is not a significant source of nitrogen in wastewater,
but is an important source of phosphorus if phosphorus is oresent in the deter-
gents. Washing machine effluent contains about 16 percent of the household's
BOD generation, 12 percent of the suspended solids and up to 50 percent of the
phosphorus where high phosphate detergents are employed.*
* Meta's estimates based on averages from studies cited in Table A-16.
A-41
-------
TABLE A-16. INPUTS AND RESIDUAL OUTPUTS
WASHING AND CLEANING FUNCTION: CLOTHES WASHING AND DRYING
(Units/capita/day}
Washing
Machine
-automatic
-non-
automatic
Dryer
-gas (w.
> pilot)
•u -gas (w/o
t"O
pilot)
-elec-
tric 2,
Iron
(electric)
Energy Use
(Btu)
Electric Gas
235-274 NA
203 NA
178-342 4,697-9,
4
178-342 3,131-6,
645-5,975 HA
160-400 NA
Water Use
(gal.)
4. 2-18. I5
X
3
393 NA
027 NA
NA
NA
Nastewater
(gal.)
4. 2-18. I2
X
NA
NA
NA
NA
won Suspended
BOD5 Solids
(lb) (lb)
.019-. 033 .007-. 024
X X
NA NA
NA NA
NA NA
NA NA
Total
ITitroaer.
(lb)
C.O-.002
X
NA
MA
NA
NA
Total
Phosphorous
(lb)
.0001-. 005
X
NA
m.
NA
NA
1. Does not include hot water energy. Electric energy is only Btu's used at home, not energy used to
generate electricity.
2. Evaporative losses ignored.
3. Pilot light consumes about 880 Btu/day.
4. Does not include electrical energy for ignition.
(continued)
-------
TABLE A-16. (Continued)
5. Water use data for washing machines is based upon a small sample of actual users, while electric use
data was taken from annual averages reported in the sources listed below. As a result the ranges for
the two categories may not be completely consistent.
Notes: Where original data is based upon total household use a conversion factor of 3.5 people/
household is assumed, except where otherwise specified in source.
NA = not applicable.
X = data unavailable.
Sources: Energy:
U)
Water:
Hittman Associates (9).
Edison Electric Institute (10).
Federal Energy Administation (14) .
Association of Home Appliance Manufacturers (22).
Citizen's Advisory Committee on Environmental Quality (23)
Ligman, K., et'al., (11).
Siegrist, R., et al., (24).
Bennett, E.R., and K. Linstedt (25).
Cohen, S. and H. Wallman (26).
-------
TABLE A-17. INPUTS AND RESIDUAL OUTPUTS PER USE
WASHING AND CLEANING FUNCTION: CLOTHES WASHING AND DRYING
Washing
Machine
-automatic
-non-
automatic
Dryer
-gas (w.
pilot)
- gas (w/o
pilot)
-electric
Iron
(electric)
Energy Use
(Btu/event)
Electric
887-990
552
12
682-935
4 12
682-935
9,898-13,652
1,867
Gas
NA
NA
,000-
Water Use
(gal/event)
5
25-71
X
•a
16,500'' NA
,000-
16,500 NA
NA
NA
NA
NA
Wastewater
(gal /event)
25-71
X
NA
NA
NA
NA
tann
BUU
(lb/event)
.062-. 070
X
NA
NA
NA
NA
Suspended
Solids
(lb/event)
.025-. 051
X
NA
NA
NA
NA
Total
Nitrogen
(lb/event)
.00-. 006
X
NA
NA
NA
NA
Total
Phosphorous
(lb/event)
.001-. 015
X
NA
NA
NA
NA
1. Hot water not included. Btu's used to generate electricity not included.
2. Evaporative losses ignored.
3. Pilot light consumes about 880 Btu/day.
4. Does not include electrical energy for ignition.
5. Water use data for washing machines is based upon a small sample of actual users, while electric use
data was taken from annual averages reported in the sources listed below. As a result the ranges for
the two categories may not be completely consistent.
(continued)
-------
TABLE A-17. (Continued)
Notes: Where original data is based upon total household use a conversion factor of 3.5 people/
household is assumed, except where otherwise specified in source.
NA = not applicable.
X = data unavailable.
Sources: Energy:
Water:
*»
en
Hittman Associates (9).
Edison Electric Institute (10).
Federal Energy Administation (14).
Association of Home Appliance Manufacturers (22).
Citizen's Advisory Committee on Environmental Quality (23)
Ligmari, K., et al., (11).
Siegrist, R., et al., (24).
Bennett, E.R., and K. Linstedt (25).
Cohen, S. and H. Wallman (26).
-------
Clothes Dryer—
In homes which have dryers, •these appliances account for about 2 percent
of the household energy use (Hittman Associates (9)). While the majority of
homes which have washing machines also have dryers, a significant number do
not. While about 70 percent of occupied dwelling units had an automatic or
non-automatic washing machine in 1970, the percentage with dryers ranged from
33 to 53, dependent upon the region of the country (4). Among households
with dryers, electric units were preferred by a ratio of 2 to 1 over gas
dryers.
A standard home size dryer unit sells for from $170 to $220 for an elec-
tric unit and $180 to $250 for a gas unit. It employs a 1/4 - 1/3 hp electric
motor to operate the tumbler and blower and uses a 4,000-5,000 watt electric
heater or 1,000-25,000 Btu/hour gas burner to generate the heat needed for
evaporation. Air is heated to about 200°F and leaves at 90°F. Operating times
for dryers vary with the size of load and type of fabric. Average times are
reported to be 0.6 hours for a full load of permanent press fabrics and 0.8
hours for a full load of regular fabrics.
In direct energy use the electric dryer is slightly more efficient than
the gas unit. For a 35 minute cycle the electric unit would utilize about
9,900 Btu, the gas about 12,700 (Hittman Associates (9)). However, when con-
version at the generating plant is taken into account the electric unit is
responsible for 2.2 times as much energy consumption as the gas dryer. Also,
under existing pricing structures the electric dryer is from 5 to 6 times as
expensive to operate as a gas dryer (28).
Iron—
The iron utilizes about the same per capita amount of energy as the
clothes washer, although the range of reported values is greater (Table A-16).
The wider range probably reflects the impacts of personal styles and the influ-
ence of permanent press fabrics.
Floor Cleaning
Floor cleaning includes sweeping, washing, waxing, and vacuuming. Water
use reported for this activity ranges from 0.45 to 2.05 gpcd (13). This reflects
household cleaning habits and cleaning methods. About 1 gallon is employed
to clean a full size room; thus water use for this activity will increase some-
what with total floor area or number of rooms. Water used for cleaning is
usually taken from the sinks or tub and is thus included in the values for
kitchen and bathroom sinks and tub, and is reported elsewhere in the report.
The values listed here should not be added in with the sink and tub values in
aggregating household water use. For the same reason values for wastewater
and waterborne residuals are not reported separately here.
Solid wastes are generated from the dirt and dust collected by sweeping
and vacuuming and from detergent packaging. These are included in the solid
waste storage and disposal activity for the kitchen function.
Principal energy using appliances are the vacuum cleaner and floor washer
and polisher. Average per capita and per event energy uses for these appli-
ances are listed in Table A-18.
A-46
-------
TABLE A-18. ELECTRIC ENERGY USE TOR FLOOR CLEANING
23 2
Btu/capita/day_ ' Btu/event
Vacuum 90,3-122.9 2,218-2,580
Floor polisher 40.1-48.6 980-1,194
1 Direct use, does not include conversion at the generating plant.
2 Computed assuming one vacuuming or polishing "event" per week.
3 Assuming 3.5 persons/household.
Sources: Edison Electric Institute, (10).
Boston Edison, (5).
Citizen's Advisory Committee on Environmental
Quality, (23).
A-47
-------
About 90 percent of households have vacuum cleaners (29), while a much
smaller percentage have floor washers and polishers. Since these units account
for much less than 1 percent of direct household energy use, they do not
represent a major potential for energy reduction. Good maintenance practice,
such as regularly cleaning or replacing the vacuum filter bag will both reduce
energy use and lengthen the operating life of the appliance. Nonelectric
procedures can be substituted for both appliances, but particularly in the case
of vacuums, current home decorating patterns, featuring extensive carpet areas,
reinforce the need for the appliance.
One exception to the low level of energy use in this category is the cen-
tral vacuum system employed in some houses. We do not have quantitative data
on the energy demand for this system, but the presence or absence of such a
system has been found to be significant as a predictor of household electricity
consumption (30).
BATHROOM
Bathroom activities are identified as toilet flushing, bathing (tub and
shower), lavatory use (wash basin), and personal upkeep. Lavatory use is
defined as water use and wastewater generation at the bathroom sink as opposed
to personal upkeep which encompasses the use of electrical appliances such as
hair dryers, water pics, electric shavers, and shaving cream heaters. Some
solid waste, usually in the form of packaging material, is generated by the
latter activity.* Energy used to heat water for bathing and lavatory activi-
ties is discussed in the Water Heating Section; however, the amount of hot
water used for bathing and lavatory use is included in this section. Factors
related to consumer behavior are discussed in this section only if they relate
specifically to bathroom activities.
The flow of materials into and out of the bathroom and bedroom which is
integrated with bathroom activities is shown in Figure A.9. Inputs consist of
paper products (e.g., toilet paper, toothpaste containers, etc.), human waste
(internal and external),t water and reused water, soap and detergent. Addi-
tionally, if a Clivus Multrum type wastewater treatment system is used, organic
kitchen waste from food preparation would also be input. The activities con-
sist of toilet flushing, bathing, and lavatory use. The materials outputs are
waste residuals (e.g., wastewater and compost material which may be inputs to
the outside function and/or back into the bathroom as reuse water), and solid
waste (inputs to the kitchen function). Similarly, the energy flow into and
out of the bathroom is shown in Figure A-10. Energy is consumed in the forms
of hot water and electricity by bathing, lavatory use and personal upkeep;
outputs are hot water and heat.
* Personal upkeep is a minor part of the bathroom activity. In the discussion
of the bathroom function it is confined to the presentation of an estimate
of energy use of small appliances.
t Internal refers to feces and urine, whereas external refers to perspiration,
dirt, oil, etc., that is removed by bathing.
A-48
-------
compost
*»
Municipal
system
Clwus multrum
Kitchen residuals
Chemical
toilet
To storage
of solid
residuals
(kitchen)
Low flush
Standard
Shower
Standard nozzle
Reduced flow
nozzle
Standard tap
Separat hot/cold
Timed tap
Soap and
detergent
Standard volume
Small volume
FIGURE A.9. BATHROOM — RESIDUALS FLOW
-------
Energy
hot water
Ul
o
Energy
Electricity
Evaporation
Shower
Standard nozzle
Reduced flow nozzle
Sink
Standard tap
Separate hot/cold
Timed tap
Tub
Standard volume
Small volume
Evaporation
Municipal
System
(Hot) water
for reuse
(gray water)
Waste Heat
Ultra violet/infrared
lamps —vents, fans
Waste Heat
Miscellaneous
appliances
- shaver-hairdryer
- toothbrush, etc.
Waste heat
in water
I
FIGURE A.10.
BATHROOM — ENERGY FLOW
-------
Conventional Practice
Water Use—
Water use data are shown for various bathroom activities in Table A-19.
Overall residential water use is influenced by numerous factors, as discussed
in Section 4; however, those factors influencing specifically bathroom and
bedroom activities are discussed below.
Toilet flushing—The range of water use for toilet flushing shown in Table
A-19 is from 9.2 gpcd (35.0 Ipcd) to 26.2 gpcd (99.6 Ipcd}.* It has been
reported that toilet flushing accounts for a major fraction of the total house-
hold water use; data show toilet flushing as low as 22 percent (31) and as high
as 45 percent (13) of total daily residential water use.
Usage can be expressed as the product of volume per flush times the number
of flushes per day. Conventional toilets have flushing volumes ranging from
3.0 gallons (11.4 liters), to 5.5 gallons (20.8 liters) (13). Older toilets
often have larger tank volumes and use higher volumes per flush. The frequency
of flushing reported in various studies is shown in Table A-20. No reason
could be found for the lower value of 2.3 since the data represents a wide
variety of family types (herdsman, pharmacist, etc.) and sizes (3 to 7 members),
the coefficient of variation (C.V.), 0.26, for the low value is within the
range of 0.25 to 0.42 for the other table values, and the total water use of
42.6 gpcd (162 Ipcd) agrees with 44.4 gpcd for the higher frequency study.
Data on the frequency of toilet flushing by age group show that the fre-
quency for adults is 4.5 per capita per day, while for both teenagers (13-20
years) and children (1-12 years) the frequency is 2.4 (12).
Combining frequencies and flush volumes, minimum and maximum water use .
values of 6.9 gpcd (26.2 Ipcd) and 24.8 gpcd (94.2 Ipcd), respectively, are
obtained; the range agrees with the literature values shown in Table A-19.
Seasonal data show little difference between warm and cold weather periods.
In Winsconsin (13), summer use is 2 percent greater than winter use whereas
in Connecticut, Rhode Island and California (26), data show winter use 4 per-
cent greater than summer use. These studies include families with children at
school during the winter period, but the effect of their absence during the
school day is minimal.
Cohen's study (26) shows small annual variation with monthly toilet flush-
ings exhibiting C.V. from 0.14 to 0.20 within the study households; the average
variation is 0.16. This is small compared to the variation between the study
households, which have a C.V. of 0.48.
Peak daily values of toilet flushing occur between 7:00 a.m. to 8:00 a.m.
and 6:00 p.m. to 8:00 p.m. These peaks are normally coincident with other
activity peaks and can cause solids wash-out problems in on-site, wastewater
* gpcd is gallons per capita per day and Ipcd is liters per capita per day.
A-51
-------
TABLE A-19. WATER USE FOR BATHROOM (GPCD)
Function
Bath
Shower
Toilet
Lavatory
Total *
R E
123
6.3 20.0 10.0 17
6.3 20.0 10.0 17
17.1 25.0 9.2 26
23.4 45.0 19.2 43.
F E
4
.5
.5
.2
7
REN
5
7.
7.
17.
24
C E-
6
8 11.7
8 11.7
6 18.4
.4 30.1
7 8
10.8 8.
10.8 8.
14.4 14.
2.
8
8
5
0
25.2 25.3
9
20.0
20.0
24.0
44.0
01
to
References:
1. Cohen, S. and H. Wallman, (26) .
2. Bailey, J.R., et al., (31).
3. Witt, M.D., (13) .
4. Haney, P.D. and C.L. Haraann, (32).
5. Laak, R., (33) .
6. Ligman, K., (34).
7. Wallman, H., (35).
8. Bennett, E.R., et al., (12).
9. Reid, G.W., (36).
* Total includes either bath or shower, but not both.
-------
TABLE A-20. FREQUENCY OF TOILET FLUSHING
Frequency
(flushes
per
capita per
day)
Monday
through
Sunday
Saturday
and
Sunday
Ligman* Ligman*
(Rural) (Urban)
3.6 + 1.5 3.6 + 0.9
(mean + std. dev.)
3.8 + 1.6 3.1 + 1.2
Bennett t
3 6
Siegristf
23 + 06
* Ligman, K., et al., (11).
t Bennett, E.R., et al., (12).
t Siegrist, R., et al., (24).
TABLE A-21.
FREQUENCY OF BATHING
Frequency
(Number per capita
per week)
Ligman*
(Rural)
3.1
Ligman*
(Urban)
2.8
Bennett t
2.2
Wittf
3.3
* Ligman, K., et al., (11).
t Bennett, E.R., et al., (12).
f Witt, M., et al., (37).
A-53
-------
treatment systems. The hourly peak has been reported at twice the daily
average flow (12). Maximum daily average use can be 32 percent greater than
the minimum (37) .
Regional data show average toilet flushing volumes of 16.8 gpcd in Con-
necticut and Rhode Island (26), 8.5 gpcd in Wisconsin (37), 14.7 gpcd in
Colorado (12), and 18.2 gpcd in California (26). The low value for Wisconsin
is the result of low frequency of flushing, as previously discussed. No
regional trend is apparent for toilet flushing.
Bathing—The range of water use for bathing, as shown in Table A-19, is
from 6.3 gpcd (23.9 Ipcd) to 20.0 gpcd (76.0 Ipcd). Bathing has been reported
from 18 percent (37) to 37 percent (38) of the total daily residential water
use. Bathing involves either tub or shower use and there is considerable
variation in water use for each. The variability of water use during a shower
is high, due more to the duration per shower than frequency of showering (e.g.,
washing hair can require a longer shower consuming approximately an additional
15 gallons). Data indicate showers can take less (37), the same (12) and more
(+50 percent) (11) water than tub bathing and exhibit a C.V. of 0.49. Studies
have shown that a minimum volume of water for a shower can be 2.5 gallons (12),
while the maximum can be greater than 50 gallons (the shower being limited in
duration to the hot water tank capacity). Shower flow rates can be 5.0 gallons
per minute (gpm) (19.0 1pm) to 10.0 gpm (38.0 1pm) (11). Bathing water use
ranges from 16.3 gallons (61.9 liters) to 31.5 gallons (120 liters) per "event"
(37). Tub bathing uses from 20 gallons (76.0 liters) to 30 gallons (114 liters)
per use. Table A-21 shows the frequency of bathing reported in various studies.
Very little difference exists between the mean frequency of bathing accor-
ding to the data; however, disaggregation according to age group does show a
large difference. The most frequent bathers are the teenage group (from age
13-20) with 5.3 baths per capita per week. Adults bathe at a frequency of
1.9, and children (ages 1-12) at 1.1 (24). Multiplying these minimum and maxi-
mum frequencies of bathing by the minimum and maximum volumes per bathing
event produces a range of 2.6 (9.8 Ipcd) to 23.9 (90.8 Ipcd) gpcd. This range
is broader than shown in Table A-19; the minimum value is obtained from only
child frequency and the maximum from only teenage frequency. Good agreement
exists with the literature values when a realistic aggregated family frequency
is used.
Seasonal data show little difference between water use for warm and cold
weather. May to November data show an average of 6.0 gpcd (22.8 Ipcd) compared
with December to April averages of 7.0 gpcd (26.6 Ipcd) (26). Seasonal dif-
ferences do exist for hot water use as discussed under energy in this section.
Variations within individual households over a year, expressed as C.V.,
show a range of 0.11 to 0.39; the average is 0.26 (26). These same data have
"a C.V. between households of 0.49. Bathing appears to be more variable than
toilet flushing within a household but about the same between households.
Bathing water use peaks at approximately the same hours as toilet flush-
ing, 7:00 a.m. to 9:00 a.m. and 6:00 p.m. to 8:00 p.m. For on-site wastewater
treatment systems, the impact of tub drain rates of 10-15 gpm (38-57 1pm) is
A-54
-------
more severe than shower drain rates of 2-5 gpm (8-20 1pm) due to solids wash-
out potential.
Regional bathing data exhibit no definable trend in water use. In Connec-
ticut and Rhode Island the water use (gpcd) is 6.2 (26); in Wisconsin 9.3 (13);
in Colorado 8.7 (25); and in California 6.6 (26).
Lavatory—Little data exist on water use for the lavatory (bathroom sink).
Studies report total water use for all sinks in the household range from
9.9 gpcd (39.61 Ipcd) (31) to 18.0 gpcd (72 Ipcd) (26). Bennett, et al. (12),
report water use at the sink (including lavatory) to be highly variable ranging
from a "trace" to 48 gallons (192 liters) per event (e.g., washing hair in the
lavatory will greatly increase water use); the mode is 1 gallon (3.8 liters)
and the mean 1.7 gallons (6.5 liters) per "sink" event with a recommended dis-
tribution of 35 percent kitchen and 65 percent bathroom lavatory use. Based
on this apportionment, the lavatory is used daily 3.8 times by adults, 1.9 by
teenagers (13-20 years old) and 2.0 by children (1-12 years). This is approxi-
mately the same ratio as toilet flushing. Using 1.7 gallons (6.5 liters) per
use and the above frequencies, the range of lavatory water use is 3.2 gpcd
(12.2 Ipcd) to 6.5 gpcd (24.7 Ipcd).
Wastewater Generation—
Wastewater residuals for various bathroom activities are discussed below.
The toilet receives primarily human wastes, the sink receives lint and debris
from washing, toothpaste, hair from shaving or hair washing, shampoo, and
other soaps or detergents, etc., and bathing wastewater contains residuals
similar to the sink with the possible addition of urine. However, each acti-
vity could also involve detergents, cleaning solvents, household cleaning
debris, polishes, and numerous other substances, some of which may be toxic.
The constitutents of wastewater considered below are BODs, suspended solids,
total nitrogen and total phosphorus; bacterial concentrations are discussed
for potentially reusable bathing wastewater.
Toilet wastewater—It is estimated that toilet wastewater contains daily
fecal discharge of 100-200 grams (net weight) per capita, urine discharge of
800-1,500 millilitersper capita (mlpc) and toilet paper of 4-20 grams per capita
(gmpc). Associated with these are BOD5 values of 0.32 gm/gm feces, 0.009 gm/
gm urine and 0.20 gm/gm toilet paper (11). Table A-22 shows a range of total
BODs values, 0.015 to 0.083 pounds (Ib) per capita per day and 0.004 to 0.015
Ib per event. The range is smaller considering BODs as "per event," since
frequency data (used to convert to a "per capita" basis) show wide variations
(see water use discussion for toilet flushing in this Section).
Similarly, comparative data for suspended solids presented in Table A-23
show a range of from 0.024 to 0.102 Ib/cap/day. The range per event is narrowed
to 0.017 to 0.022 Ib per event.
The major nutrients, nitrogen and phosphorus, in toilet wastewater are
shown in Table A-24. The range for total nitrogen and total phosphorus is
0.003 to 0.050 and 0.003 to 0.008 Ib/cap/day, respectively.
A-55
-------
TABLE A-22. COMPARISON OF BOD5 DATA FOR TOILET FLUSHING WASTEWATER
BOD 5
(pounds per
capita per
day)
BOD5
(pounds per
event)
Ligman*
°'025
(.017-. 040)
„ . 0.023
Urine(.018-.037)
0.004
Paper(.003-.006)
_ . , 0.052
T0tal(.038-.083)
0.014
Bennett t
0.010
0.005
-
0.015
0.010
Laakf
0.052
0.004
Witt **
0.010
0.014
-
0.024
0.015
**
Ligman, et al. / (11).
Bennett, et al., (12)
Laak, R., (17).
Witt, ejt al. (37).
A-56
-------
TABLE A-23. COMPARISON OF SUSPENDED SOLIDS DATA
FOR TOILET FLUSHING WASTEWATER
Suspended
Solids
(pounds per
capita per
day)
Suspended
Solids
(pounds per
event)
Fecal
Urine
Paper
Total
Total
Ligman*
.048
(.040-. 062)
-
.020
(.010-. 040)
.068
(.050-. 102)
.018
Bennett
.048
-
.032
.080
.022
Wittf
.010
.014
-
.024
.017
* Ligman, et al., (11).
t Bennett, et al., (12).
t Witt, et al., (37).
A-57
-------
TABLE A-24. COMPARISON OF TOTAL NITROGEN AND TOTAL PHOSPHORUS
DATA FOR TOILET FLUSHING WASTEWATER
Total
Nitrogen
(pounds per
capita per
day)
(per event)
Total
Phosphorus
(pounds per
capita per
day)
Total
(per event)
Feces
Urine
Paper
Total
Feces
Urine
Paper
Total
Ligman*
.003
(.001-. 005)
.034
(.002-. 045)
-
.037
(.003-. 050)
.010
.001
(.001-. 004)
.002
(.002-. 004)
-
.003
(.003-. 008)
.001
Laakt
.032
.006
.001
.001
Bennett
.004
.008
-
.012
.003
.002
.001
-
.003
.001
Witt**
.003
.006
-
.009
.006
.001
.001
included
above
.002
.001
* Ligman, et al., (11).
t Laak, R., (17).
$ Bennett, et al., (12).
** Witt, et al., (37).
A-58
-------
The range of total nitrogen per toilet flushing event is 0.003 to 0.010 lb;
a total phosphorus value of 0.001 lb per event, is reported in the study data.
Ligman (34) reports that toilet wastewater suspended solids are 82 percent
volatile, total nitrogen is essentially organic and ammonia type, approximately
50 percent of phosphorus is ortho type, and approximately one-half the BOD5
is removable by filtration.
Toilet wastewater constitutes approximately 21 percent of the total resi-
dential BODs, 37 percent of the total suspended solids, 73 percent of the total
nitrogen and 33 percent of total phosphorus.
Bathing wastewater—Bathing wastewater in the residential sector ranges
from 18 to 37 percent of total residential water use, ranking second in quantity
to toilet flushing (37); it contributes approximately 8 percent of the BOD$
and 4 percent of the suspended solids of the total residential waste load.
These wastewaters provide the best source of potential wastewater reuse within
the household. Table A-25 shows the bacteriological characteristics of the
bathing wastewater. Analysis of isolates suggests that much of the bacterial
contamination of these wastewaters is probably from the natural environment
or the natural skin flora; therefore, their presence in the bathing wastewater
is not considered of great sanitary significance with respect to potential
reuse.
The range of BODs for bathing wastewater in Table A-26 is 0.007 to 0.032
Ib/cap/day; on an event basis, the range is 0.017 to 0.063 lb.
Comparable figures for suspended solids shown in Table A-27 range from
0.002 to 0.042 Ib/cap/day. The range by event is 0.004 to 0.083 lb per event.
The range of BODs and suspended solids values for bathing is not reduced
by considering per event basis. This indicates the wastewater residuals from
an individual bathing event are highly variable in relation to less variable
toilet flushing wastewater when considered on a per event basis.
Most people bathe at their house regardless of their varied daily activi-
ties, whereas toilet flushing can occur outside the house as well as in the
house, depending upon the daily activities. The variation of wastewater resi-
duals for toilet flushing events is strongly dependent upon the physical size
of the contributor or a surrogate, age (i.e., an adult event contributes more
than a child event); the frequency of toilet flushing is influenced by life
style. In contrast, life style influences the wastewater residuals for the
bathing event because of occupation (coal miner vs. school teacher), hobby
(tennis vs. chess) and so forth as well as frequency of bathing; however,
frequency is most dependent upon age as discussed earlier.
Lavatory wastewater—Minimal data exists on segregated lavatory wastewater
characteristics; a summary of available data is shown in Table A-28. The nutri-
ents are zero but the BODs and suspended solids contribution is greater than
from bathing.
A-59
-------
TABLE A-25 ..* BACTERIOLOGICAL CHARACTERISTICS OF BATHING WASTEWATER
Organism
Fecal Streptococci
Fecal Coliforms
Total Coliforms
Range (per 100 mJl)
1-70,000
1-2,500
70-8,200
Geometric Mean (per 100 mi)
44
220
1,100
* Siegrist, etal., (24).
TABLE A-26 . COMPARISON OF BOD DATA FOR BATHING WASTEWATER
BOD 5
(pounds per capita per day)
BOD5
(pounds per event)
Ligman*
0.020
(.011-. 032)
0.039
(.022-. 063)
Bennettf
0.007
0.023
Wittf
0.007
0.017
* Ligman, et al., (11).
t Bennett, et al., (12).
$ Witt, et al., (37).
A-60
-------
TABLE A-27. COMPARISON OF SUSPENDED SOLIDS DATA FOR BATHING WASTEWATER
Suspended Solids
(pounds per capita
per day)
Suspended Solids
(pounds per event)
Ligman*
0.012
(.002-. 042)
0.027
(.004-. 083)
Bennettf
0.002
0.006
Wittl1
0.005
0.013
* Ligman, et al., (11)•
t Bennett, et al., (12).
t Witt, et al., (37).
TABLE A-28. LAVATORY WASTEWATER CHARACTERIZATION
Residual
(pounds per capita
per day)
BOD 5
0.011
Suspended
Solids
0.009
Total
Nitrogen
0.0
Total
Phosphorus
0.0
* Bennett, et al., (12).
A-61
-------
Analysis of some typical products which may be introduced into the lava-
tory wastewater is shown in Table A-29.
Data for lavatory wastewater residuals indicate contributions of approxi-
mately 8 and 6 percent of the residential BODs and suspended solids, respectively.
Energy Use and Air Emissions—
Energy use in the bathroom from lighting is discussed under aggregated
household lighting. Small electrical appliances used for personal upkeep are
shown in Table A-30, estimating the time of use per year, the annual energy
use of these appliances is calculated as 27.3 kwh. The major energy use in
the bathroom is associated with hot water use; it is estimated that approxi-
mately 40 percent of household hot water use occurs in the bathroom (26).
Seasonal variation exists with winter use of hot water for bathing being 30
percent greater than summer use; hot water use in summer is approximately 55
percent of total bathing use. Based upon an aggregate of bathing and lavatory
use, a range of 9.5 to 26.5 gpcd (35.1 to 101 Ipcd) is calculated. The hot
water associated with this range is 5.2 to 14.6 gpcd (19.8 to 55.5 Ipcd) and
6.8 to 19.0 gpcd (25.8 to 72.2 Ipcd) summer and winter use, respectively.
Energy used to heat water is discussed in detail under the Water Heating Section.
The air emission residuals for bathroom and bedroom functions are primarily
associated with space heating (e.g., type of heating system, type of fuel, etc.)
and remote energy generation (i.e., electricity generation). Air emission
residuals are discussed under the Space Heating, Water Heating functions.
LIVING AND ENTERTAINMENT
The major energy-user falling under the category of living and entertain-
ment is the television. As can be seen from Table A-31, a color television
uses more energy than a black and white and a tube television uses more than a
solid state.
The "instant-on" feature with which many televisions are equipped consumes
a significant amount of electricity. This feature is expected to disappear
from new sets.
Other items which may contribute to energy consumption in this category
are stereos, radios, and electric hobbies and games. A stereo uses the same
amount of electricity per hour as does a black and white tube television.
Therefore, in some households it will be a significant energy consumer. Slide
or film projectors are another, minor, energy-user.
Many objects and devices which are used for the entertainment of both
children and adults are a source of solid residuals. The most obvious example
of this are poorly-made toys which break guickly and are then thrown out. Added
to this, energy has been consumed in their production. For this reason, when
discussing conservation in living and entertainment, we must evaluate the pat-
terns of our consumption not only in terms of the durability of the goods we
buy but also in terms of the actual production of these goods.
A-62
-------
TABLE A-29. POTENTIAL CONTRIBUTION OP LAVATORY INPUT MATERIALS
Hair
Care
Hand
Soap
Tooth
Care
Fitch Shampoo
Wella by Balsam
Breck Setting
Lotion
Dial
Unknown
Ultra Brite
Tooth Powder
Ratio*
b
b
b
a
a
a
a
COD
1.024
4.720
0.054
2.355
2.375
3.171
2.602
BOD
.084
.026
XX t
1.809
1.840
0.200
0.082
Total PO -P
0.0
0.0
0.0
0.0
0.0
0.098
0.0001
* a = ratio mg. of pollutant product to mg. of product;
b = gm. of pollutional product to ml. of product.
t xx = material was toxic to BOD testing organism.
Source: Bennett, et al., (12).
A-63
-------
TABLE A-30. ENERGY USE FOR PERSONAL UPKEEP*
Appliances
Hair Dryer
Heat Lamp
Shaver
Total
Wattage
600
250
14
Use Time/Year (hrs)t
39
13
52
Killowatt-hours/year
23.4
3.2
0.7
27.3
* Association of Home Appliance Manufacturers, Edison Electrical
Institute (10).
t Meta Systems average estimate based on much diverting figures in
literature.
A-64
-------
TABLE A-31. ENERGY CONSUMPTION OF TELEVISION
Energy Consumption* % Saturation*
Average Wattage kwh/year 10 Btu/cap/dayt 1970 1990
Black and White 50 - 160 100 - 330 .27 - .88 99 85
Color 175 - 300 350 - 525 .93-1.4 51 98
* The values of the range are comprised of average values given for tube (upper bound)
and solid state (lower bound) in reports of the Edison Electric Institute
t "Project Independence," (14).
t Assumption of 3.5 people/household.
-------
Entertaining guests is a major activity in some families. Depending
upon social tastes and income, entertaining can influence other functions, such
as the Kitchen and Washing and Cleaning in terms of both the amount of energy,
foods and other materials consumed and the amount of residuals produced from
cans and bottles, food waste and packaging, wastewater from dishwashing and so
forth. Large groups of people can contribute greatly to the cooling load as
can extensive use of the stove and oven for food preparation.
Finally, personal hobbies can range from the passive non-consuming sort
(stamp collecting) to a moderately energy-using sort (sewing) to larger energy
and material users such as wood-working and carpentry (assuming power tools).
OUTDOORS
The two most important activities within the outdoors function are garden-
ing and recreation. Of these, gardening uses more resources, particularly
water, and generates a greater volume of residuals in the form of yard clip-
pings, grass and leaves. In the warmer parts of the country recreation might
include a swimming pool, but its water use is a surprisingly small component
of total outdoor water consumption. The greatest users of energy outdoors are
power tools for gardening, swimming pool filter pumps, and lighting for enter-
tainment and recreation. However the requirements are negligible and quanti-
tative estimates are not made. Also, the wastewater generated by outdoor
acitivites is insignificant, except in the cases of consistently over-watering
the lawn or garden. Estimates of outdoor water use and solid waste generation
are discussed below.
Water Use
There are tremendous variations in the estimates of outdoor water use
reported in the literature. Lawn watering and the irrigation of plants and
shrubs, which account for almost all that is used, differ across regions, vary
with the season, and demonstrate a demand behavior which is both price and
income elastic (39). In addition, the amount needed to care for lawns and
shrubs depends on the area of yard available for gardening. Linaweaver (40)
reports that in the West residential units use twice as much water as compar-
able Eastern units and that for the nation as a whole the ratio of summer use
to average annual use is approximately 2.5. Discussing the results of a study
on 39 communities, Howe and Linaweaver (39) estimated that for a subset of these
communities in the West the outdoor water use in the areas with water meters
was 186 g/day per dwelling unit and in the unmetered areas the figure was 420 g/
day per dwelling unit while indoor water use differed by less than 5 percent.
Augmenting the data with metered communities from the East they estimated that
the price elasticity was -1.16 and the income elasticities was 1.07. These
elasticities showed that outdoor use of water is far more sensititive to price
and income than is indoor use.
In reviewing several studies of residential water use Milne (41) concludes
that a reasonable estimate of outdoor use is 70 gpcd. A recent review of
water demand in California, employing data from 1972, reports that total resi-
dential use was approximately 151 gpcd of which 66 gallons or 44 percent was
consumed outdoors primarily for landscape irrigation (42). Andrews (43) found
A-66
-------
in a study of three New Hampshire towns that in two of the towns fewer than
10 percent of the residences watered the lawns at all. However, in the demand
study of Howe and Linaweaver (39), the authors report that during the summer
the mean daily outdoor water use in the unmetered Eastern communities of their
sample was over 1,000 gallons.
Clearly the variation is significant. Nonetheless, except for the case of
the New Hampshire towns, most residences use a considerable amount of water
outdoors during those seasons when the weather is favorable. In some regions
that implies a substantial demand throughout the year.
Solid Residuals
The weight of solid residuals generated by a household in landscaping and
gardening vary widely. As with outdoor water use, seasonal, regional, and
income effects and type of residence are important. However, there are few
data available and most estimates are not based on direct measurements, but
on educated guesses or very small samples. For example, in three studies
containing figures on the composition of residential solid waste for Santa Clara
County, California, the estimate of the percentage by weight of yard wastes in
one study was 23.8 percent, in the second study it was 9 percent and in the
third study is was 34.5 percent (44). Such apparent discrepancies are not
unusual and may depend on nothing more than the time of year when the data
were collected. In a study of municipal solid waste in Springfield, Massa-
chusetts, the percentage of garden waste varied considerably over the four
seasons. In the winter it was 0.0 percent, in the spring 10.0 percent, in
the summer 21.0 percent, and in the fall 34.5 percent (45). Converting these
figures to pounds per household per week (Ib/HH/wk) increases the variation:
Ib/HH/wk
Winter 0.0
Spring 5.4
Summer 9.7
Fall 25.1
With the kind of range exhibited by these estimates it is impractical to
put forward a single figure to be used in all circumstances requiring the calcu-
lation of solid waste load. Nonetheless they do show the importance of yard
wastes as a component of residential solid waste and demonstrate that at cer-
tain times of the year leaves and lawn clippings may be the major items in
solid residuals.
MAINTENANCE
Under the function of maintenance are such activities as upkeep and
repair of the interior and exterior of the residence and care and cleaning
of an automobile. Maintenance of a residence requires small amounts of energy
and water and generates little in the way of residuals. Although no data are
available it is safe to assume that amounts of resources used and residuals
created are negligible. However, an automobile, depending on the habits of its
owners, may be a different matter.
A-67
-------
Automobile Maintenance
Washing a car can require between 150 and 300 gallons of water.* If the
car is washed on an impermeable surface or in the street, a substantial portion
of the water may runoff into the sewer system carrying with it the detergent,
grit, salt, paint and other forms of debris which are washed from the car and
scoured from the driveway and street. If the car is washed on a permeable
surface, most of the water probably infiltrates and there is little runoff.
However, this is another case in which there are no data. The best estimates
available which may be applicable are from a study which includes some data
on self-service auto washers. The pollutants which were measured were total
solids, total volatile solids, suspended solids, volatile suspended solids,
BODs, and oil and grease (46). The results appear in Table A-32. The concen-
trations of total solids, total volatile solids, suspended solids, and grease
are very high. However, the study reports that the average volume of water used
per car is only 20 gallons which is much lower than our estimates of the water
needed when washing a car at home. In the latter case it is reasonable to
assume that the concentration of pollutants would be much lower.
One other auto maintenance activity generates an important residual. The
backyard oil change means that used lubricating oil may be poured in the sewer,
flushed down the toilet, spread on the ground or taken to a collection facility.
Recent estimates of the annual automotive consumption of motor oil place the
figure at 1.1 billion gallons. A little less than half is burned or somehow
lost in the process of lubrication leaving 600 million gallons to be reused or
disposed of in some other way (47). For a long time most of the oil was
drained and replaced at service stations where the used oil was stored and
eventually hauled off to be treated or rerefined for use as a fuel or lubricant
or in the manufacture of asphalt. However, today almost half of the automotive
lubricating oil is sold by discount stores and other outlets (48). People are
now changing the oil in their cars and the used oil is being dumped along with
the lead, copper/ barium, zinc, phosphorus, tin, or chromium it may contain.
This is another case where there are no data on the magnitude or distribution
of the residuals, although it is probably reasonable to assume that in certain
areas the problem may be important.
TABLE A-32. TYPICAL POLLUTANT CONCENTRATIONS IN WASTEWATER FROM
SELF-SERVICE AUTO WASHERS OVER A 10 MONTH PERIOD
(all units mg/1)
Minimum Maximum Average
Total Solids
Total Volatile Solids
Suspended Solids
Volatile Suspended Solids
BOD 5
Grease and Oil
729
207
95
25
15
38
3,334
871
840
116
166
200
2,006
456
386
72
57
86
Assume flow to be between 5 g/min and 10 g/min and time to wash car at
1/2 hour.
A-68
-------
APPENDIX A
REFERENCES
1. Carroll, T. Owen, et al./ Land Use and Energy Utilization (Interim Report),
for Office of Conservation and Environment, Federal Engery Administration,
February 1976, p. 55.
2. U.S. Environmental Protection Agency (EPA), "Compilation of Air Pollutant
Emission Factors," Second Edition, April 1973, AP-42; U.S. EPA, Supplements
#1, 2, and 3 to the above.
3. Committee on Finance, U.S. Senate, Energy Statistics, Washington, D.C.:
U.S. Government Printing Office, July 1975.
4. Census of Housing, 1970, Bureau of Census, Department of Commerce, Washing-
ton, D.C.
5. Boston Edison, "The Wise Use of Energy," Boston, Massachusetts, undated.
6. Hittman Associates, "Multifamily Housing Final Report," prepared for
U.S. Department of Housing and Urban Development, Washington, D.C.: Govern-
ment Printing Office, June 1974.
7. American Gas Association, 1974 Gas Facts, Arlington, Virginia, 1975.
8. American Society of Heating, Refrigeration and Air Conditioning Engineers,
Inc. (ASHRAE), "Energy Conservation in New Building Design," ASHRAE
Standard no. 90-75, 1975.
9. Hittman Associates, "Residential Energy Consumption," Phase I Report, pre-
pared for Department of Housing and Urban Development, March 1972.
10. Edison Electric Institute, "Annual Energy Requirements of Electric House-
hold Appliances," New York, N.Y., 1975.
11. Ligman, K., N. Hutzler, and W.C. Boyle, "Household Wastewater Character-
ization," Journal of Environmental Engineering Division ASCE, 100, EE1,
February 1974, pp. 201-215.
12. Bennett, E.R., K.D. Linstedt and J. Felton, "Comparison of Septic Tank and
Aerobic Treatment Units: The Impact of Wastewater Variations on These
Units," Proceedings of the Rural Environmental Engineering Conference,
University of Vermont, Burlington, Vermont.
13. Witt, M.D., "Water Use in Rural Homes," Small Scale Waste Management Publi-
cation, 1974, 27 pp.
A-69
-------
14. "Project Independence," Federal Energy Administration Project Independence
Blueprint Final Task Force Report, Volume 1, prepared by the Interagency
Task Force on Energy Conservation, under direction of Council on Environ-
mental Quality, November 1974.
15. Consumer Report, December 1975, pp. 7-8.
16. "Patterns of Energy Consumption in the U.S.," Stanford Research Institute,
January 1972.
17. Laak, R., "The Effect of Aerobic and Anaerobic Household Sewage Pretreat-
ment of Sewage Beds," Ph.D. thesis presentation at the University of
Toronto, Toronto, Ontario, Canada, 1966.
18. Watson, K.S., water Requirements of Dishwashers and Food Waste Disposers,
J. AWWA, 55, 555 (1963).
19. Davidson, G.R. , Jr., "A Study of Residential Solid Waste Generated in
Low-Income Areas," EPA-SW-83ts, 1972.
20. Quimby, T., Resource Recovery Conference: Solid Waste Management in
Buildings, November 15-16, 1972.
21. Smith, F.L., "A Solid Waste Estimation Procedure: Material Flows Approach,"
U.S. EPA, SW-147, May 1975.
22. Association of Home Appliance Manufacturers, "Energy Data," Chicago,
Illinois, undated.
23. Citizen's Advisory Committee on Environmental Quality, "Citizen Action
Guide to Energy Conservation," 1973.
24. Siegrist, R., M. Witt, and W.C. Boyle, "Characteristics of Rural Household
Wastewater," Journal of Environmental Engineering Division ASCE, 102,
June 1976, pp. 533-548.
25. Bennett, E.R. and K. Linstedt, "Individual Home Wastewater Characterization
and Treatment," Environmental Resources Center Completion Report Series
no. 66, Colorado State University, Fort Collins, Colorado, July 1975.
26. Cohen, S. and H. Wallman, "Demonstration of Waste Flow Reduction for House-
holds," prepared for U.S. EPA, September 1974, EPA-670/2-74-071.
27. Consumer Report, October 1975.
28. Environment Information Center, Inc., The Energy Index, Volume 3, New
York, N.Y., December 1975.
29. Merchandising Week 102 (8), 1970.
30. Center for Environmental Studies, Princeton University, "Energy Conser-
vation in Housing," continuation proposal submitted to the National Science
Foundation, 1975.
A-70
-------
31. Bailey, J.R., R.J. Benoif, J.L. Dodson, J.M. Robb, and H. Wallman, "A
Study of Flow Reduction and Treatment of Wastewater from Households,"
U.S. EPA, 11050FKE 12/69, December 1969.
32. Haney, P.O. and C.L. Hamann, "Dual Water Systems," Journal American Water
Works Association, 57, September 1965.
33. Laak, R., "Home Plumbing Fixture Waste Flows and Pollutants," Unpublished
report, University of Connecticut, Storrs, Connecticut, 1972.
34. Ligman, K., "Rural Wastewater Simulation," M.S. Independent Study Report,
University of Wisconsin, Madison, Wisconsin, 1972.
35. Wallman, H., "Should We Recycle/Conserve Household Water?" 6th Inter-
national Water Quality Symposium, Washington, D.C., April 18-19, 1972.
36. Reid, G.W., "Projection of Future Municipal Water Requirements," Southwest
Water Works, S. 46:18, 1965.
37. Witt, M., R. Siegrist and W.C. Boyle, "Rural Household Waste-Water Charac-
terization," Proceedings of the National Home Sewage Disposal Symposium,
December 1974, pp. 79-88.
38. "Public Water Supplies in the 100 Largest Cities in the United States,"
U.S. Geological Survey, Water Supply Paper No. 1812, 1962.
39. Howe, W. and F.P. Linaweaver, Jr., "The Impact of Price on Residential
Water Demand and its Relation to System Design and Price Structure,"
Water Resources Research, Volume 3, No. 1, 1967.
40. Linaweaver, F.P., et al., Report V on Phase Two of the Residential Water
Use Project, Department of Environmental Engineering Science, Johns Hopkins
University, 1966.
41. Milne, M., Residential Water Conservation, California Water Resources
Center Report No. 35, March 1976.
42. Water Conservation in California, Department of Water Resources, Bulletin
No. 198, May 1976.
43. Andrews, Richard A., and Martha R. Hammond, Characteristics of Household
Water Consumption in Three New Hampshire Communities, Water Resource
Research Center, University of New Hampshire, December 1970.
44. Niesson, W.R. and S.H. Chansky, "The Nature of Refuse," Proceedings of 1970
National Incinerator Conference, ASME Incinerator Division, Cincinnati,
Ohio, May 17-20, 1970, p. 4; Comprehensive Studies of Solid Waste Manage-
ment - First and Second Reports, HEW, Public Health Service Publication
No. 2039, p. 20; and Darnay, A. and W.E. Franklin, Salvage Markets for
Materials in Solid Wastes, for Environmental Protection Agency, Contract No.
CPE 69-3, 1972, p. 156-2.
A-71
-------
45. Meier, P.M., J. Klihner, and R.E. Bolton, Wet Systems for Residential
Refuse Collection; A Case Study of Springfield, Massachusetts, Report
by Curran Associates, Inc. to EPA Solid and Hazardous Waste Research
Laboratory, Cincinnati, Ohio, March 1974 (published by NTIS, PB-234-
499/AS).
46. Development Document for Proposed Effluent Limitations Guidelines and
New Source Performance Standards to the Auto and Other Laundries, EPA
Office of Enforcement and General Council, April 1974.
47. Decision Makers Guide in Solid Waste Management, EPA Office of Solid
Waste Management Programs, SW-500, 1976.
48. Maugh, Thomas H., II, "Rerefined Oil: An Option that Saves Oil, Mini-
mizes Pollution," Science, Volume 193, 17 September 1976.
A-72
-------
APPENDIX B
HEATING AND COOLING LOAD CALCULATIONS
DESIGN HEATING AND COOLING LOADS
Thermal requirements for different kinds of structures are either of a
prescriptive nature (a maximum thermal resistivity of walls, roof, etc., is
allowed), or performance oriented (a maximum heat loss or gain is allowed dur-
ing a one-hour period at design conditions). Design conditions represent the
most extreme conditions which heating and cooling systems are expected to
handle.*
DESIGN HEAT LOSS CALCULATION
Hourly design heat loss was calculated using the ASHRAE method. There are
two components of heat loss; transmission and infiltration. Transmission
represents the heat lost by conduction through exterior surfaces. It is equal
to the area of the surface multiplied by a conduction coefficient (U) which
varies according to the construction material; this product in turn is multi-
plied by the temperature difference between indoor and out. For a wall area of
1,082 ft.2 with a U coefficient of .08 and a temperature difference of 75°,
1,082 x .08 x 75 = 6,492 Btuh.
This procedure is carried out for all exterior surfaces.
To this is added heat loss due to infiltration of air through cracks and
openings. This is also calculated according to ASHRAE procedures. Modifi-
cations such as weatherstripping and cutting down on door openings are done to
decrease heat loss due to transmission by making it harder for heat to travel
across the boundary (a smaller U value).
Example of Heat Loss Calculation for a 1,500 sqft home (see Table B-l for
dimensions).
• Transmission Loss:
Area U coeff. Temp. Diff. Peat Loss (Btuh)
Walls 1,040 x .06 x 75 = 4,680
Roof 1,740 x .10 x 75 13,050
* Heating systems are designed to be able to handle the temperature difference
between indoor and outdoors which occurs one percent of the time. Accord-
ing to the ASHRAE Standard 90-75, this should be changed to that which occurs
2-1/2 percent of the time.
B-l
-------
TABLE B-l. DIMENSIONS
Sq Ft
Living
Area
Single
Family
One- story 1,500
Single
Family
Two-story 1 , 600
Townhouse
(9 units,
split
level) 11,250
Low- Rise
(27 units,
3-story) 27,000
Sq Ft
First
Floor
Area
1,500
800
6,300
9,000
Sq Ft
Roof
Area
1,740
880
6,300
9,000
Sq Ft
Gross
Exterior
Wall Area
1,280
1,950
7,310
11,960
Sq Ft
Window*
Area
220
240
1,125
2,700
Sq Ft
Net
Wallt
Area
1,060
1,710
6,185
9,260
Ft
Length
X
Width
50x30
38x21
35x20
180x50
Ft.
Peri-
meter
160
118
430
460
Cu Ft
Volume
12,000
12,800
107,100
234,000
Cu Ft
Height
8
16.5
17
26
w
1
NJ
* Window area was assumed to be about 15 percent of floor area for the single family structure and about
10 percent for the other structures.
t Includes door area.
-------
•Transmission Loss (continued)
Area U coeff. Temp^. Diff. Heat Loss (Btuh)
Floor 1,500 x .2 x 30 = 9,000
Windows 192 x 1.13 x 75 = 16,272
Door 42 x .4 x 75 = 1.260
* —r.
Total Transmission Loss (Btuh) 44,262
•Infiltration:* air exchange/hr. x .018 x 12,000tcu ft x 75 = 16,200
•Total Heat Loss 60,462
•Total Heat Loss (Btuh)/sq ft living area 40
DESIGN COOLING LOAD CALCULATION
The components of cooling load are the following:
1. heat gain due to temperature difference between indoors and out;
2. heat gain due to solar radiation;
3. heat gain due to infiltration;
4. heat gain due to occupants;
5. heat gain due to appliances;
6. heat gain through ducts;
7. latent heat load.
The first two are referred to as the sensible cooling load. This encom-
passes heat gain through the outer shell (due to transmission and solar
radiation, the latter figuring larger) and is calculated in the same manner
as transmission heat loss, though instead of using the actual temperature
difference between inside and out, an equivalent temperature difference (ETD)
is used to take account of factors which influence solar radiation. Thus
there will be a different ETD depending on color, mass, and orientation of the
external surfaces.
The cooling load due to components 3-7 have been taken from Thermal Design
of Buildings. They are as follows:
Infiltration — 1.5 Btuh/sg ft of gross exterior wall area;
Occupants — 250 Btuh/person (4 occupants per single family unit;
3.0 occupants per 3-story low-rise unit and townhouse
unit);
Appliances — 1,200 Btuh/unit;
Ducts — 5-15 percent of the sensible heat gain; we assumed 5 percent;
Latent Heat Load — 30 percent of the sensible heat gain.
* See ASHRAE Handbook of Fundamentals.
t Volume of air in structure.
B-3
-------
The total of numbers one through seven, when divided by square footage of
living area, gives cooling load per square foot of living area.
ANNUAL HEATING AND COOLING LOADS
Annual loads are found, in the case of heating, using degree days per year
and in the case of cooling using cooling hours per year. The number of degree
days for an area is the sum of the product of the difference between 65° and
the average daily outdoor temperature (when the outdoor temperature is below
65°) , multiplied by the number of days for which this temperature is recorded.
For example, if it was 25° for 4 days and 30° for two days then,
({65-25) x 4) + ((65-30) x 2) = 210 degrees days.
So these six days contributed 210 degree days to the annual total.
The heating loss figures in Table 8*are given in terms of Btu/sq ft/degree
day. They can be converted to annual loads by multiplying by the annual number
of degree days for the region as found in Table B-2. But since homes are usu-
ally heated to a temperature greater than 65°, Table B-3 should first be used
when calculating annual load.
Cooling hours per year are also found in Table B-2.
THERMAL CONDUCTIVITY OF STRUCTURAL COMPONENTS
Below are the thermal conductance (U) values which were used for walls and
ceilings at different levels of insulation, and also for single windows and
storm windows. The outer wall material is comparable to wood or brick veneer
while the roof material is comparable to asphalt shingle. As levels of insula-
tion increases, outer wall material figures less and less in the overall U
value .
Wall
No Insulation 1" 1-1/2" 2" 3" 3-5/8" 4" 5" 5-5/8"
U .28 .14 .10 .09 .07 .06 .055 .046 .042
Ceiling
No insulation 1" 2" 3" 4" 5" 6" 9" 12" 15" 18" 21" 24"
U .26 .17 .10 .08 .06 .05 .043 .029 .023 .018 .015 .013 .011
Single Window Storm Window
U
1.13 .65
Main report, page 25.
B-4
-------
TABLE B-2. CLIMATIC FACTORS FOR SELECTED CITIES IN THE U.S.
Mobile, Alabama
Anchorage, Alaska
Phoenix, Arizona
Little Rock, Arkansas
Los Angeles, California
San Francisco, California
Denver, Colorado
New Haven, Connecticut
Washington, D.C.
Miami, Florida
Atlanta, Georgia
Honolulu, Hawaii
Boise, Idaho
Chicago, Illinois
Indianapolis, Indiana
Des Moines, Iowa
Kansas City, Kansas
Louisville, Kentucky
New Orleans, Louisiana
Bangor, Maine
Boston, Massachusetts
Battle Creek, Michigan
Duluth, Minnesota
Biloxi, Mississippi
Natchez, Mississippi
Pascagoula, Mississippi
Hannibal, Missouri
Billings, Montana
Lincoln, Nebraska
Las Vegas, Nevada
Concord, New Hampshire
Atlantic City, New Jersey
Alamagordo, New Mexico
Albuquerque, New Mexico
New York, New York
Durham, North Carolina
Minot, North Dakota
Ashtabula, Ohio
Shawnee, Oklahoma
Salem, Oregon
Scranton, Pennsylvania
Winter
Design
Temperature
26
-25
31
19
41
35
-2
5
16
42
18
60
4
-3
0
-7
8
32
-8
6
1
-19
30
22
-1
-10
-4
23
-11
14
18
14
12
15
-24
3
21
2
Winter
Degree
Days
1,600
10,800
1,800
3,200
2,000
3,000
6,200
5,800
4,200
200
3,000
5,800
6,600
5,600
6,600
4,800
4,600
1,400
8,000
5,600
6,600
10,000
1,600
1,800
1,600
5,400
7,000
5,800
2,800
7,400
4,800
3,000
4,400
5,000
3,400
9,600
6,400
3,200
4,800
6,200
Summer
Cooling
Hours
1,850
2,750
2,000
550
<50
650
200
1,000
2,400
1,400
1,350
700
750
750
600
1,100
1,300
1,750
200
400
500
<50
2,050
1,650
2,050
850
500
1,000
2,350
400
450
1,500
1,150
650
1,050
300
400
1,500
300
450
Average Heating
Season Outdoor
Temperature
55
55
50
55
55
40
42^
45
61
50
41
40
42^5
38
42*5
45
55
37h
42%
40
35
55
52^5
52*5
45
37^
40
51
40
46
50
50
45
50
33
42*5
47^
45
42^2
B-5
-------
TABLE B-2. (CONTINUED)
Winter
Design
Temperature
Wilkes-Barre, Pennsylvania 2
Spartanburg, South Carolina 18
Sioux Falls, South Dakota -14
Chattanooga, Tennessee 15
Abilene, Texas 17
Austin, Texas 25
El Paso, Texas 21
Waco, Texas 21
Roanoke, Virginia 15
Spokane, Washington -2
Clarksburg, West Virginia 3
Madison, Wisconsin -9
Casper, Wyoming -11
Winter
Degree
Days
6,200
3,000
7,800
3,200
2,600
1,800
2,800
2,000
4,200
6,600
5,000
7,800
7,400
Summer
Cooling
Hours
450
1,100
500
1,250
2,000
2,250
1,850
2,200
800
350
750
500
550
Average Heating
Season Outdoor
Temperature
35
50
51
52*5
45
42*5
46
37*3
38
B-6
-------
TABLE B-3. INDOOR TEMPERATURE CORRECTION FACTOR
The number of Degree Days per year for an area is equal to the product of
the number of days the house is heated times the average temperature difference
between indoor and out. However, the latter term is arrived at assuming it is
65° indoors. So, if the structure is to be kept at a temperature other than
65°, annual fuel use or annual fuel use reduction due to a conservation measure
must be adjusted by the appropriate multiplicative factor from the table below.
For example, if annual fuel use has been found to be 100 x 106 Btu and the
structure is to be kept at 68° in a region where average heating season tempera-
ture is 35°, then the corrected annual fuel use is: 1.1 x (100 x 106 Btu =
110 x 106 Btu.
Outdoor Average*
Indoor 35 40 45 50 55
65 1.00 1.00 1.00 1.00 1.00
66 1.03 1.04 1.05 1.07 1.10
68 1.10 1.12 1.15 1.20 1.30
70 1.17 1.20 1.25 1.33 1.50
72 1.23 1.28 1.35 1.47 1.70
74 1.30 1.36 1.45 1.60 1.90
Outdoor average heating season temperatures for selected cities are
listed in Table B-2.
B-7
-------
APPENDIX C
HEAT TRANSMISSION COEFFICIENT (U) REQUIREMENTS
HEAT LOSS OF SELECTED THERMAL DESIGN STANDARDS
ONE AND TWO FAMILY — STRUCTURES
1) FHA '65;
Total Heat Loss:
Heat Loss through ceilings:
Heat Loss through slab
on grade:
2) FHA '73;
Total Heat Loss:
Heat Loss through ceilings;
Heat Loss through slab
on grade:
50 Btuh/feq ft of total floor area
heated to 70°F.
U = .06 for ceilings with heating
panels.
U = .15 for ceilings without heating
panels.
5 Btuh/feq ft of floor area.
33 Btu/feq ft for a 1,500 sq ft
house excluding floor loss.*
including floor loss through slab
on grade = 37 Btu/ sq f t
U = .05 for ceilings with heating
panels.
U = .08 for ceilings without heating
panels.
42 Btuh per foot of exposed
slab edge for unheated slabs.
50 Btuh per linear foot of exposed
slab edge for heated slabs.
* The FHA '73 standard gives heat loss excluding loss through floor, as a
function of floor area.
C-l
-------
3) ASHRAE Standard 90-75;
Total Heat Loss:
Heat Loss through
Gross Wall Area:
Not Given. (see below)
U _ = .23
gross wall
(see below)
For a 1500 sq ft house with 8 ft. ceiling, this gives a heat loss (due to
transmission only) of 14 Btuh/sq ft of floor area heated to 70°F.
Heat Loss through Roof
and ceiling:
for roof and ceiling combined
.05, except in the case where the
underside of the roof is essentially
the finished interior surface of the
house as with a wooden cathedral
ceiling. In this case,
U
Heat Loss through slab
on grade:
roof and ceiling
(see below)
= .08.
R of perimeter insulation =4.1 for unheated slab, so heat loss per
linear foot of perimeter =32 Btuh.
R of perimeter insulation = 6.3 for heated slab, so heat loss per linear
foot of perimeter = 25 Btuh.
Brief Explanations of 1) 2) 3);
1) Total heat loss is not given in the standard. But we may do a quick
calculation to see what heat loss will result from conforming to the standard.
70° temperature difference/1,500 sq ft home/perimeter = 160 ft.
Ceiling height = 8 ft./roof area = 1,740 ft.
Walls
Roof/Ceiling
Floor (unheated slab)
Total Transmission
Infiltration
Total
Infiltration assumptions:
21,000 Btuh
6,090 Btuh
5,120 Btuh
32,210 = 21 Btuh/sq ft
14,362 Btuh
46,574 = 31 Btuh/feq ft
70°F temperature difference
12,000 cu ft volume of air
.95 air exchanges per hour (ASHRAE, A.D. Little)
.018 infiltration coefficient (ASHRAE)
If we assumed a cathedral type roof/ceiling, then the loss through roof/
ceiling would be 9,744 Btuh.
C-2
-------
The totals would then be:
35,864 Btuh transmission = 24 Btuh/feq ft
50,228 Btuh transmission = 33 Btuh/feq ft
2) U coefficients are given on the basis of number of degree days. Thus
they will vary over regions^. U=0.23 is the coefficient for an area with
5,000 degree days. The roof and ceiling coefficients are for areas with under
8,000 degree days. For other areas, other coefficients are required.
3) R values of perimeter insulation are given on the basis of degree
days. We chose the values for 5,000 degree days. For others, see chart.
MULTI-FAMILY STRUCTURES
1) FHA '65;
For stories of which neither floor nor ceiling is exposed to an unheated
space, heat loss = 25 Btuh/feq ft story area.
For stories of which either floor or ceiling is•exposed to an unheated
space, heat loss = 35 Btuh/feq ft story area.
For stories of which both floor and ceiling are exposed to unheated
spaces, heat loss = 45 Btuh/feq ft story area.
Ceilings: U = .06 for ceilings with heating
panels.
U = .12 for ceilings without heating
panels.
Floors — Heat Loss = 40 Btuh per linear foot of the slab
(slab on grade) edge.
2) FHA '73:
Total Heat Loss: Not Given
Walls: Masonry U = .05
Frame U = .05
Ceilings: Masonry Wall U = .05
Frame Wall U = .05
Floor, slab on grade Heat loss = 42 Btuh per linear foot
edge (unheated slabs).
Heat loss = 50 Btuh per linear foot
edge (heated slabs).
C-3
-------
3) ASHRAE Standard 90-75;
Total Heat Loss:
Walls:
Roof/Ceiling:
Floor, slab on grade:
Not Given
U ni .30
gross wall area
U = .05, except for roofs the under-
sides of which are the finished interior
surfaces of the ceiling (wooden
cathedral ceilings). In this latter
case U may equal .08.
R. , . =4.1 for unheated slabs =
insulation
32 Btuh loss per linear foot edge.
R , . =6.3 for heated slab =
insulation
25 Btuh loss per linear foot edge.
Note:
Included in ASHRAE Standard 90-75 is a provision which allows for diver-
gence from any of the specific component requirements as long as total heat
loss from the resulting structure is no greater than for a structure in which
all the specific requirements were met.
The following is a comparison of ASHRAE Standard 90-75 with the FHA 1973
Minimum Property Standards using a 1,500 sq ft single family house.
Basic Construction:
Walls — Wood Frame, Wood Siding
Roof — Asphalt Shingle
Floor — Slab on Grade
Total Allowed Heat Loss
Heat Loss/sq ft Living Area
Allowed Heat Loss by Component
Through Gross Wall Area
Per sq ft Wall
Through Roof/Ceiling
Per sq ft Roof/Ceiling
Through Floor Slab
Per linear foot Slab Edge
Total Transmission Loss
Infiltration Loss (/95 air ex/hr)
90-75
none given
none given
23,760 Btuh
18 Btuh
5,400 Btuh
3.6 Btuh
4,640 Btuh
29 Btuh
FHA '73
55,700 Btuh
37 Btuh
30,000 Btuh
23 Btuh
8,640 Btuh
5.8 Btuh
6,720 Btuh
42 Btuh
33,800 Btuh
14,774 Btuh
45,360 Btuh
14,774 Btuh
C-4
-------
Total Loss
48,574 Btuh
32 Btuh
60,134 Btuh
40 Btuh
When considering total heat loss, in the case of FHA "73, it is assumed
that the lowest allowed number is the relevant one and so compare the FHA
overall allowed loss (rather than the sum of the allowed component losses)
with 90-75. So:
ASHRAE 90-75 FHA '75
Total
Per sq ft
48,574 Btuh
32 Btuh
55,700 Btuh
37 Btuh
Thus conforming to the ASHRAE standards lowers loss by 14 percent.
The following are designs for homes which would conform to each of the
standards.
ASHRAE House
3 inches wall insulation
6 inches ceiling insulation
single windows
2 inches slab insulation
FHA '73 House
1 1/2 inches wall insulation*
3 inches ceiling insulation
single windows
1 1/3 inches slab insulation
Heat Loss by Component for Each of the Houses
wall
window
rooff
floor
infiltration
ASHRAE 90-75
5,484
15,621
6,264
4,000
14,774
46,143
31 Btuh
FHA '73
7,834
15,621
10,022
6,080
14,774
54,331
36 Btuh
Conforming to ASHRAE standards 90-75 thus lowers heat loss by 14 percent.
* About 7,000 Btuh are saved over the allowed component loss thereby bringing
the sum of the component and insulation losses in line with the total
allowed loss.
t Because of indivisibilities in infiltration, etc., these losses are
slightly lower than the allowed.
f The roof in this case is assumed to be on a slope so that its area is
1,740 sq ft.
C-5
-------
APPENDIX D
RESIDENTIAL SOLID RESIDUALS
In the literature terms like solid wastes, garbage, refuse and rubbish
are frequently used interchangeably. We apply the following terminology:
Solid residual is the most general expression; it refers to the useless, un-
wanted, or discarded materials resulting from society's activities, including
dewatered sludges from treatment plants, organics from kitchens, fly ash from
stack discharges, etc.* We refer to residential solid residuals for all
items discarded by residents, and to garbage (organics) as the animal and veg-
etable waste resulting from handling, preparing, cooking, and serving foods,
especially from residential kitchens. Bulky wastes are large items from resi-
dential and commercial sources and from public property and vacant lots, which
are frequently difficult to handle and therefore require separate collection.
Refrigerators, TVs, and mattresses are items of this type from households.
In general, solid residual quantities differ within cities, from city to
city, from region to region, and from season to season. The per capita amount
collected is affected both by the amount generated, and by the amount of
source separation and voluntary recycling, on-site burning, house and apart-
ment incineration, food waste grinding, etc. The per capita amount actually
generated by the household depends on the economy, standard of living, size
and age structure of family, new products and packaging development, heating
system (coal or wood), institutional arrangements (such as scavenger ordi- '
nances or container legislations), availability of storage, and behavioral
patterns such as number and types of newspapers, magazines and periodicals
read, cooking (fresh versus canned, frozen or packaged food), entertainment
habits, etc. The per capita quantity of garbage and ashes seems to be
decreasing, while the amount of combustible material, especially paper and
plastics, is increasing. These trends imply a change in per capita quantity
as well as in the composition of residential refuse. Climate can influence
the degree of seasonal fluctuations in solid residuals quantity and composi-
tion. For example, in the north, combustibles (yard wastes and clean up)
account for peaks in the spring, and sometimes also in summer and early fall,
while leaves produce yearly peaks of quantity and large shifts in the composi-
tion in the period of October to December. Table D-l indicates the materials
which are associated with each major component of residential solid residuals.
The amount of materials actually collected for off-site disposal might
be quite different from that generated. Container regulations, recycling
of glass, metals, and paper on a voluntary or mandatory basis, on-site
The general definition of residuals is given in Section 1 of the main
report (p. 1).
D-l
-------
disposal (burning or composting), storage of magazines in basement, etc., will
reduce the collection rate for central waste disposal. Open containers might
be responsible for increased moisture content during rainy seasons; for ex-
ample, Partridge and Harrington* showed that high moisture content influences
collection time for containers unprotected against rain on the collection day.
TABLE D-f. DESCRIPTION OF RESIDENTIAL SOLID RESIDUALS'^
Category Description
Food wastes garbage
Glass bottles (primarily)
Metal cans, wire, and foil
Paper various types, some with fillers
Plastics Polyvinyl chloride. Polyethylene,
Styrene, etc., as found in packaging,
housewares, furniture, toys, and non-
woven synthetics.
Textiles cellulosic, protein, woven synthetics
Leather, Rubber shoes, tires, toys, etc.
Wood wooden packaging, furniture, logs,
twigs
Miscellaneous inorganic ash, stones, dust
Yard wastes grass, brush, shrub trimmings
t Table 10, in W.R. Niessen and S.H. Chansky, "The Nature of Refuse," Pro-
ceedings of 1970 National Incinerator Conference, ASME, 1970.
Because of these factors, there is no single good estimate of per capita
generation and collection rate and corresponding composition. Results from
various studies of the composition of residential solid residual collection
indicate a wide range of percentage weight in the categories which are largely
* Partridge, L.J., and J.J. Harrington, "Multivariate Study of Refuse Col-
lection Efficiency," Journal of Environmental Engineering Division, ASCE,
Vol. 100, No. EE4, August 1974, pp. 963-978.
D-2
-------
influenced by indoors residuals.* The range of values from the studies which
were recorded by the National Center for Resource Recovery, and their average
value as calculated by Meta Systems is presented in Table D-2, rows A and B
Unfortunately, most of the original sources were not accessible. But Darnay
and Franklin^ have characterized some of the sources regarding the origin of
residuals (residential or residential and commercial), year and time of year
of sampling. All samples cited by Darnay and Franklin were taken between 1966
and 1969, and were composed both of residential and commercial residuals and
most samples were taken either in the winter or summer; only one community,
Flint, Michigan, was sampled at different seasons. The highest percentage of
garbage was encountered in Flint, Michigan, in January, while the lowest one,
which was not considered to be influenced by garbage grinders, occurred in
Weber County, Utah, in April 1968. The high value in Flint is associated with
a relatively low value for paper (21.1 percent),* while the low value in Utah
is associated with the highest percentage of paper (61.8 percent). The col-
lection in Flint is exclusively a residential collection, while the other is a
collection of residential and commercial wastes. Commercial wastes might
increase the percentage of paper. Some of the exclusively residential collec-
tions, however, also yielded quite high rates.
In addition to the highest proportion of garbage, the highest glass and
metal components were also found in Flint, in Jaunary, with 23.2 and 13.2 per-
cent respectively. The same proportion of glass was encountered in Flint in
June. The lowest percentages of glass showed up in Weber County, Utah, the
place with the lowest garbage component. The lowest proportion of metals is
reported in a study of Madison. No other obvious facts could be extracted
from information on the glass, metal, and plastic components. In some cases,
all three components were relatively high or low, and in some cases they
showed contrary trends without any clear pattern.
* Resource Recovery from Municipal Solid Waste, National Center for Resource
Recovery, Inc., Lexington Books, D.C. Heath and Company, Lexington, Massa-
chusetts, 1974: Table 2-4, "Surveys of the Composition of Municipal
Solid Waste in the U.S."; and, W.R. Niessen and S.H. Chansky , "The Nature
of Refuse," Proceedings^of the 1970 National Incincerator Conference,
May 17-20, 1970, New York, American Society of Mechanical Engineers, p. 14.
t Darnay, A., and W.E. Franklin, "Salvage Markets for Materials in Solid
Wastes," Study prepared by Midwest Research Institute, U.S. EPA, SW-29c,
1972.
T This might partially be explained by the practice of backyard burning in
Flint, Michigan (see, Thomas H.E. Ouimby, "Recycling - The Alternative
to Disposal," The Johns Hopkins University Press, Baltimore, 1975).
D-3
-------
D
TABLE D-2. COMPONENTS OF SOLID RESIDUALS GENERATED INDOORS
(by porcentage weight)
aource
A
B
C
D
Metals
Non-
Food Misc. Glass Ferrous Ferrous Paper Plastics Textile
L 8.5
H 36.0
17.6
Mean 19.3
SD 10.95
CV .57
35* confidence
4.73
ft of samples:
23
L 22.7
H 27.2
,2 4.6 5.4 .3 13.0 .3 .3
2.0 23.2 13.2 1.3 61.8 3.8 8.9
1.1 10.3 7.9* .9 42.7 1.7 2.4
9.9 10.2 51.6 1.4 2.7
4.37 2.18 11.67 .96 1.8
.44 .21 .23 .69 .67
interval:
1.139 .93 5.04 .74 .93
23 23 23 9 17
11.3 8.4 34.4 1.1
14.5 10.2 46.4 3.0
Rubber/
Leather Wood
.3 .3
4.7 6.6
1.8 2.5
1.9 3.0
1.62 2.39
.85 .8
1.25 1.06
9 22
1.6 .12
2 . 8t . 67
* Average of 8.8 was assumed for all metals. t Including plastics.
A. Range extracted from Table 2-4, Resource Recovery from Municipal Solid Waste, op. cit., p. 13.
B. Average percentages from A (not adjusted to 100%).
C. Table 2, in W.R. Niessen and S.H. Chanski, op. cit. (note: some samples of A are contained in C).
D. Davidson, G.R. , "A Study of Residential Solid Waste Generated in Low.-Income Areas," U.S. Environmental
Protectional Agency SW-83ts, 1972; Summary of Table 5 describing components in percentage for three
routes.
Legend • L = low value of range; H = hiqh value of rancrp;
SD = standard deviations; CV = coefficient of variation
-------
It is questionable whether the data for Flint can be used to hypothesize
general tendencies. The sample size is too small, and none of the other
important characteristics of the area are known. One could argue, for example,
that if the metal and bottle generation rate is high, a relatively low garbage
generation rate should be expected; a large number of glass containers for
soft drinks and beer should cause a relatively low number of metal containers
for these products; a high rate of both metals and glass is probably caused by
the number of metal containers for food products, which in turn should imply a
low garbage rate.
Row C reflects the data analysis performed by Niessen and Chansky . The
relatively small coefficients of variation indicate that the average figures
might be reasonable first estimates of a community's solid waste composition
by weight. Row D of Table D-2 reflects results from sampling of composition
in low income areas of Cincinnati. The range of values, derived from the
average composition of three routes of mixed housing (single family and multi-
family dwellings and apartment buildings) sampled over a period of three weeks,
was presented for the purpose of comparison. All values fall well into the
established ranges.
Table D-3 indicates the change of the composition over the yearly
seasons. The variation is very much influenced by the complementary changes
of the paper and the non-fiber organics component. The portion of yard
wastes including grass clippings, leaves, etc. is largely dependent on local
and regional characteristics. In order to utilize the figures of Table D-3,
they have to be converted to absolute amounts of waste. The available sources
did not give the total weights for every sample so that relations between
changing composition and actual weight cannot be established from these data.
It is difficult to make reasonable assumptions regarding an appropriate
daily per capita generation rate which could be used to derive ranges for
daily per capita generation of the various components from the data on pro-
portions. Due to the lack of good data on average daily per capita genera-
tion, figures were estimated from a nationwide materials flow analysis of
residential solid residuals by the resource recovery division of the Office
of Solid Waste Management Programs.* Values are reported on an "as-generated"
and on "as-disposed" weight basis. The difference between the two estimates
is caused by the exchange of moisture from food residuals to paper products.'
Niessen and Chansky's estimates of moisture contentt in municipal solid wastes
"as discarded" and "as disposed" basis were used to calculate the corresponding
* Smith, F.L., "A Solid Waste Estimation Procedure: Material Flows Approach,
U.S. Environmental Protection Agency, SW-147, May 1975.
t Estimates of the waste "as generated" imply an "air dry" moisture content
of paper products at seven percent (industry assumes six percent); glass
and metals at zero; and the remaining materials at 3-15 percent. The
total waste flow is estimated to contain about 26 percent moisture overall.
I Niessen, W.R. and S.H. Chansky, op. cit.
D-5
-------
daily per capita generation rates.* These two figures were assumed to be
reasonable base estimates for calculating the range of generation rates in
each category for the case of disposal by mixed waste, garbage grinder, and
separate garbage bins. The following figures are used (see Table D-4): for
combined disposal, the "as disposed" weight figures,r and for disposal by
garbage grinder the "as generated" weight figures of the non-food residuals
TABLE D-3. SEASONAL VARIATION OF REFUSE COMPOSITION:
FRANKLIN, OHIO
CATEGORY
Paper
Spring
4/10-4/18/74
SORT DATES
Fall Winter
9/17-9/23/74 12/16/12/ /74
33.8
37.34
49.4
Newspaper
Corrugated
Magazines
Strong Paper
Mixed Paper
Inert
Glass
Metals
6.83
2.5
1-5
3.86
19.12
2.5
9.7
13.48
5.80
2.17
3.71
12.18
5.18
7.94
12.1
4.9
1.3
3.8
27.3
2.4
8.0
Average
40.1
10.8
4.4
1.7
3.8
19.5
3.4
8.5
10.7
11.88
10.7
11.1
Magnetic
Non-Magnetic
10.05
.62
10.10
1.78
9.3
1.4
9.8
1.3
Non-fiber
organics
44.2
37.39
29.5
37.0
* Values in percent.
Source: U.S. Environmental Protection Agency, A Technical, Environmental, and
Economic Evaluation of the Wet Processing System for the Recovery
and Disposal of Municipal Solid Waste (Sw-109C), 1975.
* See Niessen, W.R. and S.H. Chansty, op. cit.
t Smith's figures were slightly changed by eliminating the moisture transfer from
yard wastes to paper, which was assumed to be a quarter of the moisture
accumulation in paper.
D-6
-------
plus a small amount of garbage which is not disposed of through the grinder.
This garbage is assumed to transfer no moisture to the paper component.*
TABLE D-4. MATERIAL-FLOW ESTIMATES OF RESIDENTIAL SOLID
RESIDUAL GENERATION (Ibs/cap/day)*
Paper
Glass
Metals
Plastics
Rubber & Leather
Textiles
Miscellaneous
"As Generated"
Weight-Basis
0.61
0.29
0.19
0.08
0.03
0.03
0.02
"As Disposed"
Weight- Basis
0.67
0.29
0.19
0.09
0.03
0.03
0.02
Subtotal: Non-Food 1-25 1.32
Food Waste 0.47 0.40
Total: Non-Bulky Product Waste 1.72 1.72
* Based on data of Smith F.A. and F.L. Smith, Resource Recovery Division,
Office of Solid Waste Management Programs, February 1974.
* One-fourth of food waste ("as generated" weight) is believed to reflect
these items resulting in .12 Ib/cap/day; for example, McKinney and J.L.
Mahloch state that 3/4 of the total garbage can easily be ground up
("The Economic Evaluation of Garbage Grinding vs. Surface Collection and
Disposal," Water and Sewage Works^ 1971.)
D-7
-------
The range of daily per capita generation rates was calculated by assuming
that the average value of the percentage weight of each component (Table D-2,
How B) agrees with the average generation rate of each component, as calcu-
lated in Table D-4.* The resulting ranges are shown in Table D-5. The under-
lying assumption for the calculations provides an operational way of deriving
the ranges in absolute values, even though the resulting ranges are biased.
Collection values reported by Rhyner^match very well with our figures.
We chose to use the average values, calculated by Meta Systems, instead
of Niessen and Chansky's values because we felt more comfortable with
our own derivations.
Rhyner, C.R., Domestic Solid Waste and Household Characteristics, Waste Age,
April 1976,
D-8
-------
TABLE D-5. RANGES OF GENERATION RATES FOR EACH COMPONENT OF RESIDENTIAL SOLID RESIDUALS
(kq/cap/day)
V
vo
Organics Paper
Combined
Storage and Disposal
Separated
Storage and Disposal
Organics Disposed of
by Grinder
Urban
*Wisconsin
Rural
Urban
*Southern State
Rural
L
H
L
H
L
H
M
SD
M
SD
M
SD
M
SD
.08
.37
.09
.43
.02
.11
.114
.09
.114
.090
.139
.13
.132
.14
.09
.44
.08
.40
.08
.4
.198
.123
.15
.105
.218
.157
.171
.138
Glass
.06
.29
.06
.29
.06
.29
.122
.093
.078
.056
.099
.076X
.091
.067
Metals
.06
.14
.06
.14
.06
.14
.075
.104
.059
.064
.097
.114 '
.092
.116
Rubber
Plastics Leather
.01 .005
.09 .04
.01 .005
.09 .04
.01 .005
-.09 .04
.025
.03
.02
.033
.03
.039
.028
.042
Textiles? Misc.
.005 .002
.05 .02
.005 .002
.05 .02
.005 .002
.05 .02
.046
.088
.045
.103
.058
.093
.054
.087
Total
.31
1.44
.31
1.44
.24
1.13
.58
.245
.466
.212
.641
.276
.568
.265
* Rhyner, C.R., op. cit.
Legend: L = ] ow
H = hiqh
M = mean
SD = standard deviation
-------
Appendix E
CALCULATION OF BASELINE USE AND GENERATION ESTIMATES
In this appendix examples are presented which illustrate the procedure
used to calculate the baseline resource use and residuals generation estimates.
The computations for the energy use and gaseous residuals baselines are
explained first. The water use and liquid residuals estimates are discussed
next and the solid residuals estimating procedure is presented last. All of
the examples are taken from the "single family house" high baseline.
In Table E-l some of the general characteristics of the baseline are
listed. The size of the structure (1500 square feet of living space) and its
TABLE E-l. GENERAL CHARACTERISTICS OF BASELINE
"SINGLE FAMILY HOUSE"
Structure Type; One-story detached; no basement; 1,500 square feet
Lot Size; 1/4 acre
Location; Southern New England (5,000 degree days/year; average outdoor heating
season temperature 45°F; 400 cooling hours/year; average outdoor
cooling season temperature 85°F)
Size of Household; 4 persons (2 adults and 2 children)
location (Southern New England) influence the energy requirement. The lot size
(1/4 acre) and the number of occupants influence the water use and solid
residuals generation and to some extent energy use—particularly through the
volume of hot water used. In addition to these general characteristics, speci-
fic features which have direct effects on energy or water use and residuals
generation are attributed to structure in the context of the relevant baselines.
ENERGY AND GASEOUS RESIDUALS
Each of the household functions and the features which determine its
energy use appear in Table E-2. The actual steps of the estimating procedure
follow;
E-l
-------
TABLE E-2. SPECIFIC ENERGY USE CHARACTERISTICS
Heating
Built to FHA '65 heat loss specifications; gas forced-air heating; 65 percent
efficiency; thermostat setting of 72°F (no reduction overnight); all rooms
are heated all the time.
Cooling
Central cooling system; thermostat setting of 75°F; (65 percent efficiency).
Water Heating
Central supply and storage system; gas furnace with pilot light; 50 gallon
storage tank; inlet temperature of 60°F; outlet temperature of 140°F; and
ambient air temperature 70°F.
Kitchen
Appliances include a self-cleaning gas range (stove/oven) with pilot light,
refrigerator (frost-free feature), separate freezer (frost-free feature),
dishwasher, and other appliances.
Washing/Cleaning
Washing machine, electric dryer, and miscellaneous small appliances are
available; washing machine and dryer are each run once a day on the average.
Bathroom
Miscellaneous small energy using devices (e.g. hair dryer, electric
toothbrush).
Living/Entertainment
Color TV (with instant-on feature) and radio/stereo equipment.
E-2
-------
1. Heating:
a. For a one-story single family house built to FHA '65 specifications
the heat loss is 17.1 Btu/sq ft/Degree Day (See Table 8)
b. Annual heat loss: 1,500 sq ft x 5,000 Degree DaysAear x 17.1 =
128.2 x 10 Btu/year;
c. To correct for a furnace efficiency of 65 percent the total Btu
figure is divided by .65
(I/.65) x 128.2 x 106 = 197.2 x 1Q6 Btu of fuel/year;
d. The correction factor for an indoor thermostat temperature "of 72°
in a region where the average outdoor temperature is 45° is equal
to 1.35*. So, 1.35 x 197.2 x 106 = 266.4 x 106 Btu of fuel/year
(The fuel requirement is equivalent to 256,200 cubic feet of gas assuming
1,040 Btu/cu ft).
2. Cooling:
a. The cooling load is 31 Btu/sq ft/cooling hour/or an outdoor tempera-
ture of 85°F (See Table 9)
b. Annual cooling load: 1,500 sq ft x 400 cooling hours x 31.0 =
18.6 x 106 Btu/yr
c. For an efficiency of .65; (I/.65) x 18.6 x 10 = 28.6 x 10 Btu/yr.
(The requirement is equivalent to 8.38 x 10 kwh/yr.)
3. Water Heating:
a. It is assumed that the outlet temperature (OT) is 140°F. However,
the temperature (T) for hot water uses (X,) varies and an equivalent
water use (@ 140°F) (Xj) has to be calculated, given an inlet
temperature (IT) of 60°F. The following expression is used:
Xx (OT-IT) = X2 (T-IT)
T-IT „
Xj_ = X2
- IT
We assume the following amounts of water are used (X2) at the temperatures
given in the second column. The equivalent amounts of water at 140°F
appear under X]_.
* See Table B-3, Indoor Temperature Correction Factor, Appendix B, page B-7.
E-3
-------
X2 (gal/day) T(°F) KI (gal/day)
Dishwasher 16 140 16
Bathing 60 100 30
Sinks (B,K) 24 100 12
Washing 45 120 30
Miscellaneous 10 100 5
Total 155 93 gal/day
b. The standby heat loss is calculated using the coefficients which
appear in Table E-3. For a tank of 50 gallons and a conversion
loss of 30%, the coefficient is .73. Assuming the temperature dif-
ference between the water and the ambient air is 70°F:
173 Btu/gal/day/AT) x 70°F x 93 gal/day = 4,752 Btu/day
c. The energy requirement to heat the water is:
93 gal/day x (140°F - 60°F) x 8.34 Btu/gal = 62,050 Btu/day
d. Assuming a conversion efficiency of 70% (as above) and assuming the
pilot uses 9,600 Btu/day and provides some heat (conversion
efficiency of .5) the total energy requirement for one year is
305[(4,752 Btu/day + 62,050 Btu/day -.5 (9,600 Btu/day))/.7 + 9,600]
= 35.8 x 106 Btu/yr.
TABLE E-3. STANDBY HEAT LOSS COEFFICIENTS (ASHRAE)
(Btu/gal/AT where AT is the difference in °F between the ambient
temperature and the water temperature)
Tank size (gallons)
Conversion Loss (%) 50 55 60 65 70
30
35
40
4 . Lighting :
a. Appendix A indicates a rar
.73 .71
.79 .77
.86 .84
ige of 500-1,750 k
.70 .69
.76 .75
.82 .81
wh/year (1.4-4.8
.68
.74
.80
kwh/day) .
A consumption at the high end has been assumed: 4.8 kwh/day.
b. This is equivalent to approximately 6 x 106 Btu/yr.
E-4
-------
5. Kitchen;
Table 13, 14 and 38* are used to derive the energy consumption of kit-
chen appliances. It was assumed that the values at the upper bound
would reflect the high use case:
Million
Btu/year
dishwasher (except water heating) 1.2
refrigerator (frost-free w/anti-condensation heater) 4.4
separate freezer (frost-free w/anti-condensation heater) 5.0
others 1.5
Subtotal 12.1
self-cleaning gas range (stove/oven)
with a pilot light
whereby the pilot light uses
about 6,000 Btu/day 4.8
Total 16.9
6. Washing/Cleaning:
Table A-17 (Appendix A, page A-44) contains values of energy con-
sumption on an event basis. We had assumed one use per day,
106 Btu/yr
Automatic Washing Machine (20 gallons)
(excluding energy consumption for hot water) .5
Electric Dryer 7.5
Miscellaneous .3
Total 8.3
7. Bathroom (see Table A-30; Appendix A, page A-64)
Miscellaneous: approximately 0.1 x 106 Btu/yr.
8. Living/Entertainment:(see Table A-32)
kwh/year 106 Btu/yr
Color TV with instant-on feature 525 1.8
Radio/Stereo 150 .5
Miscellaneous (such as hobbies) 100 .3
775 kwh/yr = 2.6
9. Outdoors & Maintenance:
No consumption.
These estimates comprise the high energy use baseline in Section 7 (main report)
* See main report, pp. 33, 35, and 74.
E-5
-------
The gaseous residuals are computed using the ratios in Table A-5 and the
energy requirements (in cu ft of gas) for heating, water heating, and the kit-
chen range. The residuals (in Ibs/yr) are:
Heating
Water Heating
Kitchen range
Parti culates
2.6
0.3
—
SO2
0.2
-
••"
SO 3
—
-
—
CO
5.2
0.7
0.1
Hydrocarbons
2.1
0.3
•"
NO2
20.6
2.7
0.4
Total (pounds/yr) 2.9 0.2 - 6.0 2.4 23.7
These estimates become part of the high baseline in Section 7.
WATER AND LIQUID RESIDUALS
The household characteristics which influence water use and liquid resid-
uals generation appear in Table E-4. It is assumed that the residence has a
garbage grinder, dishwasher, washing machine, and two bathrooms. The garbage
grinder and dishwasher are used twice a day and the washing machine once a day.
The residence has a large lawn (8500 sq ft) which is watered through the spring
and summer.
TABLE E-4.SPECIFIC CHARACTERISTICS FOR WATER USE AND LIQUID
RESIDUALS BASELINE.
High Water Use
Kitchen Bathroom Other
—sink -two bathrooms, -washing machine
-garbage grinder first with tub and (one load/day)
(2 uses/day) shower, second with -8500 sq ft of lawn
-dishwasher shower only. Each -car washed once
(2 loads/day) with conventional every month
toilet (6 gallon
tank) and sink
The following water use figures are estimated on the basis of ranges of
water consumption found in the studies reviewed in Section 5 and Appendix A
and the specified frequencies of use presented below:
Quantity Total
Frequency of per Use Water Use
Use (times/day) (gallons) (gallon/yr)
Kitchen
sink 12 2 8,760
garbage grinder 2 6 4,380
dishwasher 2 16 11,680
(FIGURES CONTINUED ON NEXT PAGE)
E-6
-------
(FIGURES CONTINUED)
Quantity Total
Frequency of per Use Water Use
Use (times/day) (gallons) (gallon/yr)
Bathroom
toilet 20 6 43,800
bathing 2 30 21,900
sink 6 2 4,380
Cleaning
washing machine 1 45 15 425
miscellaneous - 3 550
Subtotal 114,975
Outdoor
Lawn (assume .25 inches of water/week for 22 weeks) 29,200
Car wash (assume once every 4 weeks and 40 gallons) 3,650
Subtotal 32,850
Total 147,825
The estimates of liquid residuals for inclusion in the baseline are again
taken from the studies reviewed in Section 5 and Appendix A. They coincide
with the water use figures above and are within the range of the per capita or
per event generation rates reported in these studies. Also, we make the
assumption that, with the exception of lawn watering, water is not consumed in
use. The hydraulic waste load is equivalent to the total water used. The
daily and annual liquid residuals estimates are in Table E-5. These estimates
appear as the high water use and liquid residuals baseline in Section 7.
SOLID RESIDUALS
Factors which influence the generation of solid residuals appear in
Table E-6. The estimates are based on the figures in Table A-13. The upper
range is used for all components (e.g., paper, glass, metal, etc.) all except
food waste because of the presence of a garbage grinder. We assume that 95
percent of food waste is disposed of using the grinder. The daily per capita
rate by component is:
E-7
-------
TABLE E-5, LIQUID RESIDUALS
(Ibs/year)
BOD5 SS TN
Kitchen
-sink 2.92 7.7 1.5
-garbage grinder 116.8 131.4 1.5
-dishwasher 21.9 8.8 1.5
Bathroom
-toilet 43.8 65.7 29,2
-bathing 14.6 8.8 1,5
-sink 14.6 13.1
Cleaning
-washing machine 37.2 7.5 1.5
Maintenance
-carwash .1 .8
TP
1.5
1.5
3.0
4.4
Grease and Oil
.4
Total
278.2
243.8
36.7
7.8
.2
TABLE E-6. FACTORS INFLUENCING THE GENERATION OF SOLID RESIDUALS
Administrative
. grinder ordinance
. factor price {paper
good but variable,
aluminum 17C/lb)
. separate collection
newspaper (I/month)
(a little unreli-
able; no good
advertisement)
Physical
. no compost heap for
garden waste
. recycling center avail-
able (but only on volun-
tary participation
except for newspaper)
Behavioral
. family eats regular-
ly at home; typical
food being a mixture
of fresh and pre-
cooked meals
. all organics are
ground by garbage
grinder (if possible)
. non-returnable beer
and soft drink cans
. regular local morn-
ing newspaper (not
very big); Sunday
newspaper
. Occasional separation
of newspaper (1/3
month). If they are
not picked up they
get thrown away with
regular collection.
E-8
-------
kg/cap
per day
Food 0,02
Paper 0,40
Glass 0.29
Metals 0.14
Miscellaneous (plastic, rubber, leather, etc.) 0.20
Garden 0.23
1.28
We assume now that 40 percent of the paper component (.16 kg/cap/day) is
newspaper and that one third of the used newspaper is recycled. The generation
rate is then 1.28 - (.16 x 1/3) = 1.23 kg/cap/day. On an annual basis for a
family of four the solid residuals are 1,795 kg. This is the estimate used in
the high baseline. The component figures appear in Table E-7. With the solid
residuals estimates the resources and residuals baselir^s are complete.
TABLE E-7. HIGH BASELINE SOLID RESIDUALS
BY COMPONENT
Component Generation Rate
(kg/yr)
Food
Paper
Glass
Metals
Miscellaneous
Garden
Total 1795
E-9
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA 600/5-79-005
2.
3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
Resource Use and Residuals Generation in Households
5. REPORT DATE
March. 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J. Kuhner, D.F. Luecke, M. Shapiro
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Meta Systems, Inc.
10 Hoiworthy Street
Cambridge, MA 02138
1HC619
11. CONTRACT/GRANT NO.
68-01-2622
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
U.S. Environmental Protection Agency
Office of Research & Development (RD-682)
Washington, D.C. 20460
14. SPONSORING AGENCY CODE
EPA/600 (ORD)
16. SUPPLEMENTARY NOTES
16. ABSTRACT
This report describes, for households, resource use (energy and water only),
the generation of liquid, solid and gaseous residuals (other energy residuals are
not discussed, e.g., heat, noise, etc.), potential conservation measures and the
direct costs, to the household, associated with these measures. This study
focuses on nine major household functions and associated activities and their
relative importance for resource use and residuals generation. In considering
conservation measures, attention is focused on new structures and factor prices
are assumed fixed. The household activities are organized by function, and the
behavioral, physical and institutional factors which influence energy and water
use and the residuals generation are identified. The relevant literature is
critically reviewed to provide a basis for estimating use and generation rates
and for assessing the influence, where possible, of the factors on these rates.
Conservation measures and estimates of their performance and cost are presented.
Resource use and residuals generation rates and conservation measures are brought
together in the context of the factors which influence them, by utilizing two
baselines -or benchmarks developed for single family residences. Conservation
measures are imposed on the baselines, direct costs to the households are calcu-
lated and the relative attractiveness of the measures is determined.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTlFIERS/OPEN ENDED TERMS C. COSATI Field/Group
*Residuals Generation, *Resource
Conservation, *Planning, Urbanization,
Local Government
institutions, *Environ-
mental Control,
Institutional Constraints
6E
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
* U.S. GOVERNMENT PRINTING OFFICE: 1979 -281-147/29
------- |