FINAL REPORT
Formaldehyde Exposure Model -
Description and Demonstration
EPA Contract No. 68-02-3968
Task 110
Prepared for:
U.S. Environmental Protection Agency
Exposure Evaluation Division
Office of Toxic Substances
401 M Street, S.W.
Washington, D.C. 20460
Prepared by:
Versar Inc
6850 Versar Center
Springfield, Virginia 22151
April 18, 1986
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Pi sclaimer
Although this report has been funded by the United States
Environmental Protection Agency through Contract No. 68-02-3968 to Versar
Inc., it has not been subjected to the Agency's peer and policy review
and therefore does not necessarily reflect the views of the Agency; no
official endorsement should be inferred.
i i
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Acknowledgements
This project was funded by the U.S. Environmental Protection Agency,
Office of Toxic Substances, Exposure Evaluation Division, Exposure
Assessment Branch. This report was prepared by Versar Inc. of
Springfield, Virginia, in response to EPA Work Orders 14 and 110 of
Contract No. 68-02-3968.
The EPA Project Manager for this effort was Michael Callahan and the
EPA Task Manager was Greg Schweer; their support and direction is
gratefully acknoweldged.
A number of Versar personnel have contributed to this task over the
period of performance as shown below:
Program Management - Gayaneh Contos
Task Management - Cindy Lewis,
Gina Dixon
Technical Support
Secretarial/Clerical
- Tom Chambers,
Shiv Kri shnan,
Jim Edmi ston,¦and
DeDe Gamgoum
- Shir1ey Harri son,
Franklin Clay,
Sue Elhussein, and
Ann Hunt
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TABLE OF CONTENTS
Page No.
1. INTRODUCTION 1
1.1 Background 1
1.2 Report Organization 3
1.3 Summary of Model Run Results 3
2. MODEL DESCRIPTION 6
2.1 Initial Formaldehyde Concentration (Component 1) 7
2.1.1 Iterative Computation Loop Solution 11
2.1.2 Matthews et al. Simple Steady-State Model for
Indoor Formaldehyde Concentrations 12
2.1.3 HBF Simple Steady-State Model for Indoor
Formaldehyde Concentrations 16
2.2 Decay Curve Function (Component 2) 17
2.3 Capabilities and Limitations of the Model 20
3. MODEL INPUT REQUIREMENTS 23
3.1 Home Dimensions 23
3.2 Pressed Wood Product Loadings 23
3.3 Emission Rate Input 24
3.4 Background Formaldehyde Levels 30
3.5 Other Parameters 30
4. ANALYSES AND CONCLUSIONS 33
4.1 Comparison of Models 33
4.2 Effect of Formaldehyde Emission Rates 37
4.3 Effect of Product Loading 37
4.4 Effect of Air Exchange Rates 37
5. REFERENCES 46
APPENDIX A COMPUTER PROGRAM FOR VERSAR MODEL A-l
APPENDIX B NAHB BUILDER PRACTICES SURVEY RESULTS B-l
APPENDIX C DETAILED CALCULATIONS ON WOOD PRODUCTS REQUIREMENTS
FOR CABINETS AND DOORS IN MANUFACTURED HOMES C-l
APPENDIX D METHODOLOGY FOR CALCULATION OF WOOD PRODUCT USE IN
CABINETS IN SINGLE FAMILY DETACHED AND ATTACHED HOMES D-l
i v
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LIST OF TABLES
Page No.
Table 1. Summary Table for Formaldehyde Model Runs 4
Table 2. Linear Formaldehyde Emission Models Based on
Environmental Chamber Data Taken at 23°C, 501 RH .... 9
Table 3. UF Pressed Wood Product Loadings in Homes Containing
These Products 25
Table 4. Predicted Chamber Concentrations at HUD Test
Conditions 27
Table 5. Summary of 1985 NPA HUD Certification Test Results .. 28
Table 6. Frequency Distribution of June 1984 - Late June 1985
Chamber Test Data for Hardwood Plywood 29
Table 7. Selected Product Emission Profiles 31
Table 8. Formaldehyde Levels Contributed by Other Sources — 32
Table 9. Model Runs Sorted in Descending Order of
Exposure Value 34
V
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LIST OF FIGURES
Page No.
Figure 1. Plot of Combined Data Set 19
Figure 2. Comparison of Initial Formaldehyde Levels Predicted
By Three Models 36
Figure 3. Effects of Emission Profile on Initial and Mean
Formaldehyde Levels in Manufactured, Detached, and
Attached Homes 38
Figure 4. Effect of Product Loading on Predicted Initial and
Mean Formaldehyde Levels in Manufactured Homes 39
Figure 5. Effect of Product Loading on Predicted Initial and
Mean Formaldehyde Levels in Detached Homes 40
Figure 6. Effect of Product Loading on Predicted Initial and
Mean Formaldehyde Levels in Attached Homes 41
Figure 7. Effect of Air Exchange Rate on Predicted Initial
and Mean Formaldehyde Levels in Manufactured Homes .. 42
Figure 8. Effect of Air Exchange Rate on Predicted Initial
and Mean Formaldehyde Levels in Detached Homes 43
Figure 9. Effect of Air Exchange Rate on Predicted Initial
and Mean Formaldehyde Levels in Attached Homes 44
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FORMALDEHYDE EXPOSURE MODEL -
DESCRIPTION AND DEMONSTRATION
1. INTRODUCTION
1 .1 Background
The regulatory investigation of residential exposure to formaldehyde,
undertaken by EPA under TSCA Section 4(f), involves a reassessment of
current indoor formaldehyde exposure to residents of manufactured
(mobile), detached, and attached single-family homes and the estimation
of reductions in exposure that may result from implementing formaldehyde
emission control options. In order to carry out this investigation, the
Exposure Evaluation Division (EED) needs considerable data, primarily
those reflecting (1) indoor formaldehyde concentrations resulting from
only pressed-wood product sources (many other indoor sources are known),
and (2) concentrations resulting from different combinations of sources
too numerous to simulate in a laboratory chamber. The limited data that
have been collected do not provide this information. Furthermore,
different data sets collected and analyzed under varying methods and
conditions often do not correlate well with one another. Therefore,
though mathematical modeling poses an analytical challenge and has
definite limitations, it may be very useful and relatively inexpensive to
use for this evaluation.
To this end, a formaldehyde exposure model has been developed to
assess the relative impact of various types and loadings of pressed-wood
products and various air exchange rates on formaldehyde levels in homes.
The functions of the computerized model are to (1) estimate the initial
steady-state formaldehyde concentration in a new home, based on the
emission rates of specified pressed-wood products used in home
manufacture and the unique behavior of the chemical in the indoor
environment; (2) estimate the resulting indoor air concentration after a
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specified period of occupancy and assumed environmental conditions, based
on a decay curve function statistically derived from historical data on
formaldehyde levels in manufactured homes of various ages; and (3)
estimate the long-term average daily inhalation exposure to the
occupants.
It is important to note that this exposure model has not been
validated and is intended to only provide rough estimates of potential
formaldehyde exposures resulting from use of currently marketed pressed
wood products and to indicate relative improvements in indoor air quality
and formaldehyde exposure that may result from the employment of one or
several formaldehyde emission control options (i.e., substitute products
and increased ventilation).
The model is conservative in nature and may consequently overpredict
exposure. Its conservative nature arises from the use of simplifying
assumptions; formaldehyde s.inks are not factored into the model, and
emission barriers (carpeting over particleboard underlayment, coatings
and laminates on cabinets and doors) are not incorporated into the
emissions data used.
Other projects related to assessing formaldehyde exposure in
residental settings are ongoing and are discussed in another report
recently submitted to EED entitled "Formaldehyde Exposure in Residential
Settings: Sources, Levels, and Effectiveness of Control Options" (Versar
1986). That report also complements the information contained herein in
that it presents summaries of available monitoring data on indoor air
formaldehyde levels and test data on formaldehyde emissions from
"controlled" or treated pressed-wood products, as well as detailed
descriptions of the various formaldehyde emission control options
available today.
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1.2 Report Organization
This report is organized to present an overview and rationale for the
formaldehyde exposure model, a description of the model components, and a
demonstration of the model with several model runs. The sections of this
report are as follows:
Section 2. describes the three components of the formaldehyde
exposure model ending with a statement of the model's capabilities
and limitations.
Section 3. demonstrates the model by describing the necessary input
parameters and the residential scenarios developed to run the model.
The results of the model runs are presented below in Section 1.3.
Section 4. presents analyses and conclusions drawn from the model run
results.
1.3 Summary of Model Run Results
Table 1 presents maximum and average indoor formaldehyde
concentrations and average daily exposures over a ten year period for
different residential scenarios using the formaldehyde model.
The scenarios, all unique combinations of residential
characteristics, were designed to reflect either typical, reasonable
worst-case or best-case conditions for potential inhalation exposure to
indoor formaldehyde levels. The characteristics that vary in the
scenarios include: home type (manufactured, detached or attached);
pressed-wood product loading (square feet per home volume); emission
profile of the constituent pressed-wood products (type of resin used and
relative formaldehyde emission rate); and a range of reported indoor air
exchange rates (home ventilation rates). In every case, combinations of
these characteristics are based on reported construction practices.
More information on the characteristics of the residential scenarios
is presented later in Section 3. Analyses and conclusions drawn from the
results presented in Table 1 are described in Section 4.
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520 1H
Table 1. Sumnary Table for Formaldehyde Model Runs
Run
no.
Home
type
Emission
profile
Loading
class3 ACH
Background
level
(ppm)
Imt lal
concentration
(ppm)
Mean
concentration
(ppm)
Exposure
(mg/day)
Manufactured
Manufactured
Maufactured
Maufactured
Avg
Avg
Avg
Avg
0.25
0.50
0.75
1 .00
0.027
0.016
0.012
0.010
0.446
0.357
0.298
0.255
0.178
0.141
0.117
0. 100
3.530
2.803
2.322
1 .979
Detached
Detached
Detached
Detached
Avg
Avg
Avg
Avg
0.25
0.50
0.75
1 .00
0.16
0.014
0.009
0.007
0.297
0.206
0. 158
0. 128
0.116
0.080
0.061
0.049
2.311
1 .584
1 .203
0.970
9
10
11
12
Attached
Attached
Attached
Attached
Avg
Avg
Avg
Avg
0.25
0.50
0.75
1 .00
0.020
0.012
0 .009
0.008
0.296
0.206
0.157
0.128
0.116
0.080
0.061
0.049
2.308
I .581
1 .201
0.969
13
14
15
16
Manufactured
Maufactured
Manufactured
Manufactured
Low
Avg
Subst
High
0.50
0.50
0.50
0.50
0.016
0.016
0.016
0.016
0.149
0.357
0.025
0.382
0.057
0. 141
0.012
0.151
1.136
2.803
0.248
3.002
17
18
19
20
Detached
Detached
Detached
Detached
Low
Avg
Subst
High
0.50
0.50
0.50
0.50
0.014
0.014
0.014
0.014
0.083
0.206
0 .025
0.319
0.032
0.080
0.012
0. 126
0.631
1 .584
0.247
2.495
21
22
23
24
Attached
Attached
Attacned
Attached
Low
Avg
Subst
H igh
0.50
0.50
0.50
0.50
0.012
0.012
0.012
0.012
084
206
027
322
0.032
0.080
0.013
0. 127
0.638
1 .581
0.258
2 513
25
26
27
28
Manufactured
Manufactured
Manufactured
Manufactured
Avg
Avg
Avg
Avg
0.50
0.50
0.50
0.50
0.016
0.016
0.016
0.016
357
319
203
065
0.141
0. 125
0.078
0.025
2.803
2.488
1 .557
0.503
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5201H
Table 1 . (continued)
Run
no.
Home
type
Emission
profile
Loading
class3
ACH
Background
level
(ppm)
Initial
concentration
(ppm)
Mean
concentration
(ppm)
Exposur
(nig/da*
29
Detached
Avg
A
0.50
0 . 014
0.206
0.080
1.584
30
Detached
Avg
B
0.50
0.014
0.095
0.036
0.720
31
Detached
Avg
C
0.50
0.014
0. 186
0.072
1 .427
32
Detached
Avg
D
0.50
0.014
0.061'
0.024
0.471
33
Detached
Avg
E
0.50
0.014
0.199
0.077
1.531
34
Detached
Avg
F
0.50
0.014
0.081
0.031
0.620
35
Detached
Avg
G
0.50
0.014
0.179
0.069
1 .368
36
Detached
Avg
H
0.50
0.014
0.045
0.018
0.365
37
Attached
Avg
A
0.50
0.012
0.206
0.080
1 .581
38
Attached
Avg
B
0.50
0.012
0.103
0.039
0.779
39
Attached
Avg
C
0.50
0.012
0.189
0.073
1 .447
40
Attached
Avg
D
0.50
0.012
0.075
0.029
0.571
41
Attached
Avg
E
0.50
0.012
0. 197
0.076
1.516
42
Attached
Avg
F
0.50
0.012
0.087
0.033
0.660
43
Attached
Avg
G
0.50
0.012
0. 173
0.067
1.326
44
Attached
Avg
H
0.50
0.012
0.056
0.022
0.442
a A
B
With all present: underlayment
Without under]ayment
, cabinetry, :
shelving, paneling,
, and interior
doors.
C Without paneling
D Without underpayment or paneling
E Without doors
F Without underlayment or doors
G Without paneling or doors
H Without under!ayment, paneling and doors
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2. MODEL DESCRIPTION
This formaldehyde exposure model is composed of three interactive
components. The first component predicts the initial steady-state (or
equilibrium) level of formaldehyde due to releases from the pressed-wood
products found in a new home. This component is a simple one-compartment
model that uses the fundamental mass balance equation and either an
iterative computation loop or the Matthews or HBF Models (see
Section 2.1) to calculate the steady-state concentration resulting from
releases from multiple pressed-wood product sources. The primary input
to this component is emission rate algorithms (i.e., emission rate as a
function of background formaldehyde levels) for specific pressed-wood
products.
The second component of the model is a decay curve function that
reduces the initial concentration of formaldehyde in the new home (from
component number one) over a specified period of time. Because neither
long-term emission rate decay information for pressed wood products nor
long-term formaldehyde concentration decay in actual homes are available,
historical data on formaldehyde levels in numerous manufactured homes of
various ages were used. With this function, exposure levels at any time,
or the average level of exposure over a period of time, can be predicted.
The third component is a simple calculation to yield the inhalation
exposure values. A concentration in mass per volume from component
number two is multiplied by an inhalation rate in volume per time period
yielding an exposure in mass per time period. This result can be
adjusted to reflect an averaged annual or daily exposure or an exposure
per unit body weight.
Since components one and two are the bulk of this model, and both
required a significant amount of development, details on their derivation
and operation are discussed more extensively in the following
subsections. A summary of the exposure model's capabilities and
limitations is presented at the end of this section.
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2 .1 Initial Formaldehyde Concentration (Component 1)
The ability of mathematical models to simulate formaldehyde
concentrations in a one-compartment environment depends on two types of
factors, those that affect source emission rates, and those that
influence the dispersion of formaldehyde in an indoor environment.
Although these groups appear to be two distinct entities, they are
really mutually dependent because of formaldehyde's unique behavior.
Formaldehyde emission rates from pressed-wood products are dependent on
the background formaldehyde concentration in the indoor volume, while at
the same time, the formaldehyde concentration is dependent on the
formaldehyde emission rates.
Quantifiable factors that affect formaldehyde emission rates include:
Product and use.
Temperature.
Relative humidity.
Product loading.
Venti1ation rates.
The factors that influence the dispersion of formaldehyde in an indoor
compartment include:
• Ventilation rates.
• Extent of non-ideal indoor air mixing.
• Indoor volume.
These factors, together with actual formaldehyde emission rate data for
products tested under controlled experimental conditions, can be used in
a mathematical model that attempts to simulate the indoor dispersion
cond i tions.
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A discussion of the fundamental "mass balance" equation is
appropriate at this point to explain the modeling of indoor air
movements. The principle, simply stated, is that mass flow into and out
of a fixed volume must be equal; further, the rate of change of the
pollutant level is determined by the rate of generation and the rate of
removal. The concept could be mathematically expressed to represent
formaldehyde behavior in an indoor environment as:
n n
V dc = m ¦ Q'C0Ut + 2 Ei - m-Q-C - I Sj
dt i i
where
C0ut = Formaldehyde concentration in the outdoor environment
C = Formaldehyde concentration in the indoor environment
t = Time
V = Indoor volume
Q = Ventilation air flow through the indoor volume
m = Factor to account for non-ideal mixing
Ei = Emission rate of a formaldehyde release site
Sj = Sorption rate for a formaldehyde absorbent site
Component 1 of the model is designed to accept the following input
parameters, as specified by the user:
• Home/compartment dimensions
• Mixing factor (assumed to be ideal in this report)
• Air exchange rate
• Pressed wood product emission rate algorithms or HBF Model
parameters (see Table 2)
• Surface area they cover in the compartment
• Starting indoor formaldehyde concentration (from other sources).
The output from this model component includes:
• Input summary.
• Steady-state indoor air concentration.
• Steady-state cumulative source emission rate.
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520^..
Table 2. Linear Formaldehyde Emission Models Based on Environmental Chamber Data Taken at 23° C, 50% RHa
No. of Measured Matthew's emission mode)se HBF mode) parametersf
Product Product data concentration ER = m (ppm) + b
type code'' points'" N/L range'' range {ppm) slope intcpt corr. C^q K corr.
(m/hr) (mg/m^hr) coeff. (ppm) (m/hr) coeff.
Particle board
PCB tt
1
3
0.127
to
0,
.633
0
.077
to
0,
. 162
-0,
.32
0.
.09
-0.
.96
0
.20
0.
.37
0,
.99
underlayment
PCB tt
2
8
0.237
to
5,
.70
0
.056
to
0
.433
-0
.59
0
.43
-0
.99
0
.56
0
.64
0,
.99
PCB tt
3
8
0.101
to
0.
.949
0.
.084
to
0.
.202
-0
.48
0.
.13
-0
.84
0.
. 19
0,
.70
0.
.96
PBU 1
tt 4
4
0.159
to
9,
.18
0
.084
to
0,
.215
-1
.72
0,
.46
-0
.88
0,
.19
2,
.51
0,
.96
PBU 3
H 3
4
0.444
to
6.
.67
0,
.058
to
0.
.442
-0,
.70
0.
.51
-0.
.98
0,
.63
0.
.67
0,
.99
"Avg.
PBU"
-0
.60
0,
.38
"Max.
HUD-certi f iable"
-0,
.60
0.
.65
Industrial
PBI 3
tt 2
A
0.316
to
3.
.31
0,
.096
to
0.
,457
-0,
.47
0.
.42
-0.
.94
0,
.60
0,
.62
0,
,99
part i cleboard
"Avg.
PBI"
-0
.47
0
.37
"Max.
HUD-cert i f iabl e"
-0,
.47
0.
.60
Med i urn
MDF 1
tt 5
A
0.944
to
6.
.67
0.
.143
to
0.
.444
-1,
.65
1.
.47
-0.
.85
0,
.73
1.
.65
0,
,99
densi ty
M0F 3
tt 5
A
1 .33 I
to
12.
.5
0
.160
to
0,
.936
-1 .
.00
2.
.49
-0,
.90
1
.56
1 ,
.41
0
.99
f i berboard
"Avg.
MDF"
-0,
.94
1 .
.62
Hardwood
PNPR 2
! * 3
4
0.313
to
6.
.57
0.
.085
to
0.
,719
-0,
.46
0.
.67
-0.
.93
0,
.84
0.
.73
0.
,99
piywood
PNPR :
) tt 3
4
0.445
to
3.
.34
0
.029
to
0.
.127
-0
.37
0.
.13
-0,
.97
0,
.31
0,
.34
0.
.99
paneli ng
PAN tt
2
7
0. 100
to
1.
.90
0.
.022
to
0.
,055
-0,
.78
0.
.06
-0,
.85
0,
.06
0.
.93
0,
.97
(print)
PAN tt
3
4
0.127
to
0.
.475
0.
.015
to
0.
.017
-0
.012
0.
.005
-0,
.02
0,
.02
5.
.82
0,
. 13
"Avg.
PNPR"
-0.
.40
0.
.33
"Max.
HUD-cert i f i
i able"
-0
.40
0.
.23
Hardwood
PNP 2
tt 4
4
0.313
to
6.
.57
0.
.037
to
0.
.426
-0
.27
0.
.27
-0
.78
0,
.77
0,
.41
0,
.99
piywood
PNP 3
tt 1 ,29
4
0.202
to
1 .
.11
0.
.063
to
0.
,225
-0,
. 10
0.
.09
-0.
.83
0,
.69
0.
. 11
0,
,99
paneli ng
PNP 3
tt 1 ,2h
3
0.171
to
1 .
. 11
0
.129
to
0.
.402
-0
.27
0.
.22
-0
.99
0,
.67
0.
.27
0
.99
(paper)
"Avg.
PNP"
-0.
.22
0.
. 14
"Max.
HUD-certi f i
iable"
-0
.22
0.
. 18
Hardwood
PND 1
tt 1 ,29
4
0.152
to
0.
.355
0
.105
to
0.
.194
-0,
.19
0,
.08
-0,
.60
0,
.24
0,
.36
0,
.84
piywood
PND 1
tt 1 ,2h
4
0.125
to
1 ,
.06
0.
.055
to
0.
.248
-0,
. 1 1
0.
.08
-0.
.90
0,
.51
0.
.13
0,
.99
pane 1i ng
PND 3
tt 5
3
0.318
to
1 .
.11
0
.062
to
0.
.137
-0,
.34
0.
. 11
-0,
.95
0,
.24
0,
.39
0,
.99
(domest i c )
PAN tt
1
A
0.136
to
1.
.90
0.
.072
to
0.
.162
-0
.47
0.
.13
-0.
.92
0.
. 18
1.
.31
0.
.99
"Avg.
PND"
-0
.27
0,
. 15
"Max HUD-certifiable" -0.27 0.20
-------
52C.
Table 2. (conti
nued)
No. of
Measured
Matthew's emission
modelse HBF model parameters^
Product
type
Product
code'1
data
points'- N/L range1'
concentrat i on
range (ppm)
ER =
si ope
(m/hr)
m (ppm) +
1 111 c p t
(mg/m^hr)
b
corr. C^q K corr.
coeff. (ppm) (m/hr) coelf.
So f twood
piywood
(PF resin)
INPLYPF #
1 5 0.23 to 1.05
0.017 to 0.029
-0.61
0.03
0.03 0.66 0.98
Hardboard
(e.g., "Masoni te" )
HBD 1
7
0.02 to 0.O95
-1 .39
0. 17
-0.99
aIhe data listed in this table are based on the results of emission rate tests performed at Oak Ridge National Laboratory
(ORNL) for the Consumer Product Safety Commission (CPSC) under Interagency Agreement CPSC-IAG-82-1297. The data listed in the
table for individual boards were obtained from or are based on the results reported in Progress Reports No. I, II, XIV, XV, and
XVI submitted to CPSC by ORNL.
Ihe emission rate models (or "average" product types are taken from Matthews et al. (1983a).
The slope values were reported by Matthews to represent the typical average slope for three or more boards for each product
type that were tested in ORNL's environmental chamber. It is not known whether these "average" slopes were calculated using a
subset of the individual board data presented in lable 2 or additional board data not reported in Table 2. The intercept
values were calculated by Matthew's using the "average" slope values and the "average" emission rate measured (using the FSEM
monitor) for boards collected during CPSC's Pressed Hood Product Survey in 1983.
The "Max. HUD-certifiable" product models were calcuated using the slope values for Matthews' "average" product types and the
maximum chamber concent rations allowed by the HUD standards (i.e., 0.3 ppm for particleboard and 0.2 ppm lor paneling).
^Product codes are reported as listed in the ORNL Progress Reports (except for interior plywood and hardboard).
cEach data point typically represents the average of three measurements at a particular N/L value.
^N/L is the ratio of the experimental air exchange rate (N), in changes per hour, to the product loading in the chamber (L),
in m^ of product surface area per nrf of chamber volume.
eER is the emission rate of the product in units of mg of formaldehyde per m^ of product surface area per hour; intercept
lias the same units. Units of slope are ni/hr.
'hBF model parameters, C[:q and K, are in units of ppm and m/hr, respectively.
90nly decorative side exposed.
^Both sides exposed.
-------
2.1.1 Iterative Computation Loop Solution
This model employs the mess balance equation in a fashion that
accounts for the unique behavior of pressed-wood products emitting
formaldehyde and uses the product-specific emission rate equations made
available by CPSC (generated by Oak Ridge National Laboratory from
environmental chamber data, presented in Table 2).
Due to the interdependence of formaldehyde emission rates and indoor
air concentration, it is necessary to stop the mass balance calculation
at a given time interval, adjust the emission rates to reflect the new
indoor air concentration, and then start calculating again based on the
adjusted emission rates until the end of the next time interval. The
model proceeds with this iterative computation until it detects that an
equilibrium air concentration of formaldehyde has been reached (i.e., a
substantial succession of insignificantly varying concentrations).
It is important to note that the iterative technique is not usually
used in other indoor air calculations. Typically, indoor contamination
levels result from a continuous emission that mixes and ventilates
throughout a compartment over time. With pressed-wood product
formaldehyde emission, emission is not continuous. It varies over time
depending on the existing indoor concentrations and other environmenta1
conditions. This real life phenomenon is reflected in the model by
breaking up the overall concentration calculation into many smaller
calculations, or iterations.
The iterative interval (or the designated time at which the
calculation stops, adjusts, and starts again) may be altered while
running a particular scenario with little effect on the model results.
An interval change will simply increase or decrease the number of
calculations before the equilibrium concentration value is reached; the
- 11 -
-------
time (number of days) to reach equilibrium may vary slightly, but the end
value will always be the same. It has been suggested, however, that an
iterative interval of six hours (1/4 day), or less, relates most closely
to actual emission rate fluctuations and is most compatible with the
empirical emission rate data used in the model.
A copy of the computer program is included in Appendix A.
2.1.2 Matthews et al. Simple Steady-State Model for Indoor
Formaldehyde Concentrations
The Matthews et al. model is designed to estimate steady-state
formaldehyde concentrations resulting from emission sources in a single
compartment. The following discussion is in large part excerpted from
Matthews et al. (1983a). The underlying theory of the model and its
derivation are described in Matthews et al. (1983a, 1983b).
At steady-state, the formaldehyde concentration in a single
compartment may be expressed as:
[CH20]ss = [CH20]o + CH20ER/(C x ACH x VOL) (1)
where
[CH2O= steady-state concentration inside the compartment (mg/m^),
[CH20]o = steady-state concentration outside the compartment (mg/m^),
CH20ER = the emission rate of formaldehyde sources inside the
compartment (mg/h),
C = the fraction of air coming into the compartment that mixes within
the volume (i.e., the mixing factor),
ACH = the flow rate of air through the compartment in compartment volume
per time (hr_1), and
VOL = the volume of the compartment (m^).
- 12 -
-------
The multiplicative product of C and ACH is termed by Matthews et al. as
PEX, the effective pollutant exchange rate (in units of hr~^).
Equation 1 therefore becomes
[CH20]ss = [CH20]o + CH20ER/(PEX x VOL) (2)
Application of the model as expressed in Equation 2 is simplified by
assuming that all parameters in the equation remain constant (at
steady-state) and that there are no permanent losses of formaldehyde due
to irreversible sorption to sinks.
Equation 2 must be rewritten to accomodate the different
characteristics of various sources of formaldehyde emissions; emission
rate expressions are substituted for CH^OER in the equation. The three
types of formaldehyde emissions, each of which is treated somewhat
differently by the model, are:
(1) Solid emission sources in direct contact with indoor air (such
as hardwood plywood paneling).
(2) Solid emission sources that have a barrier, reducing emission
rate, between the source and the indoor compartment (for
example, particleboard underlayment with a carpet barrier).
(3) Combustion sources (cigarettes, gas appliances, etc.)
The first two types of sources listed above are area-dependent in that
the magnitude of the emission is a direct function of the surface area of
the source in the compartment. The equivalent of Equation 2 for
area-dependent sources is
[CH20]ss = [CH20]o + CH20ER" Area/(PEX x VOL) (3)
with CH20ER' in units of mg/m^hr and area in m2.
The third, combustion sources, may be modeled with Equation 2
(assuming that the emission rate is constant over time). The emissions
expressions for the area-dependent sources, both with and without
barriers, are discussed below.
- 13 -
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Fick's Law describes the bulk-vapor interphase at the surface of a
solid emission source. If one assumes that the mass transport
coefficient and the formaldehyde concentration in the bulk phase are
independent of the formaldehyde concentration in the vapor phase, the
emission rate of a solid source is:
CH20ER' ~-m [CH20]v + b (4)
where
m = the mass transfer coefficient (m/hr)
[CH20]v = the CH2O concentration in the vapor phase (mg/m^)
b = a constant; the emission rate at zero CH2O concentration in
the air (mg/m2hr)
Therefore, Equation 5 (Equations 3 and 4 combined) is used to calculate
the concentration inside a single compartment with a solid emission
source in direct contact with the air:
[CH20]ss = (Area/(PEX x VOL) x b + [CH20]o)/(l + m (Area/(PEX x VOL)) (5)
The third type of formaldehyde source is a solid, area-dependent
source with an emission barrier (such as carpet or a vinyl laminate).
Again, Fick's Law describes formaldehyde transport across such permeation
barriers:
CH20ER' = K([CH20]B6 - [CH20]SS) (6)
where
K = mass transport coefficient for the permeation barrier (m/hr)
[CH20]bb = formaldehyde concentration below the barrier (mg/m^)
CCH201ss = formaldehyde concentration above the permeation
barrier (mg/m^)
If it is assumed that there are no concentration gradients above or below
the barrier, Equation 7 applies:
CH20ER' = -m [CH20]bb + b (7)
- 14 -
-------
This simplifying assumption results in an overestimation of CH^OER1
because the presence of the barrier will in fact cause concentration
gradients near the surface of the source, which would reduce CH^OER'.
The emission model for a solid source and a permeation barrier is, by
combining Equations 6 and 7,
CH20ER' = (b-m x [CH20]ss)/1 + m/k) (8)
The concentration inside a single compartment with this type of
source is calculated via Equation 9:
[CH20]ss = (Area/(PEX x VOL)) x b + [1 + (m/K) x [CH?03n] (9)
1 + (m/K) + m (Area/(PEX x VOL)) " ~
Equation 9 holds for barriers of intermediate efficiency in emission
reduction; for very inefficient barriers (i.e., K>>1), Equation 5
applies. For extremely efficient barriers (KIO), the source may be
disregarded by assuming that [CH203<-S is approximately equal to
[CH-01 .
2 o
Equations 2, 5, and 9 describe the calculation of [C^O]^ for
indoor compartments with combustion, direct, and source-barrier
combination sources alone. For a single compartment with multiple
formaldehyde sources, Equation 10 may be used to derive the steady-state
concentration [CH^O]^:
n
[CH20]ss = [CH20]o + I (CH20ER/(PEX x VOL)
i = 1
v
+ I (CH20ER' x Area)/(PEX x VOL) (10)
i = 1
with proper emitter equations (such as Equations 4 and 7) substituted for
CH20ER¦*.
- IB -
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2,1.3 HBF Simple Steady-State Model for Indoor Formaldehyde
Concentrations
The HBF model (name coined by Myers (1984)) is a model developed by
Hoetjer (1978) for which mathematically identical versions have been
developed by Berge et al. (1980) and Fug i i et al. ( 1973). The underlying
theory and derivation of the model are summarized in Myers (1984).
The HBF model equation for steady-state concentration for a single
source is
[CH20]ss = [CH20]Eq (11)
1 PEX x VOL
1 + k X AREA
where [CH^O]^ is the equilibrium concentration in the air when
PEX=0; and k is the mass transfer coefficient analogous to Matthew's
model parameter "m".
Inversion of equation 11 leads to
1 = 1 + 1 X PEX x VOL (12)
[CH20]SS [CH20]EQ [CH20]Eq x k AREA
1 PEX x VOL
so that a plot of [CH20]ss versus AREA yields a straight line
wi th
intercept 1 and slope 1 .
[CH20]Eq [CH20]Eq X k
*For multiple solid emission sources, the third
term of equation 10 is solved as follows:
v AREA x b \
I VOL ) + PEX x [CH20]0
PEX +- v AREA x m
E VOL
i = 1
- 16 -
-------
For multiple sources, the model equation is
/ v AREA x k\ (13)
( I [CH20]Eq x VOL ] + PEX x [CH20]0
CCH20]SS = \i=l J
v AREA x k
PEX + I VOL
i = l
2.2 Decay Curve Function (Component 2)
Once the steady-state indoor air concentration of formaldehyde in the
home is estimated, that concentration is decayed over time to reflect the
decay of formaldehyde emissions from the wood products. The decay curve
function used by the model is derived from available formaldehyde
monitoring data in mobile homes, where indoor air concentration is
reported as a function of the age of the mobile home. It is acknowledged
that these concentrations will not be attributable solely to emissions
from pressed-wood products. Other sources of formaldehyde in residential
settings (such as outdoor air, cigarettes, and emissions from gas
appliances) may remain constant with time, rather than decaying. The
presence of those sources can be accounted for by introducing a constant
into the decay curve equation.
Two studies that provided compatible mobile home air monitoring data
for formaldehyde were selected to create an aggregated set of data: a
study done by Clayton Environmental Consultants for the Department of
Housing and Urban Development (Singh et al. 1982), and a survey performed
by the State of Wisconsin Division of Health (Anderson et al. 1983). The
combined data set of 1,179 observations has a concentration range of 0.02
to 2.9 ppm. The mean for this distribution is 0.43 ppm; the median is
0.31 ppm; the 75th percentile is 0.55 ppm; the 90th percentile is 0.89
ppm; and the coefficient of variation is 90.6 percent.
The ages of the homes range from 0 to 3400 days. Homes less than
three years old have an average formaldehyde level of 0.51 ppm, and homes
over three years old average 0.15 ppm.
- 17 -
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The data from each study were particularly compatible because of the
following common characteristics:
• Formaldehyde was measured by the chromotropic acid method or by
the pararosani1ine method.
• Each data point was the average of several measurements taken on a
particular day, and the age of the mobile home at the time of
measurement was given.
• Both studies sampled predominantly "non-complaint" homes.
• QA/QC in both studies was reportedly good.
Figure 1 presents a plot of the aggregate data set (mobile home age
versus formaldehyde concentration), which confirms the decay of initial
average level of formaldehyde with the increase in mobile home age. In
this graph, the formaldehyde levels (y values) have been standardized for
consistent temperature and relative humidity. Based on this graph, it is
clear that a linear function is not the best way to describe the data.
Consequently, the exponential and power mathematical models were
evaluated to determine the function of a curve that best described (or
fit) the data.
The evaluation of these models involved developing several different
statistical approaches for manipulating the data under the exponential
and power laws. The description and results of these statistical
evaluations are detailed in the earlier cited report submitted by Versar
(1986). The final decision was to select the exponential model as the
best fit for the data presented. The resulting decay function employed
by the exposure model is as follows:
y . .504e-'00065<
where y is the concentration in ppm and x is the age of the home in days.
- 18 -
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-------
2
The correlation coefficient for the equation is 0.59 and the R
value is 0.35, implying that home age determines approximately 35 percent
of the home formaldehyde level, while all other factors combined
determine the other 65 percent of the variability. The formaldehyde
half-life predicted by this equation is about three years.
The use of this formaldehyde decay model in this report includes a
constant to represent the non-decaying background formaldehyde level:
v , , r -.00065x
Y = constant + Ce
where C is the predicted initial steady-state formaldehyde concentration
in the home. The constant was determined by the type of home and the. air
exchange rate; Section 3 discusses the values assigned to the constant
under different scenarios.
The input requirement for the decay curve (the second model
component) is the duration of exposure and the initial steady-state
formaldehyde concentration in the home. The third component (exposure
calculation) requires inhalation rate; other exposure-related parameters
are optional.
The final model output includes:
Summary of the input parameters.
Maximum concentration.
Minimum concentration.
Average daily concentration.
Average daily exposure.
2.3 Capabilities and Limitations of the Model
Computerization of the equations described above provides the model
user with the capability to rapidly estimate formaldehyde exposure for
different scenarios. Several features of the computerized model include
the abi1i ty to:
- 20 -
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• Estimate the inhalation exposure to formaldehyde from pressed-wood
product sources.
• Analyze the combined effect of several pressed-wood products in
one compartment.
• Predict both short- and long-term exposures.
Several key assumptions and limitations are important to note,
however, when using the model and evaluating its results:
1. Although both the Matthews and HBF Steady-State Models (i.e.,
component #1) have been reported to provide excellent
predictions of formaldehyde concentrations in laboratory
experiments under near ideal air mixing conditions, neither has
been validated for predicting concentrations in actual homes
with occupants.
2. This is a one-compartment model. Exposure is estimated for just
the one compartment and is assumed to reflect the exposure
level, as an average, in all of the individual rooms of the home
(or compartment). This may be a valid assumption for mobile
homes where pressed-wood product distribution throughout the
home is relatively uniform; the validity of this assumption for
low and dispersed loadings of products is questionable. The
Clayton study (Singh et al. 1982) stated that occupied single-
and double-wide mobile homes are consistent in overall
concentrations, as are the unoccupied homes; the size of the
home and number of rooms do not appear to be affecting factors.
3. Initial steady-state concentrations can be estimated by the
model only for those pressed-wood products for which appropriate
emission rate data are provided (i.e., emission rate algorithms
or HBF Model parameters). The emission rate data used for this
model are limited to data collected at 23°C and 50 percent
relative humidity using small dynamic test chambers. The tested
products were collected during 1983 and thus may not be
representative of current products.
4. Potential degradation of formaldehyde is not accounted for by
the model. Loss due to formaldehyde "sinks" in the indoor
environment is not accounted for in the iterative computation
and Matthews models; during the calculation of the initial
indoor air concentration, the models assign zero to any negative
emission rate (formaldehyde absorption by pressed-wood products)
resulting from high vapor concentrations. The HBF model does
account for pressed wood products that may act as "sinks."
- 21 -
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5. The effect of vapor barriers, such as paint or carpet over the
pressed-wood product, are also not accounted for by the model.
6. When calculating the initial indoor air concentrations, the
model assumes a constant ventilation rate, temperature (23°C),
and relative humidity (50 percent) and ideal mixing factor.
7. Because information on the long-term decay of formaldehyde
emissions from wood products is not available, the decay curve
function of the model is derived from monitoring data collected
in numerous mobile homes of various ages. It is important to
note several limitations to this approach: (a) the monitoring
data reflect concentrations due in part to sources other than
pressed-wood products; (b) the pressed-wood products marketed
today are manufactured using UF resin systems significantly
different from those used to manufacture the wood products
contained in the surveyed mobile homes; (c) because comparable
monitoring data are not available for conventional homes, the
mobile home data have been used for modeling conventional home
scenarios; and (d) decay of concentrations related to emissions
from phenol-formaldehyde (PF) products are assumed to parallel
decay of formaldehyde from the UF products present in the homes
in the Wisconsin and Clayton studies. Formaldehyde from PF
resins may behave differently (either with a faster or slower
decay).
- 22 -
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3. MODEL INPUT REQUIREMENTS
The purpose of this section is to demonstrate the formaldehyde
exposure model through the description of the input parameters and the
fifty residential scenarios used to drive the model.
3.1 Home Dimensions
Two basic mobile home types exist, a single-wide home and a
double-wide home. Single-wide homes typically are 12 to 14 feet in width
and 60 to 75 feet in length. Double-wide homes generally measure 24 to
28 feet in width and 50 to 70 feet in length (ICF 1985). Based on the
known market share of each basic type in 1981, ICF (1986a) calculated a
weighted-average "model" mobile home with a floor area of 983 square feet
and an assumed ceiling height of 8 feet. Based on these dimensions a
nominal interior volume of 7,864 cubic feet can be calculated. However,
this estimate does not account for the fact that interior walls,
appliances, etc. occupy some of the volume. Groah et al. (1985)
estimated the approximate inside volume of nine mobile homes to be about
0.88 times the nominal interior volume. Applying this factor of 0.88 to
the ICF model volume of 7,864 cubic feet, yields an estimated interior
volume of 6,920 cubic feet.
NAHB (1986) found in their survey of 1984 single-family home
construction practices that the average floor areas of detached and
attached houses were 1,684 square feet and 1,224 square feet,
respectively. Assuming a ceiling height of eight feet, the average
inside volumes can be estimated to be 13,472 cubic feet and 9,792 cubic
feet, respectively.
3.2 Pressed Wood Product Loadings
Loading refers to the surface area (or square footage) of board
relative to the volume of the home. The UF pressed wood product loading
- 23 -
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rates used in this report are based on information from three sources:
ICF (1986a), ICF (1986b), and NAHB (1986). Table 3 summarizes the
estimated average loading rates of these products when they are present
in the three home types.
ICF (1986a) estimated the loading rates of pressed wood products in
mobile homes. NAHB (1986) supplied the loading rates for particleboard
underlayment and shelving and for paneling use and interior doors in both
single family detached and attached houses. Based on NAHB (1986) data,
ICF (1986b) estimated the quantities of particleboard and hardwood
plywood used to construct cabinets in single family houses. A copy of
NAHB (1986) is attached to this report as Appendix B. The relevant
sections of ICF (1986a) and ICF (1986b) dealing with estimation of
cabinetry uses of pressed wood products are attached as Appendices C and
D, respectively.
3.3 Emission Rate Input
Chamber testing to generate the emission rate equations needed to run
the model has been performed and the results published for relatively few
pressed wood products. Table 2 presents the emission rate equations
measured and reported by ORNL (Matthews et al. 1981-1985). Emission rate
equations have been reported for five particleboard underlayment and
eleven hardwood plywood paneling samples. However, no emission rate
equations are readily available for mobile home decking and only one
*
sample each of industrial partic1eboard, softwood plywood (PF resin),
and hardboard* (PF resin) have been characterized. Matthew's et
Although emission rate equations are available for only one sample
of softwood plywood and hardboard, the formaldehyde concentrations
predicted using these equations at conditions of N/L = 1.2 are
within the range of concentrations measured in chamber tests of
numerous PF resin products at this N/L ratio (range = 0.01 to 0.08
ppm) (Versar 1986).
- 24 -
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5205H
Table 3. UF Pressed Wood Product Loadings in Homes Containing These Products3
Component
Loading (when present). ^
Manufactured Detached Attached
Percent of homes containing product
Manufactured Detached Attached
Particleboard
Underlaymentc
900
(0.130)
1,494
(0.111)
1 ,034
(0.106)
64
7.2
5.6
Cabi nets
129
(0.019)
249
(0.018)
238
(0.024).
-100
-100
-100
Shelvi ng
31
(0.002)
25
(0.002)
47
46
Paneli ng
2,216
(0.320)
347
(0.026)
218
(0.022)
70
12.2
6.3
Cabi nets
Interior doorse
176
(0.025)
155
(0.022)
132
(0.010)
333
(0.025)
126
(0.013)
300
(0.031)
-100
-100
35
-100
33
a Primary sources of data: NAHB (1986), ICF (1986a), ICF (1986b).
^ Estimated average interior volumes are: manufactured homes (6,920 ft^), single family detached
(13,472 ft^), single family attached (9,792 ft^) .
c Loadings do not account for underlayment used in kitchen and bathroom areas (i.e., -190 ft^ in single
family homes and 83 ft^ in manufactured homes).
d No estimate for shelving made in ICF (1986a,b).
e Assumes manufactured home has 5 interior doors of dimensions, 28" x 30", single family detached home has
10 doors of dimensions, 30" x 80"; single family attached home has 9 doors of dimensions, 30" x 80".
-------
al. (1983a) has estimated "average" emission rate equations for various
product types using the data from the characterized samples combined with
data gathered on a larger set of products using the formaldehyde surface
emission monitor.
Because relatively few boards have been characterized, it is
worthwhile to examine how representative these boards may be of currently
marketed products. Table 4 presents estimates of the chamber values
predicted for each of the products listed in Table 2 assuming the test
was performed under the testing conditions specified in the Department of
Housing and Urban Development's (HUD) Manufactured Home Construction and
Safety Standards (24 CFR 3280) with the exception that the HUD test is
performed at 25°C and the predicted concentrations are at 23°C. As can
be seen from the table all of the tested particleboard samples meet the
HUD standard of 0.3 ppm and 8 of 11 paneling samples meet the HUD
standard.of 0.2 ppm. The only "average" product not meeting the
respective HUD standard is the "average" print paneling. For comparison
purposes, Tables 5 and 6 present the summary results of recent testing
performed by the National Particleboard Association (NPA 1985) and the
Hardwood Plywood Manufacturers Association (HPMA 1985), respectively.
The predicted HUD test concentrations for the "average" particleboard
underlayment and "average" industrial particleboard match very well with
the average test concentrations measured by NPA (1985) for these product
lines. The "average" paper paneling and "average" domestic paneling have
predicted HUD concentrations approximately equal to the median
concentration reported by HPMA (1985).
Although emission rate equations are available for only one sample
each of softwood plywood and hardboard, the low predicted concentrations
under HUD testing conditions agree very well with the results of similar
tests performed on PF resin wood products by various investigators. The
results of tests on various PF resin wood products (summarized in Versar
1986) indicate chamber test values typically below 0.05 ppm.
- 26 -
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520SH
Table 4. Predicted Chamber Concentrations at HUD Test Conditions3'*5
Predicted HUD chamber test
Product type P-oduct code concentration (ppm)
Partideboard PCS *1 0.05
underlayment PCS ?2 0.20
PCB *3 0.06
PSU 1 *4 0.13
PBU 3 <3 0.22
"Avg. PBU" 0.17
Industrial PBI 3 *2 0.21
particleboard "Avg. PBI" 0.18
Hardwood plywood PNPR 2 #3 0.55
paneling (print) PNPR 3 #3 0.12
PAN #2 0.01
PAN #3 0.01
"Avg. PNPR" 0.29
Hardwood plywood PNP 2 #4 0.27
paneling (paper) PNP 3 #1, 2C 0.13
PNP 3 #1. 2d 0.22
"Avg. PNP" 0.15
Hardwood plywood PND 1 #1. 2C 0.09
paneling (domestic) PND 1 #1, 2d 0.10
PND 3 #5 0.10
PAN #1 0.10
"Avg. PND" 0.15
Softwood plywood INPLYPF «1 0.02
Hardboard HBO 1 0.05
a With the exception that predictions are made at 23°C rather than the
HUD test condition of 25°C the other conditions are identical (i.e.,
50% rel. humidity; 0.5 air changes per hour; partlcleboard, softwood
plywood and hardboard loading of 0.13 ft^/ft3, and paneling
loading of 0.29 f12/ft3.
^ See Table 2 for product descriptions and emission rate equations.
c Only decorative side exposed in chamber testing.
d Both sides exposed during chamber testing.
- 27 -
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5205H
Table 5. Summary of 1985 NPA HUD Certification Test Results
Product
Number of
samples
Mean
Test results (ppm)
Standard
deviation
Range
Industrial
58
0.17
0.06
0.05-0.28
Under!ayment
35
0.18
0.07
0.08-0.30
Mobile home decking
25
0.14
0.06
0.06-0.25
Total
118
0.17
0.06
0.05-0.30
Source' NPA (1985)
- 28 -
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5 2 0 5 H
Table 6. Frequency Distribution of June 1984 - Late June 1985
Chamber Test Data for Hardwood Plywood
Chamber value Cumulative
(ppm) Number of Number of
cell limits observations Percent observations Percent
0.01
-
0.05
5
6.9
5
6.9
0.06
-
0.10
12
16.7
17
23.6
0.11
-
0.15
14
19.4
31
43.1
0. 16
-
0.20
8
11.1
39
54.2
0.21
-
0.25
10
13.8
49
68.1
0.26
-
0.30
7
9.7
56
77.7
0.31
-
0.35
6
8.3
62
86.1
0. 36
-
0.40
1
1 .4
63
87.5
0.41
-
0.45
4
5.6
67
93.1
0.46
-
0.50
1
1 .4
68
94.4
0.51
-
0.55
0
--
68
94.4
0.56
-
3.60
2
2.8
70
97.2
0.61
-
0.65
1
1 .4
71
98.6
0.66
-
0.70
0
—
71
98.6
0.71
-
0.75
0
—
71
98.6
0.76
-
0.80
0
—
71
98.6
0.81
-
0.85
1
1 .4
72
100.0
Total 72 99.9
Source. HPMA (198S).
- 29 -
-------
Table 7 presents selected products whose emission rate equations will
be used in this report to represent low-emitting, "average"-emitting,
high-emitting, and UF-substitute products.
3.4 Background Formaldehyde Levels
It is acknowledged that other sources can contribute to indoor
formaldehyde levels (see Section 3 of the Versar (1986) report on
Formaldehyde Exposure in Residential Settings). These other sources
include textiles, gas appliances, and undetermined amounts of
pressed-wood products used in furniture pieces. The total effect of
these sources has not been satisfactorily researched for inclusion into
the algorithmic portion of the exposure model; however, an initial
background formaldehyde concentration attributable to these other sources
can be estimated. Table 8 shows how the following initial formaldehyde
levels were estimated as a function of air changes per hour (ACH):
ACH = 0.25 ACH = 0.50 ACH = 0.75 ACH = 1.00
Detached home 0.016 0.014 0.009 0.007
Attached home 0.020 0.012 0.009 0.008
Manufactured home 0.027 0.016 0.012 0.010
3.5 Other Parameters
(1) Home occupancy period = 10 years.
(2) Inhalation rate = 24 m^ per day. Derived from averaged lung
ventilation values of different levels of activity as a function
of age and sex, presented in Reference Man (ICRP 1974).
(3) Duration of exposure = 16 hours per day. The average
non-working portion of the day.
- 30 -
-------
S205H
Table 7. Selected Product Emission Profiles3
Component Low-emitting "Avg" emitting High-emitting Non-UF substitute
Particleboard
Under!ayment
PCB
*3
Avg
PBU
MAX
HUD
CO
Q_
INPLYPF
Ml
Cabinets
PCB
#3
Avg
PBI
MAX
HUD
PBI
INPLVPF
D1
Shelving
PCB
#3
Avg
PBI
MAX
HUD
PBI
INPLYPF
#1
Hardwood plywood
Panel ing
PNPR 3 #3
Avg
PNPR
MAX
HUD
PNPR
-
Cabinets
PND 3 #5
Avg
PND
MAX
HUD
PND
INPLYPF rfl
Interior doors
PND 3 #5
Avg
PND
MAX
HUD
PND
HBO 1
aSee Table 2 for product descriptions and emission rate equations.
- 31 -
-------
5205H
Table 8. Formaldehyde Levels Contributed by Other Sources
Source
Assumed emission
rate3
Assumed usaoeb
OH
AH
MH
Estimated 24-hr average
concentration (ppm) for a
manufactured home at a low air
exchange rate c' d¦ e
Carpeting
Upholstery
Drapery
Apparel
Gas stove
Gas oven
C igarettes
Ambient air
Total
2
13 ug/m /day
2
6 ug/m /day
2
170 ug/m /day
2
300 ug/m /day
8.6 mg/hr
13 mg/hr
1.2 mg/hr
0.005 ppm
139 m
30 m
30 m
2
96 m
30 m
30 m
84 M
19 m
19 m
2
5 m 5 m 5 m
1.0 hr/day 1.0 hr/day 1.0 hr/day
0.7 hr/day 0.7 hr/day 0.7 hr/day
10 cig/day 10 cig/day 10 cig/day
0.0007
<0.0001
0.0020
0.0009
0.0054
0.0058
0.0075
0.005
0.0273
a Assumed emission rates obtained from Versar (1986).
b
AH = Attached model home
DH = Detached model home
MH = Manufactured model home
Concentrations estimated using the following equations:
[ ] = (assumed emission rate) x (assumed usage) x (0.809 ppm/mg/m3)
(air exchange rate) x (household volume) x (24 hr/day)
Household volumes
AH = 277 m3
DH = 381 m3
MH = 196 m3
Air exchange rates for each model home are 0.25, 0.50, 0.75, and 1.00 air change/hr.
Total formaldehyde levels contributed by other sources for different air exchange rates and model home
type are
Air exchange rate QH AH MH
0.25
0.50
0.75
1 .00
0.016
0.014
0.009
0 007
0.020
0.012
0.009
0.008
0.027
0.016
0.012
0.010
- 32 -
-------
4. ANALYSES AND CONCLUSIONS
The results of the forty-four model runs (which were presented in
Table 1) are shown in order of descending formaldehyde concentrations in
Table 9. Several noteworthy conclusions can be drawn from the analyses
of these scenarios.
For no scenario did the 10-year average concentration exceed
0.4 ppm. Only one of the scenarios evaluated resulted in predicted
initial formaldehyde levels greater than 0.4 ppm. This scenario'
described a manufactured home containing average UF products in
underlayment, paneling, and cabinets, at a low air exchange rate.
Approximately 16 percent of the scenarios (7 of 44) predicted initial
levels between 0.30 ppm and 0.40 ppm. These scenarios can be generally
described as follows:
• Manufactured homes with average UF products in all product
categories, or only in paneling and cabinets at moderate air
exchange rates (0.5 air changes/hr).
• Attached or detached homes with high-emitting UF products used in
all product categories at moderate air exchange rates (0.5 air
changes/hr).
All scenarios with PF substitutes produced predicted initial levels
below 0.03 ppm.
Further conclusions regarding the choice of model used to estimate
compartment 1 (initial) formaldehyde concentrations, effect of product
emission rates, loadings, and air exchange rates are described below.
4.1 Comparison of Models
All of the model runs summarized in Tables 1 and 9 were performed
using the computerized iterative technique to estimate initial
formaldehyde concentrations. As discussed in Section 2.1, three
different models exist that could be used in this capacity: 1) the
computerized iterative model, 2) the Matthews model, and 3) the HBF
model. Figure 2 compares the initial formaldehyde concentration
predicted by each of the three models at two different air exchange rates.
- 33 -
-------
5208H
Table 9. Model Runs Sorted in Descending Order of Exposure Value
Run Emission Loading Background Initial Mean
No. Home type profile class® ACH level concentration concentration Exposure
(ppm) (ppm) (ppm) (rug/day)
1
Manufactured
Avg
A
0.25
0.027
0.446
0.178
3.530
16
Manufactured
High
A
0.50
0.016
0.382
0.151
3.002
14
Manufactured
Avg
A
0.50
0.016
0.357
0.141
2.803
25
Manufactured
Avg
A
0.50
0.016
0.357
0. 141
2.803
2
Manufactured
Avg
A
0.50
0.016
0.357
0. 141
2.803
24
Attached
High
A
0.50
0.012
0.322
0.127
2.513
20
Detached
High
A
0.50
0.014
0.319
0.126
2.495
26
Manufactured
Avg
B
0.50
0.016
0.319
0.125
2.488
3
Manufactured
Avg
A
0.75
0.012
0.298
0.117
2.322
5
Detached
Avg
A
0.25
0.016
0.297
0.116
2.311
9
Attached
Avg
A
0.25
0.020
0.296
0.116
2.308
4
Manufactured
Avg
A
1.00
0.010
0.255
0.100
1 .979
18
Detached
Avg
A
0.50
0.014
0.206
0.080
1 .584
29
Detached
Avg
A
0.50
0.014
0.206
0.080
1 .584
6
Detached
Avg
A
0.50
0.014
0.206
0.080
1 .584
22
Attached
Avg
A
0.50
0.012
0.206
0.080
1 .581
37
Attached
Avg
A
0.50
0.012
0.206
0.080
1 .581
10
Attached
Avg
A
0.50
0.012
0.206
0.080
1 .581
27
Manufactured
Avg
C
0.50
0.016
0.203
0.078
1 .557
33
Detached
Avg
E
0.50
0.014
0.199
0.077
1 .531
41
Attached
Avg
E
0.50
0.012
0.197
0.076
1 .516
39
Attached
Avg
C
0.50
0.012
0.189
0.073
1 .447
31
Detached
Avg
C
0.50
0.014
0.186
0.072
1 .427
35
Detached
Avg
G
0.50
0.014
0. 179
0.069
1 .368
43
Attached
Avg
G
0.50
0.012
0.173
0.067
1 .326
7
Detached
Avg
A
0.75
0.009
0.158
0.061
1 .203
11
Attached
Avg
A
0.75
0.009
0. 157
0.061
1 .201
13
Manufactured
Low
A
0.50
0.016
0.149
0.057
1 .136
8
Detached
Avg
A
1.00
0.007
0. 128
0.049
0.970
12
Attached
Avg
A
1.00
0.008
0. 128
0.049
0.969
38
Attached
Avg
B
0.50
0.012
0. 103
0.039
0.779
30
Detached
Avg
B
0.50
0.014
0.095
0.036
0.720
42
Attached
Avg
F
0.50
0.012
0.087
0.033
0.660
21
Attached
Low
A
0.50
0.012
0.084
0.032
0.638
17
Detached
Low
A
0.50
0.014
0.083
0.032
0.631
34
Detached
Avg
F
0.50
0.014
0.081
0.031
0.620
- 34 -
-------
520SH
Table 9. (continued)
Run
No.
Home type
Emission
profile
Loading
class3
ACH
Background
level
(ppm)
Initial
concentration
(ppm)
Mean
concentration
(ppm)
Exposure
(mg/day)
40
Attached
Avg
D
0.50
0.012
0.075
0.029
0.571
28
Manufactured
Avg
D
0.50
0.016
0.065
0.025
0.503
32
Detached
Avg
D
0.50
0.014
0.061
0.024
0.471
44
Attached
Avg
H
0.50
0.012
0.056
0.022
0.442
36
Detached
Avg
H
0.50
0.014
0.045
0.018
0.365
23
Attached
Subst
A
0.50
0.012
0.027
0.013
0.258
15
Manufactured
Subst
A
0.50
0.016
0.025
0.012
0.248
19
Detached
Subst
A
0.50
0.014
0.025
0.012
0.247
A With all present: underlayment, cabinetry, shelving, paneling, and interior doors.
B Without underlayment
C Without panel 1 ing
0 Without underlayment or panelling
E Without doors
F Without underlayment or doors
G without panelling or doors
H Without underlayment, panelling and doors
- 35 -
-------
Initial
Formaldehyde
Concentration
(ppm)
0.45
0.4- -¦
0.35 -
0.3
0.25
0.2 -)
0.15-1
0.1 -I
0.05 H
Emission profile = low
Loading class = A
Home type = manufactured
VERSAR MATTHEWS HBF
0.25 Air change per hour
MODELS USED
VERSAR MATTHEWS HBF
0.75 Air changes per hour
Figure 2. Comparison of initial formaldehyde levels predicted oy three models
- 36 -
-------
4.2 Effect of Formaldehyde Emission Rates
The effect of varying the emission profile in three types of homes is
shown in Figure 3. For these model runs, the air exchange rate is
constant at 0.5 air changes/hour and full UF product loading is assumed.
In all three home types, the use of PF-substitutes decreases the mean
formaldehyde levels by approximately 93 percent.
4.3 Effect of Product Loading
As shown in Table 3, the product loading in all three types of homes
can vary greatly. Figures 4, 5, and 6 show the effects of different
loadings in manufactured homes, detached homes, and attached homes,
respectively. In the model runs represented by these figures, all
factors other than product loading were held constant.
These figures illustrate that the effects of multiple products in a
home are not necessarily additive. For example, in Figure 4, (initial
concentration in manufactured homes), adding only underlayment to the
loading class D home (i.e., going from class D to class C) increases the
initial concentration by 0.14 ppm. Adding only paneling to the class D
home (i.e., going from class D to class B) increases the initial
concentration by 0.25 ppm. Adding both underlayment and paneling to the
class D home (i.e., going from class D to class A) increases the initial
concentration by 0.29 ppm, not 0.39 as might be expected by adding the
increases predicted for underlayment and paneling alone.
4.4 Effect of Air Exchange Rates
Several model runs were designed to evaluate the effect of varying
the home's air exchange rate. For each type of home, air exchange rates
were varied from 0.25 to 1.00 air changes/hr, while all other factors
were held constant. Figures 7, 8, and 9 illustrate the results of these
runs. These figures show that, although increasing the air exchange rate
decreases the formaldehyde concentration, this relationship is not
- 37 -
-------
Initial
Formaldehyde
Concentration
(ppn)
0.35 -
0.25 -
0.15
0.05
t
12 3 4
Manufactured
Air exchange rate =0.5
Loading class = A
1 2 3
Detached
EMISSION PROFILE
4 12 3
Attached
Key for emission profiles
1 low
2 average
3 substituted
4 high
Mean
Formaldehyde
Concentration
(ppm)
0,2 ~T
0.19 -i
0.18 -I
0.17 -I
0.16
0.15 -j
0 14
0.13
0.1
0 09
0.08
0.07
0.06
0.05
0 04
0.03
0.02
0.01
0
1
'A
n
j
'/ A
'/A
1
A A
/ A
AV\
'4
/ A\
yAs
//A
*V/i
\/ /,
1 //
Al>
"'''I
y'A
a
S\
, A
I A
\/ A
A A
' / s
A
-------
Initial
Formaldehyde
Concentration
(ppm)
Mean
Formaldehyde
Concentration
(ppm)
0.35 -/
0.3 -
/
0.25
/
V/AA's
0.2 —i/ ' x /
' ¦¦ S
f'/A///,
X / '/'>
¦¦/¦A//A
y '¦ /, /
r-7-v-7'
-r-'—S-X
'
¦' A
A /
/ V
/ '/
Loading class
Figure 4. Effect of product loading on predicted initial and mean
formaldehyde levels in manufactured homes
- 39 -
-------
Initial
Formaldehyde
Concentration
(ppm)
Loading class:
A with al1 present
B w/o underlayment
C w/o paneling
D w/o underlayment
or paneling
B C D E
Loading class
E w/o doors
F w/o underlayment or doors
G w/o paneling or doors
H w/o underlayment, paneling
and doors
Air exchange rate = 0.5
Emission profile = Average
0.09 -
Mean
Formaldehyde
Concentrati on
(ppm)
0 08
0.07 -/ ¦ , /
0.06 -
0.05
0.04 -
0 03
/ '
/'
7Z
"///a
// //
/
/
/ '' ' /
/ /i
v
y // /
¦'A
'//
'///
/ / / '
///A
// / /
r'
/
/•
' /
/ ' /
v .' ¦ /
y
/
y ¦
0 02
/
//,
/ /
< •' /
/ /
/
/ / s
/ /
/
J
\
\
\
0.0'
~
/
/ / '
V'
'V /
/
/ / '
/
' ' /'
r'
/
/
/
/
/ <
s /
B
H
Loading class
Figure 5. Effect of product loading on predicted initial and mean
formaldehyde levels in detached homes
-------
0.26
Initial
Formaldehyde
Concentration
(ppm)
Loading class:
A with all present
B w/o underlayment
C w/o paneling
D w/o underlayment
or paneling
D E
Loading class
E w/o doors
F w/o underlayment or doors
G w/o paneling or doors
Air exchange rate = 0.5
Emission profile = Average
H w/o un
an
ayment, paneling
Mean
Formaldehyde
Concentration
(ppm)
0.09 -
°-08 ~Y/r7~/^
Y/'/S
0.07 -V // /
V/''/
0.06
Y/ / s
0 05
V ¦ , /
oo,-a ;v
/ / v / / /I
r / / ^
aa/
/ / / /
Va
7 ^
0.03
0 02 -
0.0 i -
->/¦¦//
¦' /
A ¦ 'A
V / '
' A
'/ //
l/ / , ' /
/
/'A' ¦
> / ' /'
/
// , / .
/
\
\
A
\
\
\
1
/
/ / -
/ ' A
/
' A
/V
r
A
'
77-
'//
/
/,
////
'A
A/
y/
v / / /
A: v
V //A
/, ¦' ¦¦ /
' ' / ,
A A / z1
' /"
/"
/ /
' *
/ /
/
' /
/ / / /
/
/
/
/ '
s ¦ , /
/
A
, /
S ¦' s
/'
/
y A
/
/
, /
A '
y' '
/
/ /
y ' A
/
' / / /
~ /
A B C 0 E F
Loading class
Figure 6. Effect of product loading on predicted
formaldehyde levels in attached homes
. /II -
G H
initial and mean
-------
Initial
Formaldehyde
Concentration
(ppm)
0.2 H
0.25
0.50
Air Exchange Rate
0.75
1
1.00
Emission profile = average
Loading class = A
Mean
Formaldehyde
Concentration
(ppm)
0.25
0 50 0.75
Air Exchange Rate
.00
Figure 7. Effect of air exchange rate on predicted initial and mean
formaldehyde levels in manufactured homes
- 42 -
-------
Initial
Formaldehyde
Concentration
(ppm)
1.00
Air Exchange Rate
Emission profile - average
Loading class = A
Mean
Formaldehyde
Concentrati on
(ppm)
Air Exchange Rate
Figure 8. Effect of air exchange rate on predicted initial and mean
formaldehyde levels in detached homes
- 43 -
-------
Initial
Formaldehyde
Concentration
ippmj
0.29 - s .
0.28 -
0.27 -
0.26 -
0.25 -
0.24 -
0.23 -
0.22 -
0.21
0.2 -
0.19 -
0.18
0.17 -j
0.16
0.15 -i
0.14 -
0.13 -
0.12 -
0.1 1 -
0.1 -j—
0.25
V
0.50
0.75
1.00
Air Exchange Rate
Emission profile = average
Loading class = A
Mean
Formaldehyde
Concentration
(ppm)
0.2
0 19-
o 18
0 17 -
0.16 -
0 15-
0.-4 -
0.13 -j
0 12-
0 11 - '
0 1 -
0.09 -
0.08 -j
0.0" -
0 06 -
0.05
0 04 -
0.03 -
0.02 -
0.01 -
0
0 25
0.50
0 75
Figure 9.
Air Exchange Rate
Effect of air exchange rate on predicted initial and mean
formaldehyde levels in attached homes
- 44 -
-------
linear. The same unit increase in air exchange rate results in a greater
decrease in formaldehyde concentration at low air exchange rates than at
higher air exchange rates. For example, in the case of manufactured
homes, increasing the air exchange rate from 0.25 to 0.50, decreased the
mean concentration by approximately 21 percent; however, increasing the
air exchange rate from 0.75 to 1.00 resulted in a 14 percent decrease in
mean concentration.
In interpreting and applying these model results, caution is again
recommended. As stated previously, this model has not been validated for
predicting formaldehyde levels in actual homes. Details of the model's
limitations were presented in Section 2.4. If, however, any one factor
(such as ventilation) is not precisely represented in the model,
resultant errors will probably be systematic (rather than random),
allowing results from different scenarios to be compared with each other.
- 45 -
-------
5. REFERENCES
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-------
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Singh J, Walcott R, St. Pierre C, et al. 1982. Clayton Environmental
Consultants, Inc. Evaluation of formaldehyde problem in mobile
homes—testing and evaluation. Final Report. Washington, DC:
Department of Housing and Urban Development Contract No. HC-5222.
Versar Inc. 1986. Formaldehyde exposure in residential settings:
sources, levels, and effectiveness of control options. Washington, DC:
U.S. Environmental Protection Agency, Office of Toxic Substances.
Contract No. 68-02-3968.
- 47 -
-------
APPENDIX A
COMPUTER PROGRAM FOR VERSAR MODEL
-------
PROGRAM FORMALD1 APPENDIX A
***** **************************$**********
** PROGRAM FOR TOM CHAMBERS TO COMPUTE
** FORMALDEHYDE CONCENTRATIONS AND
** EXPOSURES IN MOBILE HOMES
******************************************
** THIS PROGRAM WAS DEVELOPED BY
** SHIV KRISHNAN FGR TASK # 867.14.
** DATE : AUGUST 13, 1984.
** MODIFIED 9/10/84, B. WOODCOCK, PRODUCT U 20 ADDED
** 12/13/84 PRODUCT U 21 ADDED
** 4/25/85, S. KRISHNAN, REVI53CN5
** MODIFIED 5/21/85 B. WOODCOCK, ACOED BACKGROUND CONCENTRE 1ICN
** MODIFIED 6/18/85 J. EDMISTON, REVISIONS FOR SLOPE DATA
** MODIFIED 7/01/85 J. EDMISTON, REVISIONS REGULATING CONM/>
** MODIFIED 9/16/85 J. EDMISTON, REVISED VALUE5 REGULATING CCf^MAX
**«>***4:t****$t*«***«**************
PARAMETER (NPR0D=31)
DIMENSION SLOPEtNPROD ) ,Y INTCPT (NPRCC ) , INOEX( NPfiOD ) , A R E /
-------
i'MAX HUC PtfU' , ' MAX" HUD 'PBT' MAX HuC PNPR'S 'PAX" HUD "P NX •"/
** REAU INPUTS INTERACTIVELY
TYPE *,'ENTER A TITLE FOR THIS RUN (60 CHARACTERS) ¦
ACCEPT *,TITLE
TYPE *, 'ENTER ANY SCENARIO IDENTIFIER 140 CHARACTERS)'
ACCEPT *,SCENARIO
TIME = 90. * 24.
TYPE *,'ENTER HOME DIMENSIONS (HEIGHT, LENGTH, WIDTH Ih FEET)
ACCEPT *, HT,LENGTH,WIDTH
V = HT * LENGTH « WIDTH * (0.3048 ** 3)
TYPE +, 'ENTER MIXING FACTOR (RANGE = 0.1 TO 0.33)'
TYPE », 1 - (DEFAULT = 0.2)'
ACCEPT *, MIXFAC
IF (MIXFAC .LE. 0.0 .OR. MIXFAC .GT. 1.0) THEN
MIXFAC = 0.2
ENDIF
TYPE *,'ENTER AIR EXCHANGE RATE (RANGE = 0.2 TO 1.0)'
TYPE *,' - (DEFAULT = 0.25)'
ACCEPT *, AIRCH
IF (AIR Ch .LE. 0.0) THEN
AIRCH = 0.35
ENDIF
KRATE = AIRCH * MIXFAC
TYPE *, 1 ENTER BACKGROUND CONCENTRATION - PPM'
ACCEPT * , BACKGROUND
IF (BACKGROUND .LE. 0.) THEN
BACKGROUND = 0.01
ENDIF
TYPE ~,'HOw MANY FORMALDEHYDE RELEASING PRODUCTS DO YOl'
TYPE *,'WANT TO CONSIDER INSIDE THE MOEILE HOME ? '
ACCEPT *, I PRODUCT
DO 100
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
I = 1, IPRODUCT
*, 'ENTER THE INDICES AND PRCCUCT AREA (SO,
'Product Index Product
*, 'PARTICLE BOARD
«, 'PCB *1 1
* , ' P C'B # 2 2
*, 'PCB * 3 3
~t'AVG. PBU 22
~,'PBU 3 # 3 b
*,'INDUSTRIAL PARTICLE HOARD'
* » ' P BI 3 * 2 6
~,'AYG. P BI 23
FEET) '
Into'
PLYWOOD
PANPR #
PANPR U
PLYWOGC
PNP 2 9
*, 'PARTICLE BOARD UNDERLAYMENT« AVG
1 # 4 4 PNP 3 #
PNP 3 S
PLYWOOD
PND 1 K
~i'MED. DENS. FIBER BOARD*** PNC 1 #
~,'rtOF 1 * 5 7 PND 3 *
PANELING
2
3
PANELING
4
, PNP
1.2
1,2
PANELING
1,2
1,2
5
* ,'rtDF 3*5
8
AVG. PNC
IFF INT )
] 1 '
12 ' •
I F / F E P )
12 '
It '
J4 '
II '
(CCfES.
]( '
11 '
]£ '
il '
-------
*T Yp-rrr1 PL?wC0D TANEL ING TpRINT)*V* A VG. MDF cL
TYPE *,'PNPR 2 # 3 9 PAND #1 J«
TYPE *,'PNPR 3 * 3 10 INPLY PF 1 2C
TYPE *,'AVG. PNPR 25 HDB-21 21
TYPE * , 'MAX HUD PBU 26 MAX HUD PBI 2S
TYPE *9 'MAX HUD PNPR 30 NAX HUC PNC 31
ACCEPT *,IND,AREA ( INO)
AREA (IND) = AREA(IND) * 0.3048 * C.3048
INDEX(1NU) = IND
100 CONTINIE
~* COMPUTE INITIAL FORMALDEHYDE EMISSION RATE (MG/HR )
DO 101 J = 1 * N PROD
IF (J .EO. INDEX(J)) THEN
GTEMP = YINTCPTlJ) * A REA(J)
GINIT = GINIT + GTEKP
END IF
101 CONTINIE
TYPE *»'ENTER INITIAL FORMALDEHYDE CCNCENTRATICN INSIDE1
TYPE * i 'MOBILE HOME (PARTS PER MILLICN)'
TYPE *,' •
ACCEPT * ,CONINIT
** CONVERT CONINIT FROM PPM TO MG/CU.M
CONINIT = CON IM T * 1.24
IF (COMMT .LE. 0.0) THEN
COMNIT = 0.0
END IF
****** ft**********,************
** COMPUTE CONCENTRATION FOR THE FIRST ECUILIBRIUM PERIOD.
** BASED ON THE CONCENTRATION RECOMPUTE EMISSION RATES.
** COMPUTE CONCENTRATIONS FOR THE NEXT ECUILIBRIUM PERIOD.
+* REPEAT THE PROCESS UNTIL THE TIMEFRAME IS COMPLETED.
****** 4*4444****4***4***44**4*
id R ITE 17,480) TITLE,SCENARIO
DO 210 K = 1,24
LOOP = INT (TIME/K)
KOUNIER = 0
CO = CCMNIT
G = GINIT
OLDAVG = 1.0
T1 = K/l.
DO 20C I = 1,LOOP
AVGCGNC = 1./T1 * ( G * T1 / (V»KRATE ) ) +
1 1./T1 * ( G / (V*KR AT E ) - CC ) *
i (< EXP(-KRA T E * T1) - 1.) / KRATE)
AVGPPf = AVGCONC / 1.24
I
G = C.C
00 3C0 J = 1, NPROD
IF (J .EQ. INDEX(J)) THEN
EMSRATE = SLOP E ( J) * AVGPPM * YINTCPT(J)
EMISRaTE = EMISRATE * AREA(J)
IF (tMISMTE .LT. 0.0) THEN
-------
EfUSkXTE' = u.u
END IF
G = EMISRATE + G
END IF
300 CONTINUE
*****444444*4**4*44***44***4*******4**
** COMPARE THE NEW AND THE OLD CONCENTRATIONS. IF THEY A ft
*+ ACCURATE UPTO 6 SIGNIFICANT DIGITS FOR 50 CCNSECUTIVE
** COMPARISONS t THEN STOP CALCULATION AND GO TO NEXT
<¦* EQUILIBRIUM TIME.
**4*44****4444**4**4*****************
ACCURATE = (AVGPPM - OLDAVGJ/AVGPPf/lGOOOCC.
OLDAVG = AVGPPM
IF (ACCURATE -GT. -1. .AND. ACCURATE .LT. l.C) THEN
KCUNTER = KOUNTER ~ 1
ELSE
KCUNTER = 0
END IF
CO = AVGCONC
IF (KCUNTER .GT. 50) THEN
GOTO 205
END IF
200 CONTINUE
205 CONTINUE
PPM(K) = AVGPPM
EMISSICN(K) = G
IF (KOUNTER .GE. 50) THEN
EQUILIB(K) = (I - 11) * K /24.
ELSE
EQUILIB(K) = (1-1) * K / 24.
ENDIF
480 FORMAT (' 1' ,//////T10 * ' EP A / VERSAR FORMALCEhYDE EXPCSISE STU-DY1
$ //T10,C60//T10,C40//)
WRITE (7,490) K,EGUILIB(K) ,PPM(K )
490 FORMAT (T10»*EQUILIBRIUM (1,T24,12 , T26 , ' HOUR) WAS RE/CFEC IN',
% F7 .1,T57,' DAYS »//
S T1Q , 'ECUILIBRIUM CONCENTRATION ISf*T40,F10.4 ,T52 , 'PPf ' I ) )
210 CONTINUE
WRITE (7,480) TITLE,SCENAR10
WRITE (7,500) V,MIXFAC,AIRCH,IPRQDUCT
500 FORMAT (///
i T10 , * ROOM VGLUME = ',T4d,F10.2,Tfc1, •CUB IC METERS*//
% T10, 'NCN-IDEAL MIXING FACTOR = ST5C,F5.2//
1 T10, ' A IR EXCHANGE RATE (PER HOUR) = ',T5C,F5.2//
$ T10,'NUMBER OF PRODUCTS CONSIDEREC = ',T5C,I5//1
WRITE (7,550)
550 FORMAT ( / / T10,1 P ROOU CT S CONSIDERED • ,T55 » 'AREA (SC. FEED*/
S T10,' ' ,T 55 » ' «/)
DO 560 JJ = 1, NPROD
IF (JJ .EQ. INDEX(J J ) ) THEN
WRITE ( 7,570 ) PRDDICT{J J),AREA{J J)/{.304e*.3043 >
ENDIF
-------
DfcTO CONTlNCr"
570 FORMAT (/T10 , C40,T55,F11.2)
^ + 4$matm + m
n ** COMPUTE ThE MINIMUM TIME REQUIRED FCR EQUILIBRIUM.
** SUBSTITUTE THE CCNCENTRATI ON AND EMISSION RATE
_ ** VALUES AT EQUILIBRIUM.
C **$*~~****~ ~~$***~** 4 $***~ +
EQMIN = 100000.
DO 5*30 K = 1,24
IF (EQUILIB(K) .LT. EQMIN) THE N
ECMIN = EQUILIE(K)
EMITMIN = EMISSICNIK)
PPMIN = PPM(K)
END IF
590 CONTINUE
WRITE (7,600) GINIT,CGNINIT/1.24,ECMIN,PPMIN,EMITMIN
600 FORMAT (//T10,'INITIAL EMISSION RATE = ',T60,F7.3,
% T68,'MG/HOUR'//
i T10,'INITIAL FORMALDEHYDE CONCENTRATION - ',T60,F7.3,
% T68, ' PPM'//
$ T10,'CONCENTRATION ECU IL I B R IUM WAS PEACHED 11> • ,
$ T60,F7.1,T68,'DAYS'/
$ //T10,'CONCENTRATION WHEN ECIILIBRIUM WAS ',T45,
$ 'ACHIEVED = ',T60,F7.3,T68,'PPM'///
$ T10, 'FORMALDEHYDE EMISSION RATE In HEN EQUILIBRIUM WAS'/
$ T10,'ACHIEVED = ' ,T60 ,F7 . 3 , T68 , ' MG/HOUR • //)
TYPE *,'ENTER NUMBER OF YEARS FOR EXPOSURE'
ACCEPT + , YEAREXP
TYPE *,'ENTER INHALATION RATE (CU. METERS PER DAY)'
TYPE ~,' (20 - 24 CU.MET / DAY), - DEFAULT 24 CU.MET / CM'
ACCEPT ~¦,RATE
IF (RATE .LE. 0.) THEN
RATE = 24.
EN D IF
C USE DECAY EQUATION Y = BACKGRCUND ¦» A * EXP (-B * T)
A = .5C4
8 = .0CC65
T = YEAREXP * 365
Y = BACKGROUND ~ (A * EXP(-B ~ T))
TYPE »,'BACKGROUND CONC ',BACKGROUND
CO NEXPPM = PPMIN / 0.0007 / (YEAREXP » 365.) *
S ( 1. - Y)
CONMAX = PPMIN
** BELOW SLERCUTINE INSERTED BY JWE ON 7/1/85
** HAVE TO ECU INITIAL CONC. (CONINIT) TC MAX CCNC. (CONMA))
C ** IN THE SAME UNITS (PPM)
IF (CONMAX .LT. (CUNINIT / 1.24)) CCNMAX = CONINIT / 1.2*
IF ((BACKGROUND .EU. . C 2 5 ) . AND . ( CO NM A X .GT. . 2 fc <5) ) GCTt 6 CC
IF ((BACKGROUND .EG. .011) .AND.(CONMAX .GT. .IIS)) GOTC ECO
NUMDAYS = (ALOG(CONMAX) - ALCG(BACKGROUND ) ) / .00065
GAVETCBACK = (CONMAX*((-(EXP(-.OCC65*NUM0AYS))/.0006 J )
u + 1536)) / NUMDAYS
CONEXPPM = ((NUMDAYS * OAVETOBACK) +
£ ((3650 - NUMDAYS) * BACKGROUND ) ) / 365C
** END OF SUBROUTINE J*E 7/1/85
300 CO.NMIN = PPMIN * Y
EXPOSURE = CONEXPPM * 1.24 * RATE
EXPOSURE IS IN MG/OAY
-------
1000
EXPOSURE = EXPOSURE * .6667
WRITE (7,430) TITLE,SCENAR10
WRITE (7,1000) YEAREXP,C0NMAX»C0NMIh,CCNEXPPM»RATE»EXPC5lFE
FORMAT (///
TlOi'EXPOSURE PERIOD IS ASSUMED TO
PERIOO QF EXPOSURE,1
8E',T«4,F5.1,T50 » 'YEARS'//
'/
» /
CONCENTRATION (PPM) = ',T45,F7.3//
CONCENTRATION (PPM) = C,T45,F7.3//
DAILY CONCENTRATION (PPM) = *,T52,F7.3/y
DAILY INHALATION RATE (CO.MET / DAY) = «
TlO,•DURING THE
TlO,'
/T15,'MAXIMUM
T15»'MINIMUM
T15,'AVERAGE
T15,'AVERAGE
F7.2//
T15» 'AVERAGE DAILY EXPOSURE (MILLIGRAMS PER DAY) = «,Tt2,F7.3)
STOP
END
i Tfc2
-------
APPENDIX B
NAHB BUILDER PRACTICES SURVEY RESULTS
-------
APPENDIX B
NAHB Research Foundation, Inc.
Builder Practices Survey
1984 Construction
LOOR SYSTEM - Single Family Detached Units
verage floor area for single family detached units constructed in 1984
as 1,684 square feet.
^ingle family detached housing starts in 1984 was 576,670 units,
loor systems in 1984 single family detached units:
Survey
Wood floor svstem Sample Percent
'"one (slab on grade) 12,672 units 21.8%
ouble layer system 7,481 12.9
ingle layer system 22,221 38.2
Single layer system with
double in kitchen & bath 15,369 26.4
>ther 366 0.6
TOTALS 58,109 units 99.9%
Jquare feet (x 1000) of l/2" equivalent particleboard used in single
family detached unit floor systems in 1984:
Single Single layer
Installed Double laver systems layer with double in
:nickness Underlavzient Sheathma systems kitchen & bath Totals
1/4" 323 - 117 309 749
3/8" 5,323 - 5,971 3,722 15,016
1/2" 24,703 12,464 792 1,977 39,936
5/8" 74,661 1,0£3 7,111 732 83,587
TOTAL 139,288
3-1
-------
1. Double layer floor systems - installed in 12.9 or 113,090
SFD units in 1984.
Particleboard underlayment was used in 48.4% or 54,735
units with double layer floor system:
Unit
Installed
Incidence
Area
No. of
hickness
i i
( sq. ft. )
units
1/4"
13 0.7
1684
54,735
3/8"
141 7.7
1684
54,735
1 2"
487 26.8
1684
54,735
5/8"
1179 64.8
1684
54,735
1/2" eouiv. PB (xlOOO)
0.50 323
0.75 5,323
1.00 24,703
1.25 74,661
Particleboard sheathing was used in 7.0% or 7,916 units
with double layer floor system:
Unit
nstalled
Incidence
Area
No. of
Convert to
Qty. of 1/2
hickness
* %
(so. ft. )
units
1/2" eauiv
. PB (xlOOO)
1/4"
_ _
1684
7916
0. 50
—,
3/8"
-
1684
7916
0.75
-
1/2"
245 93.5
1664
7916
1.00
12,464
5/8"
17 6.5
1684
7916
1.25
1,083
!. Single
laver floor
systems
- installed in 38.2%
or 334,888
SFD units in 1984.
Particleboard used
in 2.6%
of the sir
igle layer
floor systems
or 8,707 units:
Unit
Installed
Incidence
Area
No. of
Convert to
Qty. of 1/2
thi ckness
•If
\rfP
(sc. ft.)
units
1/2" eouiv
. PB (xlOOO)
1/4"
4 1.6
1684
8707
0.50
117
3/8"
140 54.3
1684
8707
0.75
5,971
1/2"
14 5.4
1684
8707
1.00
792
5/8"
100 38.8
16S4
8707
1.25
7,111
B-2
-------
5. Single layer floor systems with double layer installed in
kitchen and bath area - installed in 26.4% or 231,441 SFD
units in 1984.
Particleboard underlayment was used in 18.5% or 42,816 of
these units.
Underlayment area based on assumed kitchen dimension of
9x12 and two bathrooms with dimensions of 5x8 or a combined
total area of 188 square feet. All subsequent calculations
based on 190 square feet.
nstalled
thickness
Incidence
* \
Unit
Area
( sa. ft. )
No. of
units
Convert to
1/2" ecuiv.
Qty.
PB
of 1/2"
(xlOOU)
1/4"
171 7.6
190
42,816
0.50
309
3/8"
1380 61.0
190
42,816
0.75
3, 722
1/2"
551 24.3
190
42,816
1.00
1,977
5/8"
162 7.2
190
42,816
1.25
732
B-3
-------
FLOOR SYSTEM - Single Family Attached Units
Average finished floor area for single family attached units 1984 was
Single family attached housing units started
in 1984
Floor systems in 1984 single
family attached
uni ts :
Survey
Wood floor svstem
Sample
Per cent
None (slab on grade)
5,451 units
15 .7%
Double layer system
3,416
9.9
Single layer system
18,785
54.3
Single layer system with
double in kitchen & bath
6,617
19.1
Other
839
2.0
TOTALS
35,462 units
100.0%
Square fee
t (x 1000)
of
1/2" equivalent par
ticleboard used
m single
family att
ached unit
floor systems
in 1984:
Single
Single layer
Installed
Double laver
svstems
layer
with double in
thickness
Underlavment
Sheathinq
svstems
kitchen & bath
Totals
1/4"
56
56
3/8"
1, €53
-
-
267
1, 940
1/2"
10,799
7,495
-
260
18,554
5/8"
12,163
-
-
132
12,295
3/4"
-
-
4, 050
-
4, 050
TOTAL 36,895
B-4
-------
1. Double
layer floor
systems
- installed in 9.91 or 36,563 SFA
units
in 1984
Particleboard underlayment
was used
in 50.8% of
the double
layer
floor systems or 18,574 units.
Unit
Installed
Incidence
Area
No. of
Convert to
Qty. of 1/2"
thickness
# %
( sq . f t. )
units
1/2" equiv.
PB (xlOOO)
1/4"
0 -
1224
18,574
0.50
3/8"
92 9.7
1224
18,574
0.75
1,653
1/2"
449 47.5
1224
18,574
1. 00
10,799
5/8"
405 42.8
1224
18,574
1.25
12,163
3/4"
0 -
1224
18,574
1.50
-
Particleboard sheathing was
used in
16.7% of the
double
layer
floor systems or 6,123 units.
Unit
Installed
Incidence
Area
No. of
Convert to
Qty. of 1/2"
thickness
* %
(sc. ft.)
units
1/2" eauiv.
PB (xlOOO)
1/4"
1224
6123
0.50
3/8"
-
1224
6123
0.75
-
1/2"
312 100
1224
6123
1.00
7,495
5/8"
-
1224
6123
1.25
-
3/4"
- -
1224
6123
1.50
—
2. Single
i laver floor
systems
- installed in 54.3%
or 200,540
SFA units in 19S4.
Particleboard used
in 1.1%
of the single layer f
loor systens
or 2,206 units:
Unit
Installed
Incidence
Area
No. of
Convert to
Qty. of 1/2"
thickness
%
(sc. ft. )
units
1/2" eauiv.
PB (xlOOO)
1/4"
— _
1224
2206
0.50
3/8"
-
1224
2206
0.75
-
1/2"
-
1224
2206
1.00
-
5/8"
-
1224
2206
1.25
4, 050
3/4"
56 100
1224
2206
1.50
-
B-5
-------
3. Single layer floor systems with double layer installed in
kitchen and bath area - installed in 19.1% or 43,986 SFA
units in 1984.
Particleboard underlayment was used in 10.3% of the
systems in the kitchen/bath area or 4,530 units.
Underlayment area based on assumed kitchen dimension of
9x12 and two bathrooms with dimensions of 5x8 for a combined
total area of 188 square feet. All subsequent calculations
based on 190 square feet.
Unit
installed
Incidence
Area
No. of
Convert to
Qty. of 1/2"
thickness
£ i
( sa. ft. )
units
1/2" ec'jiv.
PB (xlOOO )
1/4"
56 13.0
190
4530
0.50
56
3/8"
191 44.4
190
4530
0.75
287
1/2"
130 30.2
190
4530
1. 00
260
5/8"
53 12.3
190
4530
1.25
132
3/4"
-
190
4530
1. 50
-
B-6
-------
ANELING
Single Single
Family Family
Detached Attached
'ercent of Homes with paneling 12.2% 6.3%
Amount of Paneling Per Unit (sq.ft.)
Plywood 347 218
Hardboard, flush 37 48
Particleboard 1 23
Pre-aecorated gypsum 3 9
Unfinished boards 55 24
Other & not reported 15 32
B-7
-------
CABINETS
Number of cabinets
In kitchen
As vanities
In other rooms
Single Family Single Family
detached attached
11.0
2.5
0.7
10.1
2.3
0.7
-abinet Door Front Material
High pressure laminate veneer,
plywood
High pressure laminate veneer,
particleboard
Wood veneer, plywood
Solid wood
Metal
Other & not reported
Single Family Single Family
detached attached
1%
16
26
48
1
5
2%
24
30
43
1
1
Countertpp Area
The 11 kitchen cabinets shown above for single family detached units
include.both wall and base units. The most likely distribution of'
these 11 units is 6 wall units and 5 base units. Further, they are
most likely arranged in an L-shape. The most common cabinet widths
18, 24, 30, and 36 inches. The base cabinets stand 34.5 inches high
and are 24-inches deep. The counter top is 25-inches deep providing
1-inch overhang at the front.
In order to estimate counter top area, assume four 24 inch base
cabinets plus two 36-inch base cabinets, one under the sink and one
under the cook top. This comes to 14 linear feet of base cabinets.
Multiplying by the 25-inch counter depth yields 29.2 square feet. T
this must be added 4.3 souare feet of corner area.
The total counter top surface area would be 33.5 square feet.
B-8
-------
TNTERIOR DOORS
Single Single
Family Family
Detached Attached
dumber of Interior Doors
Passage doors 10.5 8.8
Closet-type doors 5.3 4.4
Total 15.8 13.2
'assage Door Types
Wood, flush, hollow care 35% 33%
Wood, flush, solid - 3
Wood, solid panel 7 4
Hardboard, smooth 24 29
Hardboard, textured 9 9
Hardboard, molded panel 21 20
Plastic
Other & not reported 3 2
Closet Door Types
Wood 40% 35%
Vinyl wrapped wood 6 5
Hardboard, smooth 3. 5
Hardboard, textured 8 6
Hardboard, molded panel 27 26
Aluminum 2 2
Steel 6 12
Plastic 1 1
Other & not reported 7 8
Closet Door Design
Bifolc, single door 7% 8%
Bifold, double door 25 27
Bipass, pairs 23 23
Accordian fold
Same as passage doors 45 41
Other & not reported
B-9
-------
TLOSET SHELVING
Single Single
Family Family
Detached Attached
Material Type
No shelving
Wood
Particleboard
Steel
27
47
4
18
4%
19
46
6
26
3%
Vinyl coated wire
Other
Note: Closet shelving is typically 12-inches deep.
The width of a typical closet in a second or third
bedroom or entryway closet is 46-inches. A master
bedroom would typically have twice this closet space
either divided into two separate closets or in one
oversized closet.
Linen closets are more typically in the 18-inch to
24-inch width range and are equipped with 3 to 4
shelves.
B-10
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APPENDIX C
DETAILED CALCULATIONS ON WOOD PRODUCTS REQUIREMENTS
FOR CABINETS AND DOORS IN MANUFACTURED HOMES
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Source: ICF 1986a.
APPENDIX C
DETAILED CALCULATIONS ON WOOD PRODUCTS REQUIREMENTS
FOR CABINETS AND DOORS
a. Kitchen Base Cabinets:
Dimensions of cabinet as stated in the figure; roof and bottom
of cabinets made of particleboard and the doors are made of
MDF; all hardwood plywood used is of 1/4" thickness. There-
fore, hardwood plywood required:
((24 x 35)
((35 x 30)
(30 x 6) x
(24 x 6) x
(24 x 30)
x
X
2
2
x 1
2)
1)
m =
in2 =
Particle board required:
MDF required
11.66 ft2
7.29 ft2
2.5
2.0
5.0
26.45
((24 x 30) x 2) in2 = 10 ft2
((35 x 30) x 1) in2 = 7.29 ft:
b. Kitchen Wall Cabinets:
Dimensions of cabinet as stated in the figure. Roof and
bottom are made of particleboard and all doors are made of
MDF; all hardwood plywood used is of 1/4" thickness. There-
fore, hardwood plywood required:
((30
((30
x 30) x 1)
x 12) x 2)
in2 = 6.25 ft5
0 ft5
in2 =
11.25 ft'
Particleboard required:
MDF required
(f 30 x 12) x 2UnJ = 5 0 ft2
((30 x 30) x 1) in2 =6.25 ft2
C-l
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c. Vanity Cabinets:
Dimensions of cabinet as stated in the figure. Roof and
bottom are made of particleboard all doors are made of MDF
all hardwood plywood used is of 1/4" thickness. Therefore
hardwood plywood required:
((30 x 21) x 2) in2 = 8.75 ft2
((30 x 30) x 1) in2 = 6.25 ft2
15.00 ft2
Particleboard required: ((30 x 21) x 2) in2 = 8.75 ft2
MDF required : ((30 x 30) x 1) in2 = 6.25 ft2
Manufactured homes are assumed to have 8 kitchen cabinets
(4 wall cabinets and 4 base cabinets) and 1 vanity cabinet,
C-2
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APPENDIX D
METHODOLOGY FOR CALCULATION OF WOOD PRODUCT USE IN CABINETS
IN SINGLE FAMILY DETACHED AND ATTACHED HOMES
-------
Source: ICF 1986b.
APPENDIX D
PART I: METHODOLOGY FOR CALCULATION OF WOOD PRODUCT
USE IN CABINETS IN SINGLE FAMILY DETACHED HOMES
A. KITCHEN BASE CABINETS: The typical single family detached house is
assumed to have 5 base cabinets with the dimensions shown in Figure 1 and
one cabinet below the sink of the size shown in Figure 2. This analysis
ignores cabinet drawers and assumes that the cour.tertop material also
serves as the roof of the cabinets.
The calculations below for wood product usage in cabinets assume a base
cabinet configuration shown in Figure 3. The countertop calculations are
done first followed by the estimation for the cabinets.
(a) Countertop: The countertop is assumed to be made of particleboard.
The area of the countertop excluding the corner area '3' in Figure 3
is as follows:
= [(2.5 + 2.5 + 2.5 + 2.5) x (25/12)] sq. ft.
= 20.83 sq. ft.
Area of corner area '3' = [(25/12) x (25/12)] sq. ft.
= 4.34 sq. ft.
Area of countertop = (20.83 + 4.34) sq. ft.
= 25.17 sq. ft.
(b) Base Cabinets: Because the roof (or top) of all the cabinets is
assumed to be the countertop only the wood products used in the
bottom, sides, and back of the cabinets need to be calculated.
Cabinets 1 and 2 (Figure 3) will have one side common. Cabinet 3
(i.e., the corner cabinet) will not have a door and will be
accessible only through the door of cabinet 4. Therefore there will
be no partition between cabinets 3 and 4.
(i) The total number of sides to be accounted for is 7 (seven)
Area of sides = [(24/12) x 34.5/12) x 7] sq. ft.
= 40.25 sq. ft.
(ii) The total area of the material used for the back of the
cabinets is the following:
= [(2.5 + 2.5 + 3 + 25/12 + 25/12 + 2.5 + 2.5)
x (34.5/12)] sq. ft.
= 49.35 sq. ft.
D-l
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Figure 1. Dimensions of kitchen
base cabinet
Figure 2. Dimensions of kitchen
base cabinet under the
sink
3o
COOK To?
Jo'
Figure 3. Top view of kitchen base cabinet configuration
D-2
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(iii) The total area of the material used for the bottom of the
cabinets is the following:
= [(2.5 + 2.5 + 2.5 + 2.5 + 3 + 2) x 24/12] sq. ft.
= 30 sq. ft.*
(iv) The total number of cabinet doors to be accounted for is 5,
because the cabinet under the sink will have a door even
though the corner cabinet will not.
Area of doors = [(34.5/12 x 2.5) x 4 + (34.5/12 x 3)] sq. ft.
= [28.75 + 8.625] sq. ft.
= 37.375 sq. ft.
(v) Material used
for a typical single family detached hous
follows:
(sq.
ft.)
Particleboard
Hardwood
1/2"
1/4" 1/2"
Countertop
25.17
Sides
40.25
Back
49.35
Bottom
30.00
Doors
5 .98
10.84
Total
110.5
40.25 10.84
Total 1/2" Equivalent
110.5
(20.13 + 10.84) = 30.97
NOTE: On an average 16 percent of single family detached
homes have cabinet doors made of particleboard and
29 percent have cabinet doors made of hardwood plywood
(NAHB 1986). Weighting the areas here will simplify
the scaling up of the areas to industrywide estimates.
B. KITCHEN WALL CABIN'ETS: The typical single family detached house is
assumed to have 6 wall cabinets of the dimensions shown in Figure 4 and
arranged in the configuration shown in Figure 5. It is assumed that there
are no cabinets over the sink and cooking range. It is also assumed that
cabinet 4 does not have a door and cabinets 4 and 5 (see Figure 5) have no
- This area is greater than the countertop area because of the extra
material added for the bottom on the cabinet below the sink.
D-3
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Figure 4. Dimensions of kitchen wall cabinet
Jr
-Jv
£
Figure 5. Top view of kitchen wall cabinet configuration in
single family detached home
D-4
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partition between each other so as to make the cabinet 4 area accessible
from the door for cabinet 5.
(a) Area of the top and bottom:
= [[(2 + 2 + 2 + 2 + 2+2) x 2] x 2] sq. ft.
= 48 sq. ft.
(b) Area of the sides: number of sides to be accounted for is 8:
Area of each side = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of sides = 40 sq. ft.
(c) Area of the cabinet backs: number of backs to be accounted for is 7:
Area of each back = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of back =7x5 sq. ft. = 35 sq. ft.
(d) Area of the doors: number of doors is 5
Area of each door = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of doors = 25 sq. ft.
(e) Material used in wall cabinets for typical single family detached
house is as follows:
(sq. ft.)
Particleboard Hardwood
1/2" 1/4" 1/2"
Top
24
Bottom
24
Back
35
Sides
40
Doors-
4
7.25
Total
87
40
7.25
Total 1/2" Equivalent
87
(20
+ 7.25) = 27.25
* NOTE: On an average sixteen percent of cabinet doors in
single family detached homes are of particleboard and
29 percent are made of hardwood plywood. Weighting the
areas here will simplify the scale up to industrywide
estimates.
D-5
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VANITY CABINETS: The total number of vanity cabinets in a single family
detached house is assumed to be 3.2. Each cabinet is assumed to have the
dimensions shown in Figure 6.
(a) Area of the top and bottom:
= [(30/12 x 21/12) x 2] x 3.2 cabinets
= 28.0 sq. ft.
(b) Area of the back:
= [(30/12 x 30/12)] x 3.2 cabinets
= 20.0 sq. ft.
(c) Area of sides:
= [(30/12 x 21/12) x 2] x 3.2 cabinets
= 28 sq. ft.
(d) Area of cabinet doors:
= [(30/12 x 30/12)] x 3.2 cabinets
= 20 sq. ft.
(e) Material used in vanity cabinets for a typical single family detache
house is as follows:
(sq. ft.)
Particleboard Hardwood
1/2" 1/4" 1/2'
Top 14
Bottom 14
Back 20
Sides 28
Doors- 3.2 5.8
Total 51.2 28 5.8
Total 1/2" Equivalent 51.2 (14 + 5.8) = 19.8
* NOTE: On an average sixteen percent of cabinet doors in
single family detached homes are of particleboard and
29 percent are made of hardwood plywood. Weighting the
areas herw ill simplify the scale up to industrywide
estimates.
D-6
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Figure 6. Dimensions of single family detached house
vanity cabinet
D-7
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D. CLOSET SHELVING: It is known (N'AHB 1986) that a single family detached
house has 5.3 closets on an average, i.e., between 5 and 6 closets per
house. Assuming that there are 5 closets in a house, viz., 1 entry way
closet, 2 bedroom closets, 1 master bedroom closet, and 1 linen closet,
the closet shelf space can be calculated.
(a) The entry way and bedroom closets are each assumed to have one shelf
12" deep and 48" wide. The area of the shelf therefore is A sq. ft.
Total shelf space area for the 3 closets thus is 12 sq. ft.
(b) The master bedroom closet is assumed to have twice the shelf space of
the bedroom closet. Assuming only 1 shelf, the area of the shelf is
8 sq. ft.
(c) The linen closet is assumed to have 3 shelves each with a dimension
of 18" x 24". Therefore total shelf area is 9 sq. ft.
(d) Total shelf space in a house with 5 closets is therefore 12 + 8 + 9 =
29 sq. ft. With an average of 5.3 closets the area would be (29 x
5.3/5) sq. ft. = 30.74 sq. ft.
(e) According to NAHB 47 percent of the 876,670 single family detached
houses used particleboard for shelving in 1984. Assuming 1/2"
particleboard is used, the amount cf particleboard used in 1984 was:
= (30.74 sq. ft. x _ 0.47 x 876,670)
= 12.666 (thousand sq. ft.)
D-8
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PART II. METHODOLOGY FOR CALCULATION OF WOOD PRODUCT
USE IN CABINETS IN SINGLE FAMILY ATTACHED HOUSES
KITCHEN BASE CABINETS: The typical single family attached house is
assumed to have the same number of base cabinets as the single family
detached house. The wood product usage therefore is single family
detached and single family attached houses is the same for cabinets except
for wood product use in cabinet doors.
The calculations for wood product use in cabinet sides, back, bottom, and
the countertop are the same as in the case of single family detached
houses. While the cabinet door area is the same as in single family
detached houses, the amount of particleboard and hardwood plywood used
differs from single family attached houses.
The table below summarizes the amount of particleboard and hardwood
plywood required for use in single family attached houses:
(sq. ft.)
Particleboard Hardwood
1/2" 1/4" 1/2"
Countertop 25.17
Sides 40.25
Back 49.35
Bottom 30.00
Doors- 8.97 11.96
Total 113.49 40.25 11.96
Total 1/2" Equivalent 113.5 (20.13 + 11.96) = 32.09
* Total door area = 37.375 sq. ft.
32 percent of doors on an average are made of hardwood ply-
wood and 24 percent of particleboard
Hardwood plywood (1/2") required: 11.96 sq. ft.
Particleboard (1/2") required : 8.97 sq. ft.
KITCHEN WALL CABINETS: The typical single family attached house is
assumed to have 5 wall cabinets of the dimensions shown in Figure 4 and
arranged in the configuration shown in Figure 7. It is assumed that there
are no cabinets over the sink and cooking range. It is also assumed that
cabinet 3 does not have a door and cabinets 3 and 4 have no partition
between each other so as to make the cabinet 3 area accessible from the
door for cabinet 4.
D-9
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S"
A
; v
Figure 7. Top view of kitchen wall cabinet configuration
in single family attached home
D-10
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(a) Area for the top and bottom:
= [[(2 +2+2+2+2) x 2] x 2] sq. ft.
= 40 sq. ft.
(b) Area of the sides:- number of sides to be accounted for is 7
Area of each side = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of sides = 35 sq. ft.
(c) Area of cabinet backs: number of backs to be accounted for is 6
Area of each back = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of cabinet backs = 30 sq. ft.
(d) Area of the doors: number of doors is 4
Area of each door = (2 x 2.5) sq. ft. = 5 sq. ft.
Total area of doors - 20 sq. ft.
(e) Material used in wall cabinets for typical single family attached
house is as follows:
(sq. ft.)
Particleboard Hardwood
1/2" 1/4" 1/2'
Top 20
Bottom 20
Back 30
Sides 35
Doors- 4.8 6.4
Total 74.8 35 6.4
Total 1/2" Equivalent 74.8 (17.5 + 6.4) = 23.9
Total door area is 20 sq. ft. Thirty-two percent of doors
on an average are made of hardwood plywood and 24 percent of
particleboard.
C. VANITY CABINETS: The total number of vanity cabinets in a single family
attached house is assumed to be 3.0. Each cabinet is assumed to have the
dimensions shown in Figure 6.
D-ll
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(a) Area of the top and bottom:
= [[(30/12 x 21/12) x 2] sq. ft./cabinet x 3 cabinets] sq. ft.
= 26.25 sq. ft.
(b) Area of the back:
= [(30/12 x 30/12)] sq. ft./cabinet x 3 cabinets
= 18.75 sq. ft.
(c) Area of sides:
= [(30/12 x 21/12) x 2 sides] sq. ft./cabinet x 3 cabinets
= 26.25 sq. ft.
(d) Area of cabinet doors:
= [(30/12 x 30/12)] sq. ft./cabinet x 3 cabinets
= 18.75 sq. ft.
(e) Material used in vanity cabinets for a typical single family attached
house is as follows:
(sq. ft.) .
Particleboard Hardwood
1/2" 1/4" 1/2"
Top and Bottom 26.25
Back 18.75
Sides 26.25
Doors* 4.50 6.0
Total 49.50 26.25 6.4
Total 1/2" Equivalent 49.50 (13.13 + 6.0) = 19.13
" Total door area is 18.75 sq. ft. Thirty-two percent of doors
are made of hardwood plywood, on an average while 24 percent
are made of particleboard.
D. CLOSET SHELVING: It is known (NAHB 1986) that a single family attached
house has 4.4 closets on an average, i.e., between 4 and 5 closets per
house. Using the calculations for total shelf space for single family
detached houses the material required for closet shelving in a single
family attached house can be estimated.
D-12
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Total shelf space for single family detached house (5 closet basis)
46 percent. Assuming 1/2" particleboard used in closets, the total
surface area of particleboad required can be estimated to be:
= (25.52 x 0.46 x 369,320) sq. ft.
= 4,335 (thousand sq. ft.)
D-13
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