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APPENDIX B ESTIMATING THE I~=T OF "SID~IAL ENI3~;Y~CONSERVATI~ ITS ON AIR QuArrlqr: A lIYPaDIErICAL CASE BYP=~IC" CASE ST=Y Two of the simplest and most cost-effective methods of reducing the energy consumption of a residence are to increase the insulation and to decrease air inf filtration. However, infiltration is she primary source of ventilation for residences, and reducing it may adversely affect air quality. Therefore, although caulking and weatherstripping ~ home may reduce energy consumption, they may also adversely affect the health and reduce the comfort of the occupants, unless alternative methods of controlling air quality are applied. Attempts to estimate the impact of residential energy-oonservation measures on air quality in the home and, consequently, on Me health and comfort of the residents are fraught with difficulty. Host troublesome in the issue of incommensurability: one cannot confidently compare the dollar costs of insulating a house and the associated reductions in fue' bills with the essentially nonquantifiable potential adverse effects ^ sir quality, health, and comfort. Furthermore, numerous assumpt; ns must be ~de. Some of the assumptions are relatively reliable; for example, demographic studies can provide evidence on average family size, lifestyle characteristics (such as smoking habits), and proportion of homes with ~ particular applim-.~e (such as a gas oven}. Other a~ssu~tions may be based on evidence and experience from the building trades--for example, the effectiveness of caulking the windows o~ a home. (engineering analyses of related interactions have bee;- performed. ~ Assumptions concerning the air quality in homes before and after the institution of energy- conservation measures can be based on evidence now being accumulated or on data already in hand. The following case study is an Invalidated example of the type of analysis that might be considered to assist in Eking decisions concerning energy conservation versus indoor air quality. It i8 proposed not as ~ solution to the analytic problem, but as an approach Subject to further study and refinement. As ~ discussion piece, it may assist in identifying the types of data needed for analysis, the Host appropriate mathematical models, and, most important. the assumptions S16
517 that may be validly applied. The reader Ant be aware that the models presented here have not been validated or tested in practical cases to determine their effectiveness in predicting results. This presentation i s for the purpose of illustration and discussion of a possible approach. EXISTING CONDITIONS To evaluate the possible impact of energy-conservation measures on ingle-family residences, conditions in a hypothetical home in central Iowa are simulated. It is a 15-yr-old, split-level house with a basement and an attached two-car garage. The total heated floor apace is 2,100 ft2, of which 700 ft2 is below grade. The house is of wood frame construction on a concrete-block foundation. It has insulation values of R7 in the walls and R11 in the ceilings, double-pane windows, and an infiltration rate of 0.8 air change per hour (ach) with windows and doors closed. The house is heated with a natural-gas, forced-air furnace and cooled with an electric central air-conditioning system. The house is occupied by a family of five: a father, who smokes cigarettes; his wife; her mother; and two children, 2 and 10 yr old. Appliances include a natural-gas stove, a gas clothes-dryer, an electric washing machine, an electric dishwasher, and a gas water-heater. All this is assumed to be fairly typical of a middle-class family in central Iowa. These conditions were used as the basis of an energy and Virtuality analysis of the home. The home was then reanalyzed for two mutually exclusive conservation measures, to determine the changes in energy consumption and air quality. The first measure was to reinsulate the walls to a value of Rll (1 additional inch of cellulose insulation) and the ceiling to Rl9 (2 additional inches of cellulose insulation); this measure was assumed to be accompanied by a reduction in the infiltration rate to 0.5 ach. The second measure was a higher insulation alternative in which the walls were increased to Rll and the ceiling to R30; the infiltration rate was assumed to decrease to 0.3 ach. Two other independent measures were analyzed for air~quality impact: the installation of an electronic air-cleaner and the cessation of cigarette-smoking. A summary of these alternatives is shown in Table B-1. The results of the energy-consumption and air-quality analyses for these alternatives were either directly or indirectly used in an economic model to determine the rate of return available to the homeowners for the various alteratives. CASE ANALYSIS Energy Consumption The annual heat loss and heat gain for the building were calculated from a simple steady-state model, with an overall heat-transfer coef f icient and annual degree-days for heating and cooling. The model was exercised for each of the three cases listed in Table B-2. Values
518 TABLE B-1 Summary of Scenario Analyzed tn Hypothetical Example Insulation Infiltration Air . Condition Case Wall Ceiling (ach) Cleaner Smoker . . , Existing P R-7 R-11 0.8 No Yes Alterna- A-1 R-ll R-19 0.5 No Yes tive A-2 R-11 R-19 0. 5 Yes Yes B-1 R-ll R-30 0.3 No Yes B-2 R-ll R-30 0. 3 Yes Yes B-3 R-ll R-30 0.3 No No TABLE B~2 Insulation Alternatlves R Value (h · ft2, °F/Btu) C_ Description ~ Cats Infiltration P Existing condition 7 11 O. ~ A Low insulation 11 19 0.5 B High insulation 11 30 O. 3
519 for the overall heat-transfer coef f icient (UA) were calculated in accordance with the method used by ASHAAE; 2 the results are listed in Table B-3. The annual degree-days~i are based on 30-yr averages for Des Moines, Iowa, and are based on 65°F. The values used for heating and cooling were 6, 710 and 928 degree~days/yr, respectively. These values for the overall heat-transfer coefficient and degree-days were used in the following equation to calculate the annual heat loss and heat gain: Q ~ 24 (UA) (DD), where Q ~ annual heat loss or heat gain {Btu), UA - overall heat-transfer coefficient (Btu/h - F), and DD - annual heating (cooling) degree-days. The results of these calculations are also listed in Table B-3. To estimate more accurately the energy consumed for heating. a seasonal furnace efficiency had to be determined. This efficiency depends on the steady-state efficiency of the furnace and the amount by which it is oversized. As the beating load is reduced, owing to the conservation measures, the seasonal furnace efficiency is also reduced--by approximately 2% for each 10% oversize increment (John E. Janssen, personal communication). The seasonal furnace efficiencies used for each of the cases are shown in Table B-4. By dividing these efficiencies into the heating loads, the energy input to the house can be calculated; by applying the energy conversion factor for natural gas {100,000 Btu/ccf}, the annual fuel consumption can be determined. These results are shown in Table B-4. The annual electric consumption for cooling is calculated from the following equation: Qelec ~ 1.3Q/(COP)~3,412), where Qelec electric-energy consumption (kWh), Q ~ sensible heat gain (Btu), 1.3 adjustment for latent load (assumed to be 30t of sensible load), COP seasonal chef f icient of performance (assumed to be 2 . 5 ), and 3 , 412 - conversion factor (Btu/kWh). The result" of these calculations are listed in Table B-5. Air Quality The air quality in the conditioned space was evaluated for the three cases and for the two independent measures (installation of an air-cleaner and cessation of cigarette-~moking). The contaminants evaluated were carbon monoxide, nitrogen dioxide, formaldehyde, radon, and Despicable suspended particles (RSP), which include dust and cigarette smoke. The models used in these evaluations are simple ones that have not been experimentally validated. There is ~ need to validate these findings not only experimentally, but also in practical test cases. The objective of there analyses was to determine the sensitivity of various parameters to the contaminant concentrations, and absolute values may only be assumed an approximate. General Models. The general model used to calculate the contaminant concentration profiles (except that for radons ts anon
520 TABLE B-3 Overall Heat-Transfer Coeff icients Heat Lose, Heat Gain, Case Description UA (Btu/h · OF) 10° Btu/yr 10° Btu/yr P Existing condition 737 il9 16 A Low insulation 582 94 13 B High insulation 502 81 11 TABLE B-4 Annual Natural-Gas Consumption for Heating Seasonal Heat Los s, Furnace Natural-Gas Consumption C_ 10 Btu/yr Ef ficiency ~7 P 119 0.60 198 1,980 A 94 0.56 168 1,680 B 81 0. 53 153 1, 530 TABLE B-5 Annual Electricity Consumption for Cooling Hew Gain, Electric Consump- Case 10 Btu/yr tion, kWh P -16 2,400 A 13 2, 000 B 11 1, 700
521 Chemically in Figure B-1. The 888umption8 and nomenclature us" are as follows: · Equal inf titration and exf iltration rates (Vi ~ . · Uniform contaminant concentration (C) in the occupied volume . · Constant outdoor contaminant concentration (CO). · An electronic air-cleaner with an RSP-remova1 efficiency.of c, operating continuously with a constant-supply airflow rate (~ ~ . · A net contaminant generation rate {N)-~decay rates are neglected. A mass balance equation that describes the sir quality of the house is given as follows: · · ~ Vi (CO - C) + Vs (Cs - C) + N 2 V6C and CS ~ (1 - c)C. This set of equations can be combined and rearranged to give the following differential equation for the indoor concentration (C): VdC + (Vi + £V5 ~ C ~ N + at rate of dilution change and in air removal quality ef feats The solution of this equation in: V:CO generation and inf titration effects (1) (2) C = Aft _ ( i 0 )] exp ~( V ) 41 + (I) ' (3) where C i is the initial condition for the concentratio.n . This equation is valid only for constant values of N. vi ~ hi, c, and CO. For this analysis, the generation rate is assumed to vary by steps. Therefore, Equation 3 can be applied to each step separately, with the initial condition for a given step being the final concentration of the previous step. A slightly different model is used for radon, because of the assumption of different concentrations above and below grade. The Mel is shown schematically in Figure B-2 and includes an air exchange (dab} between the above- and below-grade spaces and no generation in
522 f ~ air cleaner, ~ C 8 S V8, C C, V ~1 1 ~ V1, Co FIGURE B-1 General air~quality model for hypothetical single-family residence.
523 above grade ca ~ ma Gibe CO I I_ Gabs Ca ] L Via, CO Cb' Vb ~ N 1 Vab. Cat FIGURE B-2 Radon model. Vib, Ca 1 Via Cb $
524 the above-grade space . All concentrations, air-exchange rates, and the generation rate are assumed to be constant, to give the following aces balances: · · ~ below: Vib{Cb - CO) + Vab (Cb ~ Cal A' and above: Via (Ca - CO) ~ tab (Ca ~ 4) O. These equations can be solved ~ ieoltaneoualy for the above- and below~grade radon concentrations (Ca' Cb): C, = (V V V V V V ) N + CO , (5a) b (ViaVjb ~ Vj,Vab ~ VjbV,b) ° (5b) Generation Rates. The contaminants are generated front several sources, including cooking {carbon monoxide, nitrogen dioxide, and formaldehyde), Smoking (carbon monoxide, nitrogen dioxide, f ormaldehyde , and RSP I, mater ial outgassing ~ formaldehyde and radon), and indoor dust generation (RSP). The assumed daily generation prof iles of these sources are shown in Figure B-3. The generation rate for cooking is assumed to be constant and occurs at 7 a.~., 12 noon, and 5 p.m. for 15, 30, and 60 min. respectively. Smoking occurs at 7 s.m. and 7:30 a.m. and every half-hour from 5:30 pa.. to lie 30 pa.., inclusive. The duration of each occurrence of smoking is 10 min. ~ Material outgassing is assumed to be constant throughout the day. Indoor dust is generated from 7 a.m. to 11 pa.., prisurily acing to resuspension of particles from carpeting. The generation rates for all these sources are listed in Table B-6, with the outdoor concentrations . Concentration Profiles. To determine the daily indoor~ont~inant - concentration profiles' a daily generation prof ile for each contaminant (carbon monoxide, nitrogen dioxide, formaldehyde, and ESPY was determined by supine the generation rates of the appropriate sources. This provides an overall generation profile consisting of step changes to which Equation 3 can be applied, as discuss previously. The solution is started by choosing an initial condition (usually Ci ~ CO) at the beginning of a period (usually 7 ape.) and applying 13qustion 3 to each interval of constant generation rate. The solution proceeds throughout the day and is repeated until no changes occur in the initial conditions from one day to the next. The concentration profiles for carbon Monoxide, nitrogen dioxide, and formaldehyde are shown in Figures B-4 through B-6 for cases 8, A, and B (0.8, O.S, and 0.3 ach). Figure B-7 shows the Patina concentration profiles for RAP for each of the infiltration rates and
525 sutcria1 a:tgass~g-. indoor dust Ga~erat ion Rates N - coo~tclug |~3k$~g ~ woke, l 0 6 12 18 24 Time, has FIGURE B-3 Generation profiles of indoor pollutants for hypothetical single-family residence.
S26 TABLE B-6 A88~P~ Contamtnant Source S~mrA-y Outdoor Indoor Totd1 ConcentratiQn Generation Productlon, Contaminant (CO),a ug/m~ Indoor Source Rate (~), ug/h ~e/d Carbon 1,500 Cigarettesb 31,000 70 monoxide CookingC 1~000~000 1~750 Nitrogen 50 Clgarettesb 474 1 dioxide CookingC 57,000 100 Formaltehyde 5 -Cigarettesb ~ 684 2 CookingC 10~000 18 Materi~ sd 11~000 264 Respirable 2oe Cigarettesb 192,000 450 particles Indoor activitye 8,600 140 Radone O Above grade O O Below grade 256,000f 6,140g aSee Hollowell et al.4 bsee Woods.l2 CCalcula ted from data in Hollowell et al.;6 oven at 350 °F (177.C). dCalculated from data in Hollowe11 et al. eAssumed values fpCi/h. gnCi/d. .
S27 ~JJ 77 ,,, ,,, ~ o Id, . . o ew ~ to . 64 ~ 0 o v v c o K 8 e c' c
528 I/ 0~ 11 it: in r ~ . 8 o I no - - ~ , _ ~ - . . ~ o _ ·D Ed o v C o C) K ~0 ~0 o by l g C'
529 o / <...1 7 1 , ~ 1 ~ 1 ~ I . . , 1 l 1 / < ~ I of 1 l .1 "oh o o Cot o _ _ Al AD 64 . o Cat ll ll o 1 ~ _ 1 .. ll lo 1 Or l _ l Cal ~ ll ~ . Cat 0 0 o v at o v :^ o 1 kit 5 C,
S30 it' o ~ _ ~ , ~1 ~ A l _ 11 ! . Mu ,, , ~~t ,, ~ , , - ~ , 1 ' 4,, 1 ~ , -_ 1 ~ 1 I, I, o ~Z .i ~ l If 1, ! ;! I-/ 1/i 8 ° 8 ~ .: 6a o , _ 0 C _ 0 0 0 o 8 c,
- S31 Q - - . ~ - L ~ C 12 - ~ - ~ _ _ An_ / V - l TIC 1 1 l O 1 ~1 I! _ r ~11 ~1 ~ 8 8 8 8 8 ° ~- 6~ ~ 0 a, 0 - o 0 c o o o a: o so o 0 ~3 - 1 0 V a: ~ 3 ~1 C,
532 a fourth profile for the effect of the electronic air cleaner ( e O. 93, Vs ~ 1,000 cfm) .* The infiltration rate has a negligible effect on the concentration profile after inclusion of the air-cleaner; therefore, only one profile for all infiltration rates is s hown . The cessation of cigarette-amoking has no significant effect on the carbon monoxide, nitrogen dioxide, or formaldehyde concentration profiles. However, it does have a significant effect on RSP concentrations, as shown in Figure B-8 for an infiltration rate of Oe3 ach. Radon, an inert gas, is generated from the decay of radium in the below-grade building materials {i.e., concrete).' The hazardous radiation effects of radon are due primarily to its progeny {R~A, RaB, and RaC). The combined radiation effect of these progeny is taken into account with the working level (WL) defined as:' AL ~ 0.00103 RaA + 0.00507 RaB + 0.00373 RaC, where RaA, RaB, and RaC are concentration in picocuries per liter. The decay rate of radon is 0.0075/h, which is negligible, compared with the assumed infiltration rates of 0.8, 0.5, and 0.3 ach. Therefore, infiltration was assumed to be the only method of radon removal in the model. To calculate the radon concentration profiles, radiation of 0.5 and 1.0 pCi/L we" assumed for the above- and below-grade spaces at the present condition (P). When these values are substituted for Cal and Cb in Equations 5 and it is assumed that the outdoor radon concentration is negligible, compared with,the indoor concentration (CO ~ 0), values of vab ~ 8,960 ft3/h and N ~ 256,000 pCi/h are obtained. The values for the air-exchange rate between the above- and below-grade spaces and the radon generation rate are assumed to remain unchanged for cases A and B. If these values are substituted in Equations 5 with the appropriate infiltration rates, the abo~re~grad e radon concentrations can be calculated for cares A and B; they are listed in Table B-7. Then, from the radon concentration, the corresponding working levels were calculated from WL ~ 1~/100, where Rn is the radon concentration in picocuries per liter and ~ is the Equilibria factor, which is ~ function of the progeny concentrations., Per test cases £, A, and B. a value of ~ ~ 0.84 was used to take into account plateout of the progeny to the walls, and F - 0.32 was used to take into account progeny remover with the electronic air-cleaner. These values for F are approximate comparisons with experimental data from Jonassen. ~ The resulting working levels are shown in Table B-7. A major assumption is made in the remainder of this section: the predicted values are treated as zeal pollutant concentrations. The reader is reminded that the models used to estimate pollutant concentrations have not been validated against measured concentrations. All subsequent comparisons, therefore, are constrained by this lack of model validation. Air~quality health standards for each of We contaminants considered in thin section are listed in Table B-8. These minimal *From manufacturer's data for a Lennox BAC 7-20 electronic air-cleaner.
533 TABLE B~7 Radon Concentrations and Working Levels . Above Grade Below Grade _ Radon Radon Eq uilibrium Concentra- Concentra- Case Factor (F) tion, pCi/L WL tion' pCifI~ WL P 0.84 0.50 0.004 1.00 0.008 A 0.84 0.88 0.007 1.43 0.012 B 0.84 1.58 0.013 2.17 0.018 A filtered . 0.32 0.88 0.003 1.43 0.005 B f iltered 0. 32 ~ .58 0.005 2. 17 0.007 TABLE B-8 At r~Quali ty S tandardsa Coneaminant Concentration Time Stantard Carbon monoxide 40 118/m3 1 h NN~QS Nitrogen tioxide 100 ug/m3 1 yr NMQS Total suspended particles 75 l~8/m3 14yrh NN - QQS Forn~aldehvde 120 ug/m3 Continuous West Ger~an Radon 0.01 WL Continuous 37 FR 25918 aDeri~red from ANSI and ASHRAE.1
534 acceptable values are also plotted in Figures 8-5, B-6, and B-7 for nitrogen dioxide, formaldehyde, and REP, respectively, for comparison with the predicted indoor contaminant concentrations. The carbon monoxide health standard greatly exceeds the predicted values in Figure B-4 and thus are not shown there. Figure B-S shows that the long-term standard (1 ye) for nitrogen dioxide concentration would be exceeded for approximately ~ hid for the present condition (P), whereas cases A and B would exceed the standard for 2 and ~ in/d, respectively. The formaldehyde concentration in Figure B-6 would reach 411 of the short-term standard {continuous) for the present condition {P), 588 for case A, and 86% for case B. Figure B-7 shows that the RSP concentrations would exceed the short-term standard (24 hi for case A during 3.5 hid and case B during 6 in/d, whereas the present condition never exceeds this standard. The lonq-term standard (1 yr) would be exceeded by cases P and A for 11 and 17 in/d, respectively, and cane B would constantly exceed the short-term standard. The inclusion of the electronic air-cleaner would reduce the RSP concentration to a point below the long-term standard for all cases. The cessation of cigarette-smoking without the air-cleaner would also reduce RSP concentrations below this standard for cases P and A. However, case B would exceed ache standard slightly for 13 h, owing to indoor dust generation, as shown in Figure B-8 . Table B-7 shows that the abort-term standard (continuous) of 0.01 WL for radon would be exceeded below grade for care A and above and below grade for cane B. unless the electronic air~cleaner were used. Economics To perform the economic analyst`;, estimates for the installation costs and energy-cost savings were needed for each of the conservation measures considered. ' ' I' Present annual energy costs for natural gas and electricity were calculated by multiplying the annual energy requirements (Tables B-3 and B-4) by the present fuel costs in Ames, Iowa (0.28 $/caf for natural gas and 0.057 S/kWh for electricity) for each of the three cases (P. A, and B). Energy~cost savings for each of the insulation alternatives (A and B) over the present condition {P) were then calculated. The results are listed in Table B-9. The assumed method of insulating for each of the alternatives was to add sufficient cellulose insulation to the walls and ceiling to obtain the desired R value. Installation and material cost e~tinutes from ~ local insulation contractor in Antes, Iowa, were 0.20 S/ft2 Of ceiling area to upgrade from Rll to Rl9 (case A), 0.31 S/ft2 °f2 ceiling area to upgrade from Rll to R30 (case B), and 0.50 S/ft of gross exterior wall area to upgrade from R] to Rll (cases A and B). With an insulated ceiling area of 1,400 It and a gross exterior wall area of 1,576 ftZ, total installed insulation costs of S1.218 and 31.378 were obtained for cases A and B. respectively. These cost" include S150 for caulking and weatherstripping. The only other first cost needed in the economic analysis was S726 for the installed cost of the electronic air-cleaner.
535 Salvage values at the end of the economic life for the various alternatives were also needed. The economic life used was the length of time that the present owner would continue to own the house. At the end of this life (assumed deco be 7 ye}, it was sssumed that the salvage value of the insulation in terms of today's dollars would be the same as its first cost, owing to the increase in resale value of the house. The salvage value of the electronic sir~cleaner was assumed to be 6250. Rates for electricity and natural gas were assumed to increase by 18 and 22%/y:, respectively, and the Farce of general inflation was assumed to be I0%/yr. The economic analysis was performed for three distinct situations, each containing two mutually exclusive alternatives, as shown in Table B10. The inflation-adjusted rates of return, shown in Table 8-10, were calculated for each alterne~i~re over present condition, as well as the inflatzon-adjusted rate of return on the incremental costs for each pair of alternatives. If the homeowner's marginally acceptable rate of return {HARR) were 10%, he should choose alternative B for situation I, alternative A for situation II, and alternative B for situation III. SUMMARY Care must be exercised when considering estimates based on models that have not been validated against measurements. In such cases, the magnitude of the estimated values may not be equivalent to that of ache observed values. Model estimates can be used, however, for comparative studies to illustrate cause-effect relationships among various parameters. From this perspective, the scenarios described in this appendix show that energy-conservation measures may adversely affect the indoor air quality of single-family residences. The inclusion of the cost of sir~quality control may reduce the economic attractiveness of some energy-conservation measures. Although these simulations have been based on several assumptions. they demonstrate the inter- relationships between energy conservation and indoor air quality. In addition, the simulations of this hypothetical residence focus attention on the factors that must be considered in the regulation of indoor environments. R}3CO~=ATIOttS Some parts of the models presented here have not ban validated in practical cases that show their utility. Further research is needed to develop models and to test and validate their usefulness in assessing the relationships between air quality and energy conservation in residential and commercial buildings. A large program should be established to develop this research tool further and to demonstrate the usefulness of models in evaluating indoor
536 TABLE B-9 Present Annual Energy Costs C08t, $ Case Natural Gas Electricity Total p 550 140 690 A 470 110 580 B 430 100 S30 P - A 80 30 110 P - B 12 0 40 160 e TABLE B-10 Inflation-Ad Justed Rates of Return for Hypothetical Examples ROR over ROR on Incremental P coed, % Investment over A' % Situation Alternative 1 A-1 18.3 B-1 23.0 55.1 II A-1 18.3 B-2 13.8 6.2 III A-2 9.5 -- B-2 13.8 55.1
537 environmental conditions. Models may be used in the design of future structures to ensure the health and comfort of the public and conservation of natural resources. REFERENCES 1. American National Standards Institute, and American Society of Heating, Refrigerating and Air - Conditioning Engineers. ANSI/ASHRAE Standard 62-1981. Ventilation for Acceptable Indoor Air Quality. New York: American Society of Beating, Refrigerating and Air Conditioning Engineers, Inc., 1980. 48 pp. American Society of Beating, Refrigerating, and Air Conditioning Engineers. ASERAE Handbook and Product Directory. 1977 Fundamentals, Chapter 22. New York: American Society of Beating, Refrigerating, and Air Conditioning Engineers, Inc., 1977. 3. Engineering Research Institute. Manual of Procedures for Authorized Claus A Energy Auditors in Iowa. Ames, Iowa: Iowa State University Press, 1979. 4. Mollowell, C. D., J. V. Berk, M. L. 8Oegel, R. R. Mike, W. W. Nazaroff, and G. W. Traynor. Indoor air quality In residential buildings. In F. E. de Oliveira, J. E. Woods, and A. Faist, Eds. Building Energy Management--Conventiona1 and Solar Approaches. Proceedings of the International Congress, May 12-16, 1980, Povoa de Varsim, Portugal. New York: Pergamon Press, 1980. 5 . Bollowell, C . D., J. V. Berk , C . Lin, and ~ . Turiel. Indoor Air Quality in Energy Ef f icient Buildings . Lawrence Berkeley Laboratory Report LBL-8892. Berkeley, Cal.: Lawrence Berkeley Laboratory, 1979 . 6. Hollowell, C. D., J. it. Berk, and G. W. Traynor. Impact of reduced infiltration and ventilation on indoor air quality. ASERAE J. 2 1 (7 ): 49-53, 1979 . 7. Jonassen, N. Indoor radon concentrations and building materials control of airborne radioactivity. In F. E. de 01iveirs, J. E. Woods, and A. Faist, Eds. Building Energy Management-~C;onventional and Solar Approaches. Proceedings of the International Congress, May 12-16, 1980, Povoa de Varzim, Portugal. New York: Pergamon Press, 1980. 8. Montag, G. M. A commercial building ownership energy cost anaysis model . In F. E. de Oli~reira, J . E. Woods, and A. Faist, Eds . Building Energy Managen~ent-~Conventional and Solar Approaches. Proceedings of the International Congress, May 12-16, 1980, Povoa de Varzim, Portugal. New York: Pergam~n Press, 1980 . 9 . Repace , J . L., and A . lI . I`owrey . Indoor air pollution , tobacco smoke, and public health. Science 208: 464-471, 1980 10 . Smith . G . W. Engineering Economy . 3rd ed . Ames, Iowa : The Iowa State University Press, 1979. 11. U.S. Department of Commerce, National Climatic Center. Local Climatological Data. Asheville, North Carolina. 12. Woods, J. E:., ventilation, health and energy consumption: A status report. ASHRAE J. 21~7~:23-27, 1979.
