United States	Indoor Environments	liPA-402-S-01-001D
Environmental	Division (6609J)	January 2000
Protection	Office of air and Radiation
Agency	
Energy Cost and IAQ
Performance of Ventilation
Systems and Controls
Project # 4
Impacts of Increased Outdoor Air Flow Rates
on Annual HVAC Energy Costs

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Energy Cost and IAQ Performance of Ventilation Systems
and Controls
Project Report # 4 Impacts of Increased Outdoor Air Flow Rates on
Annual HVAC Energy Costs
Indoor Environments Division
Office of Radiation and Indoor Air
Office of Air and Radiation
United States Environmental Protection Agency
Washington, D C. 20460
January 2000

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Energy Cost and IAQ Performance of Ventilation Systems and Controls
Project Report #4: Impacts of Increased Outdoor Air Flow Rates on Annual HVAC
Energy Costs
INTRODUCTION
Purpose and Scope of this Report
Conventional wisdom in energy conservation circles suggests that the introduction of outdoor air
into the building, while necessary to some extent for indoor air quality, is a major source of energy
use in buildings. This is because outdoor air must be conditioned prior to being delivered to the
occupied spaces, and since about half of a building's energy budget goes to condition the air, it
has been considered wise to minimize the entry of outdoor air. During the energy crises of the
1970's and early 1980's, it was not uncommon for building personnel to close or seal shut the
outdoor dampers which provide the building with its outdoor ventilation.
In order to achieve acceptable indoor air quality in office environments, ASHRAE's latest
ventilation standard (Standard 62-19991) raised the recommended outdoor air ventilation rates
from 5 cfm/occupant to 20 cfm/occupant. This four-fold increase in ventilation rates was contrary to
common energy conservation practices and has raised a number of questions concerning the
feasibility and cost of implementing this standard.
In contrast to this conventional wisdom, when the outdoor air is cooler than the return air, it is
common practice to employ an economizer strategy which provides "free cooling" by increasing
outdoor air flow. This strategy saves energy by reducing the need for mechanical cooling. Thus,
raising outdoor airflow rates may either increase or decrease energy use depending on the
outdoor air climate and the thermal demands of the indoor space.
Since outdoor air flow is important to the maintenance of indoor air quality, it is worthwhile to
examine the relationship between outdoor airflow and energy use in more detail. This report
examines the energy and energy cost impact of raising outdoor air ventilation rates in office
1 This project was initiated wliile ASHRAE Standard 1989 was in effect. However, since the outdoor air flow rates
for both the 19S9 and 1999 versions are the same, all references to ASHRAE Standard 62 in this report are stated as
ASHRAE Standard 62-1999.
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buildings using both CV and VAV ventilation configurations. A sensitivity analysis is performed to
determine how this impact is affected by various building parameters, economizers, and climate.
Comparisons are made between ventilation systems that provide a minimum of 5 and 20 cfm of
outdoor air per occupant during all occupied hours.
This analysis is applicable to new building construction, and for existing buildings with sufficient
equipment capacity to accommodate both outdoor air ventilation rates. The impacts of raising
outdoor ventilation rates on ventilation system capacity in existing buildings are examined in a
companion report (Project Report # 5).
Background
This report is part of a larger modeling project to assess the compatibilities and trade-offs between
energy, indoor air, and thermal comfort objectives in the design and operation of HVAC systems in
commercial buildings, and to shed light on potential strategies which can simultaneously achieve
superior performance on each objective.
This is a modeling study, subject to all the limitations and inadequacies inherent in using models to
reflect real world conditions that are complex and considerably more varied than can be fully
represented in a single study. Nevertheless, it is hoped that this project will make a useful
contribution to understanding the relationships studied, so that together with other information,
including field research results, professionals and practitioners who design and operate ventilation
systems will be better able to save energy without sacrificing thermal comfort or outdoor air flow
performance.
The methodology used in this project has been to refine and adapt the DOE-2.1E building energy
analysis computer program for the specific needs of this study, and to generate a detailed
database on the energy use. indoor climate, and outdoor air flow rates of various ventilation
systems and control strategies. Constant volume (CV) and variable air volume (VAV) systems in
different buildings, with different outdoor air control strategies, in alternative climates, provided the
basis for parametric variations in the database.
Seven reports, covering the following topics, describe the findings of this project:
•	Project Report #1: Project objective and detailed description of the modeling methodology and
database development
•	Project Report #2; Assessment of energy and outdoor air flow rates in CV and VAV ventilation
systems for large office buildings:
•	Project Report #3: Assessment of the distribution of outdoor air and the control of thermal
comfort in CV and VAV systems for large office buildings
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• Project Report #4: Energy impacts of increasing outdoor air flow rates from 5 to 20 cfm per
occupant in large office buildings
•	Project Report #5: Peak load impacts of increasing outdoor airflow rates from 5 to 20 cfm per
occupant in large office buildings
•	Project Report #6: Potential problems in IAQ and energy performance of HVAC systems when
outdoor airflow rates are increased from 5 to 15 cfm per occupant in
auditoriums, education, and other buildings with very high occupant density
•	Project Report #7: The energy cost of protecting indoor environmental quality during energy
efficiency projects for office and education buildings
DESCRIPTION OF THE BUILDINGS AND VENTILATION SYSTEMS MODELED
A large 12 story office building (Building A), along with 13 additional parametric variations
(Buildings B-N) were modeled in three different climates representing cold (Minneapolis),
temperate (Washington, D.C.), and hot/humid (Miami) climate zones. All buildings have an air
handler on each floor servicing four perimeter zones corresponding to the four compass
orientations, and a core zone, A dual duct constant volume (CV) system, and a single duct variable
volume (VAV) system with reheat were modeled using alternative outdoor air control strategies.
Constant volume systems control the thermal conditions in the space by altering the temperature of
a constant volume of supply air. VAV systems provide control by altering the supply air volume
while maintaining a constant supply air temperature. The fourteen building and HVAC
configurations used in this analysis are summarized in Exhibit 1.
The CV and VAV systems were each modeled using 5 cfm and 20 cfm of outdoor air per
occupant. The system for both runs was sized to accommodate the heating and cooling load of 20
cfm per occupant rather than being separately sized for each case. This analysis therefore applies
to existing buildings which may be operating at 5 cfm, but have sufficient excess capacity to
operate at 20 cfm per occupant. In addition, this sizing strategy would also apply to new
construction. A companion report discusses the HVAC capacity implications of raising outdoor air
flow rates in existing buildings (see Project Report # 5).
Comparisons were then made between the two runs (5 cfm and 20 cfm per occupant) to determine
the impact of an increased outdoor airflow rate on energy consumption and cost. The basic
outdoor air control strategy modeled is one that provides a constant outdoor air flow during all
operating conditions. For CV systems, this is accomplished by maintaining a fixed outdoor air
fraction [CV(FOAF)]. However, for VAV systems, a constant outdoor airflow strategy VAV(COA)
requires that the outdoor air fraction change in inverse proportion to changes in the supply airflow.
While a VAV system with fixed outdoor air fraction control strategy [VAV(FOAF)] is common on
VAV systems, it does not maintain a constant outdoor airflow rate into the building, can result in
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significant reductions in outdoor air during part load conditions, and is not recommended (see
Project Report #2). Comparisons between 5 cfm per occupant and 20 cfm per occupant would not
be valid for VAV systems with a fixed outdoor air fraction strategy since the designated flow rates
are not maintained in these systems, VAV systems with fixed outdoor air fraction [VAV(FOAF)]
are therefore not included in this analysis.
The benefits of a temperature air-side economizer strategy is also assessed. The economizer
uses additional quantities of outdoor air to provide "free cooling" when the outdoor air temperature
is lower than the return air temperature. The quantity of outdoor air is adjusted so that the desired
supply air temperature can be achieved while using as little chiller energy as possible. To avoid
excess relative humidity indoors during the summer months, the economizer is modeled to shut off
at outdoor temperatures above 65°F. The outdoor air flow rate reverts to its base level (5 or 20
cfm per occupant) when the economizer is in the "off' mode.
A more detailed description of all the buildings and ventilation systems modeled in this project is
provided in Report #1.
APPROACH
The annual impact of raising outdoor air flow rates on energy use depends mostly on changes in
heating and cooling loads. These changes are sometimes positive and sometimes negative
depending on the seasonal variations in outdoor climate conditions. For presentation convenience
in this section, the DOE-2.1 E generated hourly air flow and energy use data were sorted into four
bins defined by significant outdoor air temperature conditions.
The first bin includes winter-like outdoor conditions (i.e., 0°F to 55°F). In general, 55°F is the
outdoor air temperature at which the outdoor air can no longer completely satisfy the cooling
requirements of the building. It is also a temperature threshold above which heating is no longer
required in the building. The second bin includes outdoor conditions in the range of 56°F to 65°F.
In this bin the total energy content of the outdoor air stream is lower than the energy content of the
return air stream. Thus, in this range the HVAC system uses 100 percent outdoor air
supplemented with mechanical cooling to meet the buildings cooling load. Above 65°F, high
humidity levels may cause the energy content of the outdoor air stream to exceed that of the return
air stream. Thus, the economizer is not used. The third bin is 66°F to 79°F. In this range, the
outdoor air will provide sensible cooling but may introduce high humidity levels causing a latent
cooling burden. The fourth bin is for outdoor temperatures in excess of 79°F. Beyond 79°F, which
is approximately the temperature of the return air, the outdoor air is expected to cause both a
sensible and a latent cooling burden.
The binned energy analysis allows for comparisons of the combined effects of outdoor air flow
rates on annual heating and cooling energy. The annual energy use data are then summarized and
converted to energy cost assuming alternative energy price structures for all climates. The price of
electricity is assumed to be $0,044 per kilowatt-hour, and $7 89 per kilowatt. The gas, which was
used for space heating and DHW service was priced at $0.49 per therm. These prices are meant
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to reflect "typical" prices based on data collected from actual utilities around the country. A
summary of the collected electric and gas utility average rates is given in Report #1.
For comparison purposes, energy costs are also computed for four additional price structures
which alter the relative price of gas and electricity, and which alter the electricity demand charge.
Unless otherwise noted, energy costs refer to costs under the base price structure. A description
of each price structure and how it was determined is also provided in Project Report #1.
RESULTS
By way of example, a binned energy framework is used to summarized results for Building A with a
CV system in the Washington, D.C. climate, and for Building A with a VAV system in Minneapolis.
Both systems are summarized with and without a temperature economizer. The purpose of this
analysis is to demonstrate how the energy impacts of increasing the outdoor air minimum flow rate
differs during alternative outdoor climate conditions and how these impacts are effected by the
operation of an economizer. Energy costs are then systematically assessed for all buildings,
ventilation systems, and climates using energy cost summary tables. A sensitivity analysis of these
results using alternative price structures is then presented.
Seasonal Impact of Increasing Outdoor Air Flow
CV System without Economizer
Exhibit 2 summarizes the seasonal energy impacts of raising outdoor air flow rates from 5 to 20
cfm per occupant for a CV system without economizer in the Washington, D.C. climate. As
expected, heating energy use increased in the winter (Bin 1) with the higher outdoor air flow rate,
while sensible cooling dropped. In the intermediate spring and fall seasons, sensible cooling
dropped in Bin 2 with no change in latent load, while latent cooling rose in Bin 3 with no change in
sensible load. In the summer (Bin 4) sensible and latent cooling energy use rose. Annually, the
building experiences a net increase in heating energy, a net decrease in sensible cooling, and a
net increase in latent cooling when the outdoor air flow rate is increased from 5 to 20 cfm per
occupant.
CV System with Economizer
The energy results for the same building with economizer is shown in Exhibit 3. Raising outdoor air
flow rates had virtually no impact on heating energy use in winter (Bin 1) and in the colder
intermediate season (Bin 2) because the economizer was already bringing in more than 20 cfm of
outdoor air per person during this period. When the economizer was off (Bins 3 and 4) the cooling
penalty (both sensible and latent) was the same as the previous case without economizer
Annually, this building experienced virtually no change in heating energy, and a modest increase in
both sensible and latent cooling energy when the outdoor air flow rate was increased from 5 to 20
cfm per occupant.
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VA V system without Economizer
Binned energy use results for this system in Minneapolis, are shown in Exhibit 4. This building
demonstrates how the added cooling benefit in the cooler months can have a substantial effect on
annual energy use. Similar to the CV system, in the winter (Bin 1) the heating energy load was
slightly increased while the cooling energy load droped significantly because of the higher outdoor
air. In the cooler conditions during the spring and fall season (Bin 2), sensible cooling fell while the
latent cooling load showed no change. As the temperature warms (Bin 3), the sensible cooling
load fell but the latent cooling load rose, until in the summer conditions (Bin 4), where both sensible
and latent cooling loads rose. Since Minneapolis experiences cool weather during a larger portion
of the year than Washington, D.C., the large winter cooling benefit tended to dominate the change
in energy use when outdoor air flow rates were raised from 5 to 20 cfm per occupant.
VA V System with Economizer
The energy results for the VAV system with an economizer are shown in Exhibit 5. Raising the
outdoor air flow rate from 5 to 20 cfm per occupant had no effect on heating energy use or cooling
energy use because the economizer was already bringing in more than 20 cfm per occupant in the
winter period. In the warmer weather when the economizer was not operating (Bins 3 and 4), this
system had the same impact as the VAV system without economizer. With the economizer, the
impact of raising the outdoor airflow rate was dominated by a modest increase in latent cooling
load. Heating and sensible cooling loads remained virtually unchanged.
Summary of Seasonal Effects
The four examples above show that the effect of increasing outdoor air flow rates in buildings has a
varying effect on heating and cooling energy use at various times of the year. In general, increased
outdoor air flow rates tended to increase winter heating energy use, though it had virtually no
impact in mild climates or in systems with economizers.
On the cooling side, increasing outdoor air flow rates tended to increase summer cooling energy
use and to decrease cooling energy use in the winter. Sensible cooling energy use was reduced
while latent energy use was increased in the spring and fall. However, in systems with
economizers, impacts of increased outdoor air flow settings are negated. This is due to the fact
that the economizer over-rides the minimum flow setting. Thus, the system does not experience an
increase in outdoor air flow when the economizer is operational. The impacts which are negated
included both an increase in heating energy use in temperate and cold climates, and a reduction in
cooling costs.
The main effect of climate is to alter the amount of time the system experiences various outdoor
temperatures, thereby changing the relative importance of the increases and decreases in energy
use described above. In any individual case, the net annual impact of increased outdoor air flow on
overall annual energy use depends on the net effect of these counteracting influences.
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While large office buildings require minimal heating energy relative to cooling energy, the analysis
demonstrates that the impact of increased outdoor air flow on heating energy costs can be as
significant as the impact on cooling energy costs. This is due to the countervailing influences on
the cooling energy costs (e.g., free cooling effect at mild temperatures which offsets the increase in
summer cooling loads) which tend to reduce the net annual impact on cooling energy..
Annual Energy Cost Impacts of Increasing Outdoor Air Flow
CV System Without Economizers
Exhibit 6 summarizes the energy cost impacts of increasing outdoor airflow rates from 5 cfm per
occupant to 20 cfm per occupant for buildings A-N with the CV(FOAF) system without economizer
in all three climates.
Raising outdoor air flow rates created a net increase in energy cost for the CV(FOAF) system in all
buildings in all climates. In the cold and temperate climates of Minneapolis and Washington, D.C.,
HVAC costs rose 2% -14%. The increase in these climates was modest because the increase in
outdoor air provided free cooling during the winter and a major part of the transition seasons.
Costs rose more (2% -18%) in the hot humid climate (Miami) because of the extended time period
of hot humid weather where the outdoor air created a substantial cooling burden. Buildings with
higher occupant densities (Buildings I and J) also experienced the greatest cost increase because
the added outdoor air is proportional to occupancy of the building.
It is interesting to note that raising outdoor airflow rates increased the net heating costs almost as
much as the net increase in cooling costs, especially in the cold climate, but also in the temperate
climate. The heating cost increase was largest for buildings with extended hours of operation
(Buildings M and N). These buildings experienced a moderate increase in their cooling costs in
the cold and temperate climate, so a net increase in overall HVAC costs was typical. However,
the building with high occupant density (building I) experienced a significant rise in both heating and
cooling costs, and this amounts to the greatest increase in overall HVAC costs among all the
building types.
VA V System Without Economizer
Exhibit 7 displays the energy cost impacts of raising outdoor air ventilation rates for VAV system
without economizer. Raising outdoor air flow rates on these systems resulted in a 0% - 9% HVAC
energy cost increase in Minneapolis, 1 % -14% increase in Washington, D.C. and an HVAC
energy cost penalty of 3% - 20% in Miami. In the Washington, D.C. and Minneapolis climates, the
VAV system had a higher basic heating requirement than the CV system because they reheat the
supply air after it is cooled. However, since the supply air temperature does not change with the
addition of higher outdoor air quantities, no change in heating costs were entailed by the higher
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outdoor air flow rates2. However, in Buildings I and J (the higher occupancy cases), the larger
quantities of outdoor air resulted in large heating energy penalties.
VAV systems also provide less supply air than CV systems under part load conditions. Thus, the
increase in outdoor air flow rates provides a greater change in the outdoor air fraction than in CV
systems during part load. Because of this higher outdoor air fraction, the VAV system without
economizer tended to experience a greater cooling energy cost reduction during the winter, spring
and fall seasons. Combined with the lack of heating penalty, the energy costs did not increase as
much as with the CV system in all three climates.
CV arid VAV Systems with Economizers
Exhibits 8 and 9 display the energy cost impact results for the CV and VAV systems with
economizers.
Overall, the systems with economizers experienced the greatest energy cost increase due to
increased minimum outdoor air flow rates. HVAC costs in both the CV and VAV systems rose 2%
- 21 %. High occupant density buildings tended to experience the largest cost increase.
The effect of raising outdoor air flow rates on systems with economizers was due almost entirely to
the increase in cooling costs. Since economizers already capture the free cooling benefit from
increased outdoor air flow, raising the minimum outdoor air flow from 5 to 20 cfm per occupant
produced a much more substantial cooling energy cost penalty than for the systems without
economizers. Raising outdoor air flow from 5 to 20 cfm per occupant produced no heating energy
cost penalty in most buildings modeled. This is due to the fact that even during much of the winter,
economizers were already bringing in at least 20 cfm per occupant of outdoor air to provide free
cooling to the building core. The one exception to this was for buildings with high occupant
densities.
SENSITIVITY OF RESULTS TO ALTERNATIVE UTILITY PRICES
In order to examine whether the conclusions were dependent on the utility price assumptions
used, the energy results were converted to energy costs using four additional utility price
structures (Exhibit 10). The justification for selecting these prices is provided in Report #1.
Exhibit 11 provides the annual HVAC costs for the base building (building A), the high
occupant density building (building I), and the building with 24 hour occupancy (building N) for
alternative price structures. Exhibit 11 demonstrates the dominance of electric energy over
gas energy on HVAC energy costs. For any given HVAC system, going from the base price
or from the high gas/low electricity price option to the low gas/high electricity price option
2 The only exception to this Is high occupant density building where higher outdoor airflow rates require a high
outdoor air fraction and a preheat requirement in cold weatherto avoid coil freezing. This occurs in Minneapolis,
and to a lesser extent in Washington, D,C.
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significantly raised HVAC energy costs. Likewise, high (or low) demand charges can play a
significant role in raising (or lowering) HVAC energy costs.
Exhibit 11 also demonstrates the importance of the price structure in assessing the impact of
choosing between HVAC system options. For example, under the low gas/high electricity
price option, the economizer systems were much more attractive than on the base price or the
high gas/low electricity price options. In fact, because of the heating penalty associated with
the CV system economizer that was modeled, high gas prices and low electricity prices
resulted in higher HVAC costs (rather than lower costs) from the use of an economizer on that
CV system.
Exhibit 12, however, demonstrates that alternative price structures, in general, have little
impact on the percentage cost increase associated with raising outdoor air flow rates. The
main exception appears to be in the cold climate (Minneapolis) where raising outdoor airflow
rates would result in a substantial heating penalty. Thus, raising outdoor air flow rates can be
unusually expensive in cold climates when gas prices are high relative to electricity prices.
Exhibit 12 also demonstrates that under particular building, climate and utility pricing
conditions, raising outdoor air supply may oddly reduce energy costs in unique circumstances.
SUMMARY
Heating Energy Costs
Raising outdoor air flow rates in commercial office space resulted in heating and cooling
energy use changes, some resulting in increased cost, and some resulting in decreased cost.
In general, heating costs increased in the CV system without economizer in temperate to cold
climates. The increase is most dramatic for buildings with high occupant density and
buildings that operate 24 hours a day. Otherwise, heating cost impacts tended to be
inconsequential.
Cooling Energy Cost
Cooling costs can either increase or decrease when outdoor airflow rates are increased.
Raising minimum outdoor air flow rates in cooler weather tended to act as an economizer and
provide free cooling. Raising minimum outdoor air flow rates in systems that already had
economizers had no effect during cooler weather when the economizer was operating.
Raising outdoor airflow rates in the summer always increased the cooling energy costs. The
annual effect on cooling energy cost depends on the proportion of the year in which the
outdoor climate is cold, temperate or hot/humid. The economizer has little effect in hot humid
climates because only a small portion of the year is available for economizing.
The VAV system without economizer experienced an annual decrease in cooling energy costs
in cold and temperate climates, and an annual increase in hot humid climates. The VAV
system with economizer always experienced an annual increase in cooling energy costs. The
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CV system without economizer in cold climates was most apt to experience a decrease in
annual cooling energy costs, but this is not substantial except for buildings that operate 24
hours a day.
Building Characteristics
Of all the building characteristics studied, occupant density and to a lesser extent, hours of
operation had the most profound effect on the energy cost impact of increasing outdoor air
flow rates. When heating or cooling energy costs increase because of increased coil loads,
these increases were magnified as occupant density rose, or to a less extent, as hours of
operation were extended to 24 hours a day.
Annual Energy Cost Impact
For the base building, modeled, raising outdoor airflow rates from 5 to 20 cfm per occupant
had modest effects on annual energy costs ranging from annual HVAC energy cost increase
of 2% -10% ( or an increase of total energy cost of approximately 1 % to 4%) under base
price conditions. Above this range are buildings with high occupant density. For example, the
very high occupant density building (Building I) experienced HVAC cost increases of 9%-21 %
(approximately 4%-8% increase in total energy) under base price conditions. When
alternative pricing structures are applied, the range of energy cost increases widened
somewhat, ranging from 0% -12% for HVAC energy (or approximately 0% to 5% total energy)
for the base building, while for the high occupant density building the HVAC energy cost
increase ranged from 8% to 24% (or approximately 4% to 10% for total energy) under
alternative pricing structures.
The sensitivity of energy cost impacts to high occupant density situations has important
implications. In this report, high occupant density is defined as 15 occupants per 1000 square
feet. These densities are modest when compared to education buildings, auditoriums,
theaters, and similar facilities where occupant densities can be 5 to 10 times that level. It
raises special issues about the feasibility of maintaining adequate indoor air quality in these
buildings by using the outdoor air ventilation rates recommended in ASHRAE Standard 62-
1999. Because of this implication, this issue is addressed separately in detail in a
companion report (Project Report #6).
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BIBLIOGRAPHY
ASHRAE, 1999. ASHRAE Standard 62-1999: Ventilation for Acceptable Indoor Air Quality,
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta.
Cowan, J. 1986. "Implications of Providing Required Outside Air Quantities in Office
Buildings." ASHRAE Transactions V. Pt. Atlanta.
Curtis, R., Birdsall, B., Buhl, W., Erdem, E., Eto, J., Hirsch, J., Olson, K., and Winkelmann, F.
1984. DOE-2 Building Energy Use Analysis Program. LBL-18046. Lawrence Berkeley
Laboratory.
Eto, J., and Meyer, C. 1988. "The HVAC Costs of Fresh Air Ventilation in Office Buildings."
ASHRAE Transactions. V. 94. Pt.2.
Eto, J. 1990. "The HVAC Costs of Increased Fresh Air Ventilation Rates in Office Buildings,
Part 2." In Proceeding, of indoor Air 90: The Fifth International Conference on Indoor Air
Quality and Climate. Toronto, Canada.
Janu G., Wenger, J., and Nesler.C. 1985. Outdoor Air Flow Control for VAV Systems.
ASHRAE Journal. April.
Levenhagen, J. 1992. "Control Systems to Comply with ASHRAE Standard 62-1989."
ASHRAE Journal. Atlanta, September
Mutammara, A., and Hittle, D. 1990. "Energy Effects of Various Control Strategies for
Variable Air Volume Systems." ASHRAE Transactions. V. 96. Pt. 1. Atlanta.
Sauer, H., and Howell, R., 1992. "Estimating the Indoor Air Quality and Energy Performance
of VAV Systems." ASHRAE Journal. Atlanta. July.
Solberg, D., Dougan, D., and Damiano L. 1990. Measurement for the Control of Fresh Air
Intake. ASHRAE Journal. January.
Steele,T.. and Brown, M. 1990. Energy and Cost Implications of ASHRAE Standard 62-
1989. Bonnyville Power Administration. May.
Ventresca, J. 1991. Operation and Maintenance for IAQ: Implications from Energy Simulation
of Increased Ventilation. Proc. Of IAQ'91: Healthy Buildings. Washington, D C. American
Society of Heating, Refrigerating and Air-Conditioning Engineers. Atlanta.
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Exhibit 1: Building and HVAC Characteristics
Building Configuration
Window
R-Value
Window
Shading
Coeffic.
Roof
Insulation
Infiltration
Rate
Chiller
COP
Boiler
Effic.
(%)
Occup.
Density
(Occup/
1000 SF)
P/C
Ratio
Exhaust
Flow
Rate
(cfm)
Daily
Operating
Hours
(hrs/day)
A. Base Case
2.0
0.8
10
0.5
3.5
70
7
0.5
750
12
B. High Effic. Shell
3.0
0.6
20
0.75
3.5
70
7
0.5
750
12
C. Low Effic. Shell
1.0
1.0
5
0.25
3.5
70
7
0.5
750
12
D. High Effic. HVAC
System
2.0
0.8
10
0.5
4.5
80
7
0.5
750
12
E. Low Effic. HVAC
System
2.0
0.8
10
0.5
2.5
60
7
0.5
750
12
F. High P/C Ratio
2.0
0.8
10
0.5
3.5
70
7
0.8
750
12
G. Low P/C Ratio
2.0
0.8
10
0.5
3.5
70
7
0.3
750
12
H. High Exhaust Rate
2.0
0.8
10
0.5
3.5
70
7
0.5
1500
12
I. High Occup. Density
2.0
0.8
10
0.5
3.5
70
15
0.5
750
12
J. Medium Occup.
Density
2.0
0.8
10
0.5
3.5
70
10
0.5
750
12
K. Low Occup. Density
2.0
0.8
10
0.5
3.5
70
5
0.5
750
12
L. Very Low Occup.
Density
2.0
0.8
10
0.5
3.5
70
3
0.5
750
12
M. Extended Oper. Hours
2.0
0.8
10
0.5
3.5
70
7
0.5
750
18
N. 24 Hour Operation
2.0
0.8
10
0.5
3.5
70
7
0.5
750
24
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Exhibit 2
Change in Coil Loads with increased Outdoor Air Flow Rate for Building
A with CV (FOAF) in Washington, DC
2500 i					
2000 --
1500 --
^ 1000
3
¦1000
-2000 --
-2500 -L
Bin1 (<55°F) Bin2 (56-65°F) Biri3 (66-79°F) Bin4 (>80°F)	Annual
Outdoor Air Temperature (°F)
B Heating
El Cooling (S)
B Cooling (L)
Exhibit 3
Change in Coil Loads with Increased Outdoor Air Flow Rate for Building
A with CV (FOAF) EconT in Washington, DC
2500	|
2000	j
1500	+ !
_ 1000
=J
§i 500
= -500
O
° -1000
-1500
-2000
-2500 -L	1
Bin1 (<55°F) Biri2 (55-65°F) Bin3 (66-73°F) Bin4 (>80°F)
Outdoor Air Temperature (°F)

.Jil
Annual 0 Heating 0
[SCooling (S)
[HCooling (L)

-------
Exhibit 4
Change in Coil Loads with increased Outdoor Air Flow Rate for Building
A with VAV (COA) in Minneapolis, MN
2500
2000
1500 --
„ 1000
3
| 500 --
I 0
o
O
-500
-1000
-1500
-2000
-2500


Bin1 (<55°F) Bin2 (56-65° F) Bin3 (66-79°F) Bin4 (>80°F)
Outdoor Air Temperature (°F)
H
Annual
] Heating
QCooling (S)
0 Cooling (L)
Exhibit 5
Change in Coil Loads with Increased Outdoor Air Flow Rate for Building
A with VAV (COA) Eeonjin Minneapolis, MN
2500
3
m
E
¦D
10
o
o
o
2000
1500
1000
500
0
-500
-1000
-1500
-2000
-2500

Jul
Bin1 (<55°F) Bm2 (56-65°F) Bin3 (66-79°F) Bin4 (>80°F)
Outdoor Air Temperature (°F)
Annual
H Heating
H Cooling (S)
IS Cooling (L)

-------
Exhibit 6
Comparison of Annual HVAC Energy Costs for Outdoor Air Flow Rates of 5 and 20
cfm per Occupant: CV Systems without Economizers

Minneapolis,
MN
Washington, DC


Miami, FL

Building Configuration
Cooling
Heating
Total
Cooling
Heating
Total
Cooling
Heating
Total

<$/sf)
($/sfi
(S/sf)
($/sf)
iS/sf)
($/sf)
($/sf)
(S.'sf)
($/sf)
A. Base Case @5
0.49
0,02
0.83
0.51
0.00
0,81
0.63
0.00
0.94
Increase
0.03
0.02
0.05
0.05
0.01
0.06
0.08

0.08
Percent Increase
6%
83%
6%
9%
156%
7%
13%
None
9%
B. High Eff, Shell @5
0,46
0.01
0.73
0.48
0.00
0.73
0.59
0.00
0.87
Increase
0.02
0.01
0.04
0,04

0.05
0.08

0.08
Percent Increase
5%
141%
5%
9%
None
6%
14%
None
9%
C, Low Eff. Shell @5
0.52
0.07
0.96
0,55
0.02
0.93
0.69
0.00
1.02
Increase
0.04
0.03
0.06
0.06
0.01
0.07
0.08

0,08
Percent Increase
7%
38%
7%
11%
72%
8%
12%
None
8%
D. High Eff. HVAC @5
0.37
0.02
0.71
0.39
0.00
0.68
0.48
0.00
0.78
Increase
0.02
0.02
0.04
0.04
0.01
0.04
0.06

0.06
Percent Increase
6%
83%
6%
10%
156%
6%
13%
None
8%
E. Low Eff. HVAC @5
0.70
0.03
1.05
0.73
0.01
1.03
0.91
0.00
1.21
Increase
0.05
0.02
0.07
0.07
0.01
0.08
0.12

0,12
Percent Increase
7%
83%
7%
10%
156%
8%
13%
None
10%
F. High P/C Ratio @5
0.53
0,04
0.93
0.56
0.01
0.89
0.69
0.00
1.03
Increase
0.04
0.02
0.06
0.05
0.01
0.05
0.08

0.08
Percent Increase
4%
45%
4%
7%
69%
5%
9%
None
6%
G. Low P/C Ratio @5
0.44
0,01
0.72
0.47
0.00
0.72
0.56
0.00
0.82
Increase
0.03
0.02
0.04
0.04
0.01
0.05
0.09

0.09
Percent Increase
6%
140%
6%
9%
250%
6%
16%
None
11%
H. High Exhaust @5
0,50
0.03
0.86
0.52
0.01
0.83
0.66
0.00
0.97
Increase
0.02
0,01
0.04
0.04
0.01
0.04
0.06

0.06
Percent Increase
4%
50%
4%
7%
102%
5%
9%
None
6%
1. High Occ. Dens. @5
0.54
0.03
0,91
0.60
0.00
0.99
0.72
0.00
1.05
Increase
0,07
0.05
0.13
0.10
0,02
0.11
0.19

0.19
Percent Increase
14%
199%
14%
17%
408%
11%
27%
None
18%
J. Medium Occ. Dens. @5
0.51
0.02
0,86
0.54
0,01
0.84
0.66
0.00
0.98
Increase
0.05
0.03
0.08
0.07
0.01
0,08
0.13

0.13
Percent Increase
10%
129%
10%
13%
226%
10%
19%
None
13%
K. Low Occ. Dens. @5
0,48
0.03
0.81
0.50
0.01
0.79
0.62
0.00
0.92
Increase
0.02
0,01
0.04
0.03

0.03
0.05

0.05
Percent Increase
4%
51%
4%
6%
None
4%
8%
None
6%
L. Very Low Occ. Dens. @5
0.46
0.03
0.79
0.49
0.01
0.78
0.60
0.00
0.90
Increase
0.01
0.01
0.01
0.01

0.01
0.02

0.02
Percent Increase
2%
19%
2%
2%
None
2%
3%
None
2%
M. Extended Op. Hours @5
0.50
0.04
0.88
0,53
0.01
0.86
0.65
0.00
0.97
Increase
0,02
0.03
0.06
0.04
0.02
0.05
0.09

0.09
Percent Increase
5%
81%
7%
7%
117%
6%
15%
None
10%
N, 24 Hour Operation @5
0.52
0.06
0.96
0.55
0.02
0.94
0.69
0.00
1.07
Increase
0.01
0,06
0.07
0.03
0.03
0.06
0.10

0.10
Percent Increase
2%
91%
7%
5%
128%
6%
15%
None
10%
Energy Cost and IAQ
15
Report # 4

-------
Exhibit 7
Comparison of Annual HVAC Energy Costs for Outdoor Air Flow Rates of 5 and 20
cfm per Occupant: VAV Systems without Economizers

Minneapolis,
MN
Washington, DC


Miami, FL

Building Configuration
Cooling
Heating
Total
Cooling
Heating
Total
Cooling
Heating
Total

<$/sf)
($/sfi
(S/sf)
($/sf)
iS/sf)
($/sf)
($/sf)
(S.'sf)
($/sf)
A. Base Case @5
0.48
0,10
0.77
0.49
0.05
0.71
0.57
0.00
0.76
Increase
0.01

0.02
0.03

0.03
0.07

0.07
Percent Increase
3%
None
2%
6%
None
4%
13%
None
10%
B. High Eff, Shell @5
0.44
0.05
0.64
0.45
0,02
0.62
0.54
0.00
0.71
Increase
0.01

0.01
0,03

0.03
0.08

0.08
Percent Increase
2%
None
2%
7%
None
5%
14%
None
11%
C, Low Eff. Shell @5
0.51
0.20
0.92
0.54
0.11
0.85
0.62
0.01
0.82
Increase
0.01

0.02
0.03

0.04
0,07

0,07
Percent Increase
3%
None
2%
6%
None
4%
11%
None
8%
D. High Eff. HVAC @5
0.36
0.09
0.64
0.37
0.04
0.59
0.43
0.00
0.62
Increase
0.01

0.01
0.02

0.02
0.06

0.06
Percent Increase
3%
None
2%
6%
None
4%
13%
None
9%
E. Low Eff. HVAC @5
0.68
0.12
0.99
0.70
0.06
0.93
0.82
0.00
1.01
Increase
0.02

0.02
0.05

0-05
0.11

0.11
Percent Increase
3%
None
2%
7%
None
5%
13%
None
11%
F. High P/C Ratio @5
0.52
0.14
0.86
0.53
0.07
0.79
0.62
0.00
0.82
Increase
0.01

0.02
0.03

0.03
0.07

0.07
Percent Increase
2%
None
2%
4%
None
3%
9%
None
7%
G. Low P/C Ratio @5
0.42
0,06
0.65
0.44
0.03
0.62
0.52
0.00
0.68
Increase
0.01

0.02
0.03

0.03
0.08

0.08
Percent Increase
3%
None
2%
7%
None
5%
15%
None
12%
H. High Exhaust @5
0,48
0.10
0.78
0.50
0.05
0.73
0.60
0.00
0.79
Increase
0.01

0-01
0.02

0.02
0.05

0.05
Percent Increase
2%
None
2%
5%
None
3%
9%
None
7%
1. High Occ. Dens. @5
0.52
0,10
0,82
0.56
0,06
0.83
0.65
0.00
0.84
Increase
0,04
0,03
0.07
0.08
0,01
0.11
0.17

0.17
Percent Increase
8%
31%
9%
14%
23%
14%
26%
None
20%
J. Medium Occ. Dens. @5
0.49
0,10
0,79
0.51
0,05
0.74
0.60
0.00
0.79
Increase
0.02
0.01
0.03
0.04

0,04
0.11

0.11
Percent Increase
5%
8%
4%
8%
None
6%
19%
None
15%
K. Low Occ. Dens. @5
0,46
0.10
0.74
0.48
0,05
0.70
0.56
0.00
0.74
Increase
0.01

0-01
0.02

0.02
0.05

0.05
Percent Increase
2%
None
1%
4%
None
3%
8%
None
6%
L. Very Low Occ. Dens. @5
0.45
0,10
0.72
0.47
0.05
0-69
0.55
0.00
0.72
Increase



0.01

0.01
0.02

0.02
Percent Increase
None
None
None
2%
None
1%
3%
None
3%
M. Extended Op. Hours @5
0.49
0,15
0.84
0,51
0.09
0.79
0.60
0.02
0.81
Increase

0.01
0.01
0.02

0.02
0.07

0.07
Percent Increase
None
5%
1%
4%
None
3%
12%
None
9%
N, 24 Hour Operation @5
0.51
0.20
0.94
0.54
0.14
0.90
0.64
0.05
0.91
Increase
-0.02
0,01

0.01

0.01
0.08

0.08
Percent Increase
-4%
7%
None
2%
None
2%
13%
None
9%
Energy Cost and IAQ
16
Report # 4

-------
Exhibit 8
Comparison of Annual HVAC Energy Costs for Outdoor Air Flow Rates of 5 and 20
cfm per Occupant: CV Systems with Economizers

Minneapolis,
MN
Washington, DC


Miami, FL

Building Configuration
Cooling
Heating
Total
Cooling
Heating
Total
Cooling
Heating
Total

<$/sf)
($/sfi
(S/sf)
($/sf)
iS/sf)
($/sf)
($/sf)
(S.'sf)
($/sf)
A. Base Case @5
0.40
0,10
0.82
0.43
0.06
0,79
0.62
0.00
0.93
Increase
0.05

0.05
0.07

0.06
0.09

0.08
Percent Increase
13%
None
7%
15%
None
8%
14%
None
9%
B. High Eff, Shell @5
0.36
0.07
0.69
0.40
0,04
0.69
0.58
0.00
0.85
Increase
0.05
0.01
0.05
0,06

0.06
0.09

0.08
Percent Increase
13%
7%
8%
16%
None
9%
15%
None
10%
C, Low Eff. Shell @5
0.44
0.15
0.97
0.48
0.09
0.93
0.68
0.01
1.02
Increase
0.05

0.06
0.07

0.07
0.08

0,08
Percent Increase
12%
None
6%
15%
None
8%
12%
None
8%
D. High Eff. HVAC @5
0.30
0.09
0.71
0.33
0.06
0.67
0.47
0.00
0.78
Increase
0.04

0.04
0.05

0.05
0.06

0.06
Percent Increase
13%
None
6%
15%
None
7%
14%
None
8%
E. Low Eff. HVAC @5
0.58
0.12
1.01
0.62
0.07
0.98
0.89
0.01
1.20
Increase
0.07

0.08
0.10

0.09
0.12

0,12
Percent Increase
13%
None
8%
16%
None
10%
14%
None
10%
F. High P/C Ratio @5
0.44
0,13
0.93
0.48
0.08
0.89
0.68
0.01
1.02
Increase
0.05

0.05
0.06

0.06
0.08

0.08
Percent Increase
9%
None
4%
11%
None
6%
9%
None
6%
G. Low P/C Ratio @5
0.35
0,06
0.68
0.39
0.04
0.68
0.55
0.00
0.82
Increase
0.05

0.06
0.06

0.06
0.09

0.09
Percent Increase
15%
None
8%
15%
None
9%
16%
None
11%
H. High Exhaust @5
0,42
0.10
0.84
0.45
0.06
0.81
0.65
0.00
0.96
Increase
0.04

0-04
0.05

0.05
0.06

0.06
Percent Increase
8%
None
4%
11%
None
6%
10%
None
6%
1. High Occ. Dens. @5
0.45
0,10
0,89
0.51
0,05
0.94
0.70
0.00
1.04
Increase
0,11
0,02
0.13
0.13

0.13
0.19

0.19
Percent Increase
25%
19%
15%
26%
None
14%
28%
None
18%
J. Medium Occ. Dens. @5
0.42
0,10
0,84
0.46
0,06
0.82
0.65
0.00
0.97
Increase
0.08
0.01
0.08
0.09

0,09
0.13

0.13
Percent Increase
19%
6%
10%
20%
None
11%
20%
None
13%
K. Low Occ. Dens. @5
0,39
0.10
0.79
0.43
0,06
0.78
0.61
0.00
0.91
Increase
0.03

0.04
0.04

0.04
0.05

0.05
Percent Increase
9%
None
5%
9%
None
5%
9%
None
6%
L. Very Low Occ. Dens. @5
0.38
0.09
0.77
0.42
0.06
0.76
0.59
0.00
0.90
Increase
0.01

0.02
0.02

0.02
0.02

0.02
Percent Increase
4%
None
2%
4%
None
2%
3%
None
2%
M. Extended Op. Hours @5
0.38
0.14
0.85
0,42
0.09
0.83
0.63
0.01
0.96
Increase
0,05
0.01
0.06
0.06

0.06
0.10

0.10
Percent Increase
14%
7%
7%
14%
None
8%
15%
None
10%
N, 24 Hour Operation @5
0.36
0.19
0.93
0.41
0.11
0.89
0.66
0.01
1.05
Increase
0.05
0,02
0.07
0.06
0.01
0.07
0.10

0.10
Percent Increase
13%
12%
8%
14%
12%
8%
16%
None
10%
Energy Cost and IAQ
17
Report # 4

-------
Exhibit 9
Comparison of Annual HVAC Energy Costs for Outdoor Air Flow Rates of 5 and 20
cfm per Occupant: VAV System with Economizer

Minneapolis,
MN
Washington, DC


Miami, FL

Building Configuration
Cooling
Heating
Total
Cooling
Heating
Total
Cooling
Heating
Total

<$/sf)
($/sfi
(S/sf)
($/sf)
iS/sf)
($/sf)
($/sf)
(S.'sf)
($/sf)
A. Base Case @5
0.39
0,10
0.69
0.42
0.05
0,65
0.57
0.00
0.75
Increase
0.04

0.04
0.05

0.05
0.07

0.08
Percent Increase
10%
None
6%
12%
None
8%
13%
None
10%
B. High Eff, Shell @5
0.36
0.05
0.57
0.39
0,02
0.56
0.53
0.00
0.70
Increase
0.04

0.04
0,05

0.06
0.08

0.08
Percent Increase
11%
None
7%
14%
None
10%
15%
None
11%
C, Low Eff. Shell @5
0.43
0.20
0.84
0.47
0.12
0.79
0.61
0.01
0.81
Increase
0.04

0.04
0.05

0.05
0.07

0,07
Percent Increase
9%
None
5%
11%
None
7%
11%
None
9%
D. High Eff. HVAC @5
0.30
0.09
0.58
0.32
0.04
0,54
0.43
0.00
0.61
Increase
0.03

0.03
0.04

0.04
0.06

0.06
Percent Increase
10%
None
5%
12%
None
7%
13%
None
9%
E. Low Eff. HVAC @5
0.57
0.12
0.88
0.61
0.06
0.84
0.82
0.00
1.00
Increase
0.06

0.06
0.07

0.08
0.11

0,11
Percent Increase
10%
None
7%
12%
None
9%
13%
None
11%
F. High P/C Ratio @5
0.43
0,14
0.79
0.47
0.07
0.73
0.62
0.00
0.82
Increase
0.04

0.04
0.05

0.05
0.07

0.07
Percent Increase
7%
None
4%
8%
None
5%
9%
None
7%
G. Low P/C Ratio @5
0.35
0,07
0.57
0.38
0.03
0.56
0.51
0.00
0.67
Increase
0.04

0.04
0.05

0.05
0.08

0.08
Percent Increase
11%
None
7%
13%
None
9%
15%
None
12%
H. High Exhaust @5
0,41
0.10
0.71
0.44
0.05
0.67
0.59
0.00
0.78
Increase
0.03

0.03
0.04

0.04
0.05

0.05
Percent Increase
7%
None
4%
9%
None
6%
9%
None
7%
1. High Occ. Dens. @5
0.44
0,10
0,75
0.50
0,06
0.76
0.64
0.00
0.84
Increase
0,09
0,03
0.12
0.11
0,01
0.14
0.17

0.17
Percent Increase
20%
26%
16%
22%
21%
19%
27%
None
21%
J. Medium Occ. Dens. @5
0.41
0,10
0,71
0.45
0,05
0.68
0.59
0.00
0.78
Increase
0.06
0.01
0.07
0.07

0,07
0.12

0.12
Percent Increase
15%
6%
9%
15%
None
10%
19%
None
15%
K. Low Occ. Dens. @5
0,38
0.10
0.66
0.42
0,05
0.64
0.55
0.00
0.73
Increase
0.03

0.03
0.03

0.03
0.05

0.05
Percent Increase
7%
None
4%
7%
None
5%
8%
None
6%
L. Very Low Occ. Dens. @5
0.37
0.10
0.65
0.41
0.05
0.63
0.54
0.00
0.72
Increase
0.01

0.01
0.01

0.01
0.02

0.02
Percent Increase
3%
None
2%
3%
None
2%
3%
None
3%
M. Extended Op. Hours @5
0.38
0.15
0.73
0,42
0.09
0.70
0.59
0.02
0.80
Increase
0,04

0.04
0.05

0.05
0.07

0.08
Percent Increase
10%
None
6%
11%
None
7%
13%
None
9%
N, 24 Hour Operation @5
0.36
0.22
0.80
0.41
0.15
0.78
0.62
0.05
0.89
Increase
0.04
0,01
0.05
0.05

0.05
0.09

0.09
Percent Increase
11%
4%
6%
12%
None
6%
14%
None
10%
Energy Cost and IAQ
18
Report # 4

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Exhibit 10
Alternative Utility Rate Structures

Rate Class
Rate Structure
Rate
Gas
Electric
Electric
Gas
Electric
Electric
Ratchet
Structures
Rate
Rate
Demand
Rate
Rate
Demand
Clause
Base
Average
Average
Average
$0,490
$0,044
$7,890
No
1
Low
High
Average
$0,330
$0,063
$7,890
No
2
High
Low
Average
$0,650
$0,025
$7,890
No
3
Average
Average
High
$0,490
$0,044
$11,710
No
4
Average
Average
Low
$0,490
$0,044
$4,070
No
Energy Cost and IAQ
19
Report # 4

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Exhibit 11
Comparison of Annual HVAC Energy Costs Under Alternate Price Structures
With Outdoor Air at 20 cfm per occupant
HVAC System
Minneapolis, MN
Washington, DC
Miami, FL

Base
Lo Gas
Hi Gas
Hi
Lo
Base
Lo Gas
Hi Gas
Hi
Lo
Base
Lo Gas
Hi Gas
Hi
Lo
Building

Hi Elc
Lo Elc
Dmd
Dmd

Hi Elc
Lo Elc
Dmd
Dmd

Hi Elc
Lo Elc
Dmd
Dmd

$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
CV(FOAF)















A
0.88
1.08
0.69
1.05
0.72
0.86
1.07
0.65
1.03
0.69
1.02
1.30
0.74
1.20
0.84
I
1.04
1.24
0.83
1.25
0.83
1.10
1.36
0.84
1.33
0.87
1.24
1.56
0.91
1.47
1.00
N
1.03
1.24
0.82
1.19
0.87
1.00
1.25
0.75
1.17
0.84
1.17
1.53
0.82
1.35
1.00
VAV/COA















A
0.78
0.91
0.66
0.93
0.63
0.74
0.89
0.60
0.90
0.59
0.83
1.04
0.62
0.99
0.67
I
0.89
1.02
0.77
1.08
0.71
0.94
1.12
0.77
1.14
0.74
1.01
1.26
0.77
1.23
0.80
N
0.94
1.05
0.83
1.08
0.79
0.92
1.07
0.76
1.06
0.77
0.99
1.24
0.73
1.14
0.84
CV(FOAF)/Econt















A
0.87
1.02
0.72
1.04
0.71
0.85
1.02
0.68
1.02
0.68
1.01
1.29
0.74
1.19
0.84
I
1.02
1.19
0.85
1.23
0.82
1.07
1.30
0.85
1.30
0.85
1.23
1.55
0.91
1.46
1.00
N
1.00
1.13
0.87
1.16
0.84
0.96
1.14
0.79
1.13
0.80
1.16
1.49
0.82
1.33
0.99
VAV/COA/Econ
T















A
0.73
0.83
0.63
0.88
0.58
0.70
0.82
0.57
0.85
0.54
0.83
1.04
0.62
0.99
0.66
I
0.86
0.97
0.75
1.05
0.68
0.91
1.06
0.75
1.11
0.70
1.01
1.25
0.77
1.22
0.80
N
0.84
0.91
0.78
0.99
0.70
0.83
0.95
0.72
0.98
0.68
0.98
1.23
0.73
1.13
0.83
Energy Cost and IAQ
Report # 4

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Exhibit 12
Comparison of Percent Increase in Annual HVAC Energy Costs when Increasing Outdoor Air Flow Rates from 5 to 20 cfm per
Occupant under Alternate Price Structures

Minneaplis, MN

Washington,
DC

Miami, FL
HVAC System

Lo Gas
Hi Gas
Hi
Lo

Lo Gas
Hi Gas
Hi
Lo

Lo Gas
Hi Gas
Hi
Lo
Building
Base
Hi Elec
Lo Elec
Demand
Demand
Base
Hi Elec
Lo Elec
Demand
Demand
Base
Hi Elec
Lo Elec
Demand
Demand

$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
$/sf
CV(FOAF)















A
6%
4%
10%
7%
5%
7%
5%
10%
8%
5%
9%
8%
11%
10%
7%
I
14%
9%
21%
15%
12%
11%
9%
16%
14%
8%
18%
16%
21%
20%
15%
N
7%
3%
13%
8%
6%
6%
4%
10%
7%
5%
10%
9%
10%
10%
9%
VAV/COA















A
2%
1%
4%
4%
0%
4%
3%
7%
6%
2%
10%
9%
12%
11%
8%
I
9%
5%
14%
11%
5%
14%
11%
17%
16%
10%
20%
18%
24%
23%
17%
N
0%
-3%
3%
1%
-2%
2%
0%
4%
3%
0%
9%
8%
10%
10%
8%
CV(FOAF)EconT















A
7%
6%
7%
7%
5%
8%
8%
9%
9%
6%
9%
8%
11%
10%
8%
I
15%
13%
17%
16%
13%
14%
12%
16%
16%
11%
18%
16%
21%
20%
15%
N
8%
6%
9%
8%
7%
8%
7%
10%
9%
7%
10%
10%
11%
10%
9%
VAV(COA)EconT















A
6%
5%
7%
7%
4%
8%
7%
9%
9%
6%
10%
9%
12%
11%
8%
I
16%
14%
19%
17%
14%
19%
17%
21%
20%
16%
21%
19%
24%
23%
17%
N
6%
6%
7%
7%
5%
6%
6%
7%
7%
5%
10%
9%
10%
10%
8%

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