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Development of a Tool forAnalyzing the Sustainability ofResidential Buildings in OhioAbhilash Vijayan and Ashok KumarDept. of Civil Engineering, The University of Toledo, 2801 W. Bancroft St., Toledo, OH 43606; [email protected](for correspondence)
Published online 8 September 2005 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ep.10095
INTRODUCTIONThe building industry is one of the biggest consum-
ers in terms of natural resources and one of the biggestproducers of pollution thereafter, which has alwaysbeen a cause for concern. Various constituents of thebuilding industry together use one third of all the en-ergy and two thirds of all electricity consumed in theUnited States (U.S.). According to the U.S. Green Build-ing Council (USGBC), buildings in the U.S. account for36% of total energy use and 65% of electricity con-sumption; 30% of raw materials use; 30% of wasteoutput, which is 136 million tons annually; and 12% ofpotable water consumption [1]. Furthermore, buildingsare a major source of the pollution that causes urban airquality problems, and the pollutants that contribute toclimate change. Buildings account for 49% of sulfurdioxide emissions, 25% of nitrous oxide emissions, and10% of the particulate emissions, all of which damageurban air quality. Buildings also produce 35% of thenation’s carbon dioxide emissions, the main greenhouse gas [2]. Unhealthy indoor air is found in 30% ofthe new and renovated buildings worldwide. Typicalbuildings consume more of our resources than neces-sary, negatively impact the environment, and generatea large amount of waste. The growing population andtechnological advancements have added additionalburdens on the resources and a point has come whenthe available resources need to be preserved and con-served for future generations. With the growing de-mand and construction, it becomes imperative to havemethods to analyze both the performance and the in-fluence of buildings and to provide accurate assess-ments to improve the living quality.
This has led to changes in the way the design,construction, and operation of structures are ap-proached by the building industry and owners and,subsequently, the move toward environmental perfor-mance and the birth of Sustainable or Green Buildings.Sustainable Buildings incorporate the concepts andprinciples of energy efficiency, water conservation, re-cycled-content materials, waste reduction, buildinglongevity, healthy structures, and the integration ofenvironmental concerns and green construction,thereby striking a balance between social, economic,and environmental performance.
A number of tools are available to tie in the princi-ples of sustainability for both new and existing build-ings [3], although the high costs associated with thesetools make them less usable by the public (see thecomparison in Table 1). Although the available toolsanalyze the individual areas of the building and giverecommendations, none of these tools can analyze theoverall sustainability of the buildings and provide acomparative evaluation of the benefits of using sustain-able options. None of the existing tools gives credit tothe health, living conditions, and sustainable attitude ofthe occupants.
The purpose of this paper is to present the devel-opment of a simple user-friendly occupant comfort andbuilding assessment tool that helps to analyze andassess a building from the twin perspectives of sustain-ability and comfort. This tool aims at creating aware-ness on the advantages of sustainable construction andor remodeling, and educating people about environ-mental issues, possible solutions, and opportunities forreducing environmental impacts, and help people rec-ognize the opportunity to lead an energy-efficient, pol-lution free, sustainable life.© 2005 American Institute of Chemical Engineers
SOFTWARE REVIEWS
238 October 2005 Environmental Progress (Vol.24, No.3)
DEVELOPMENT OF THE TOOLThe steps involved in the development of the tool
and analysis for the assessment of a building include:1. Sustainable Building Concept: Proper study and
thorough knowledge on the principles of sustain-able or green buildings with insight into commonproblems arising from unhealthy, unsustainableconditions.
2. Significant Elements/Factors: Identifying the mostimportant factors that need to be considered forevaluating a building and obtaining the relevantinformation and data.
3. Qualitative Questionnaire: Building a comprehen-sive list of questions and a corresponding scoringmethod for the qualitative analysis of a buildingfrom the dual perspectives of sustainability andcomfort.
4. Tool Development: Development of tool using dataavailable to output results in the terms of cost sav-ings, resource savings, and pollution prevention intables, reports, graphs, and Sustainable Building(SB) Score.
5. Tool Application: Application of the tool to residen-tial buildings for validation and analysis purposes todemonstrate the proper functioning of the tool.
6. Result Interpretation: Identifying and establishingthe basis for interpretation of the results from thetool.Microsoft Excel was chosen as the platform for the
development of the tool mainly because of its easyaccessibility, extensive computational features, andits user friendliness. The tool was designed to incor-porate both quantitative and qualitative approachesof building analysis. The quantitative part of the toolanalyzes a building with respect to the energy andresources consumed and the annual cost incurred.Every unit in the household consuming energy orwater was compared with recommendations and cri-teria for efficient fixtures, which are given by Depart-
ment of Energy Federal Energy Management Pro-gram (DOE FEMP) [4] and Energy Star [5]. The toolalso compares the annual cost incurred by applyingthe user-selected options and compares the potentialannual savings by using the recommended and bestavailable options in the market. The qualitative partcontains questionnaires, the answers to which por-tray the comfort, living conditions, and attitude of theoccupants. Figure 1 shows approaches used in thetool and the different elements under the quantita-tive approach. Details on the tool development andanalysis are given by Vijayan [6].
QUANTITATIVE ANALYSIS
Energy
This tool analyzes the household energy consump-tion that results from lights and appliances such aswashers, refrigerators, and dishwashers and provides acomparison of potential energy and dollar savings byadopting better, sustainable options.
Illumination is a major application of electricalenergy used in an average household. The mostcommon means of illumination used in the Americansubcontinent is by the use of incandescent bulbs.These bulbs are highly energy inefficient, have ashort lifespan, and require frequent replacement.The most sustainable option is to replace these bulbswith more efficient compact fluorescent lights(CFLs). The criteria for selecting a CFL were based onDOE FEMP [4] recommendations for efficient lighting(Table 2) based on the necessary light output. Oncethe type of the bulb used, the number of fittings, andthe wattage of each bulb are selected, the worksheetpulls out information about the necessary lumensrequired to replace the chosen type of bulb andcomputes the total energy consumption of the user’sunits and the sustainable options (Figure 2). This
Table 1. Sustainable Building (SB) vs. other sustainability tools.
Parameter LEED BASIX ENVEST SB tool
Indoor environment quality � � �Energy efficiency � � �Water conservation � � �Appliances � � �Insulation � �Fenestration � � � �Occupant health �Occupant comfort �Occupant behavior �Site selection � � �Alternative forms of energy � � QualitativeHVAC � � � QualitativeBuilding materials � � QualitativeRadon �User controlled � � �User-friendliness N.A. � � �Visual interpretation of results � � �Cost � � � Free
Environmental Progress (Vol.24, No.3) October 2005 239
worksheet also computes the potential savings andthe self-payback period of the sustainable options.
Water
Water usage is directed by the appliances andfixtures used in the house. This includes fixtures inbathroom, such as faucets, showerheads, urinals,and toilets, and other water-consuming appliancesused in the house, such as clothes washers anddishwashers. Most of the time, the water flow fromany water-consuming fixture is more than what isrequired. Selecting the appropriate fixture for the jobcan help regulate the needed flow. DOE FEMP [4] hasset recommendations and criteria for energy- andwater-efficient fixtures and an example is shown inTable 3.
In the User Selected column (Figure 3), the flow rateof the fixture in gallons per minute/flush and the wateruse characteristics of the family including the numberof people in the family, usage per day, and duration ofuse are entered by the user. The total usage days isassumed to be 365, but can be altered by the userdepending on usage pattern.
Water-heating cost for all the faucets and showersis also calculated based on the type of heating. As-suming a water-heating requirement for 6 months,the annual energy used to heat the water is calcu-lated for both the user’s fixture and the sustainableoptions. If the cost of the unit for the DOE-recom-mended faucet is higher, then the worksheet calcu-lates the annual potential saving and the amount of
Table 2. Efficiency recommendation for lights.
To replaceincandescent bulbrated at
Necessary lightoutput (lumens)
Typical CFLreplacement wattage
Recommended CFL lumensper watt (lpW)
Bare bulbs 60 watts 900 or more 15–19 watts 60 lpW or more
Figure 1. Methodology.
Figure 2. Screenshot of the Lighting worksheet.
240 October 2005 Environmental Progress (Vol.24, No.3)
time required to pay back the additional cost of theunit.
AppliancesAppliances are major consumers of energy and wa-
ter, accounting for almost 20% of a typical household’senergy usage. Better selection and thoughtful opera-tion of these equipments can lead to greater comfortwith minimizing cost. Appropriate selection is a majorstep toward achieving increased efficiency.
Appliances considered for analysis were clotheswasher and dryers, dishwashers, and refrigerators.The user is required to select the type of the unit,depending on whether it is Energy Star certified. Ifthe unit is certified, then the user can select the unitfrom the drop-down list given. All the associatedspecifications of the unit are pulled out from thedatabase. If the unit is not certified, then the user isrequired to input the kWh rating and frequency ofusage. For clothes washers (Figure 4), the user is alsorequired to input the washer volume and water fac-tor to compute the water consumption. Based onthese data, the model computes the annual resource(energy and water) consumptions for every appli-ance. The model also computes the heating cost for“warm wash/cold spin ” cycle for the clothes washer.
DOE FEMP has laid out minimum recommendationsfor energy and water use. These recommendations arebased on volume for washers and refrigerators, andenergy factor and electricity rating for dishwashers. Theentire list of Energy Star approved appliances was ob-
tained from their website, and sorted to find the unitthat had the least energy rating and resource consump-tion in every category. The annual savings in the threecategories (water, electricity, and gas) over the user’smodel for the recommended and best models are cal-culated.
Building EnvelopeThe building energy envelope was analyzed for ad-
equacy of insulation and quality of window materialthat is responsible for the most energy leakage in ahousehold. Insulation also acts as a sound absorber orbarrier, keeping noise levels down.
Insulation plays a very important role in restrictingthe energy flow to the outside of the building. Insu-lation is rated in terms of thermal resistance, calledthe R-value, which indicates the resistance to heatflow. The higher the R-value, the greater the insulat-ing effectiveness. The R-value of thermal insulationdepends on the type of material, its thickness, anddensity. The user is required to identify the locationfrom the drop-down menu and indicate the thicknessof the insulating material used. The worksheet pullsout information regarding the R-value of the selectedmaterial. The total available R-value is calculated andis compared with the total recommended R-value forthe corresponding point of application. The ratio ofthe available insulation to recommended insulationis computed to analyze the percentage increase ofinsulation required to make the house energy effi-cient. The user can identify the locations where the
Figure 3. Screenshot of the Faucet worksheet.
Table 3. Efficiency recommendation for faucets.
Product type Recommended flow rate Best available flow rate
Faucet 2.0 gallons per minute or less 1.5 gallons per minute0.25 gallons per cycle (self-closing)
Environmental Progress (Vol.24, No.3) October 2005 241
insulation is below par from the results and can takemeasures to improve them.
Selection of windows plays a very important rolein reducing energy loss, thereby providing a coveredbuilding envelope. Energy consumption of a housecan be substantially reduced if the heat lossesthrough windows can be reduced. This worksheetgives an overview of how the windows in a residen-tial building are performing (Figure 5). The user hasto select the region in which the house is located.The state of Ohio is divided into Northern (mostlyheating) and Central (heating and cooling) regions.The user is required to select from the worksheet thecharacteristics of the window installed in the houseincluding glass type and thickness, glazing type, andcoatings. The tool automatically pulls out the infor-mation on the U-factor, solar heat gain coefficient(SHGC), and visible transmittance (VT) of the se-
lected window glass and glazing. This value is com-pared with the recommended value given for thecorresponding region in the state of Ohio. The work-sheet examines the adequacy of the U-factor andSHGC values and the user is advised to make amendswith windows. The total score is a function of U-factor, SHGC, and VT of the user’s windows.
Figure 5. Window analysis section of the tool.
Table 4. Emission factors.
PollutantEmission
factor
Carbon dioxide 1.8 lb/kWhSulfur dioxide 10.4 g/kWhNitrogen oxides 3.5 g/kWh
Figure 4. Screenshot of the Washer worksheet.
242 October 2005 Environmental Progress (Vol.24, No.3)
Pollution PreventionPollution is a by-product in the process of energy
creation. For every unit of energy production, a pro-portionate amount of pollutants are added to the envi-ronment. Reducing the consumption of energy resultsin reduction in energy production, thereby reducingthe pollution created. By using sustainable units andmeasures in everyday life, the total consumption ofresources also diminishes. Table 4 gives the amount ofpollutant produced per kWh of electricity generated.The tool uses these emission factors for carbon dioxide,sulfur dioxide, and the oxides of nitrogen obtainedfrom the U.S. Environmental Protection Agency to com-pute the total emission of these pollutants and indicatesthe pollution prevention attained by adopting bettersustainable options.
QUALITATIVE ANALYSISThe qualitative section of the tool was developed
to assess the presence of hazards in the living space,which inhibits the comfort of the occupants. A build-ing’s performance can be evaluated by the perfor-mance of its occupants. The indoor and outdoorenvironment plays a very important role in the pro-ductivity and comfort of the individual living in thebuilding. It is important to identify the hazards withinthe space that we live and understand the risks as-sociated with them.
The qualitative section of the tool was developedto assess the presence of such hazards in the livingspace. The procedure for doing the qualitative anal-ysis is:● Identification of common sources that cause nega-
tive flow of energy● Analyzing the presence of such hazards in the living
area● Evaluating the risk associated with the hazard● Informing the occupants and suggesting measures to
mitigate the problemThe questionnaire contains questions that investi-
gate household living conditions, such as temperature,humidity, dust, and illumination, and identifies com-mon indoor hazards such as chemicals, building-re-lated illnesses (BRI), and mold. The user is required toinput the most appropriate response to the questions.The responses are analyzed and scores are given forthe occupant comfort and building sustainability. The
questionnaire is made up of 95 comprehensive ques-tions that deal with the different aspects of the building.For each response, the user is given one point if theselected response is sustainable, or else is awarded nopoints.
COMPUTATION OF SUSTAINABLE BUILDING SCOREThe total SB score is a function of all the sections
given in Figure 1. The SB score is computed as follows:● Total Insulation score is the ratio of the available
insulation to the total recommended insulation.● Total Window score is calculated by assuming the
recommended features of the window to be 50%sustainable. The window score, then, is the sum ofrecommended and total excess value of SHGC, U-factor, and VT available.
● Total gas, water, and electricity scores are calculatedby assuming the recommended level to be 50%sustainable and any excess over this level is sub-tracted from 50%.
● Total Qualitative part constitutes 40% of the SBscore. This is the percentage qualitative scoreachieved out of the maximum attainable.
● The graphs and charts give a visual interpretation ofthe results and help to identify the most sustainableoptions.Table 5 shows the weightage factor given to each
section, and also shows a sample of the calculationperformed.
CASE STUDYThe tool was used to assess a Health House of the
American Lung Association for the purpose of illus-tration. The design criteria for this building wereobtained from the American Lung Association (ALA)website [7]. The house is certified to provide ahealthy and productive living environment. Theanalysis not only helped in establishing the validityof the tool, it also gave an opportunity to indicate theeffect of occupant behavior and attitude on the sus-tainability of a building.
The analysis showed that by following the designcriteria set for constructing a Health House, thebuilding required a considerably smaller amount ofresources to operate. When the energy consumptionwas compared with the recommended level (Table6), the building used a far lower amount of electricity
Table 5. Computation of SB score.
Sustainable Building Score
Contribution to SBS
User Best options Maximum
Total Insulation Score 100.00% 10.00% 10.00% 10%Total Window Score 87.50% 8.75% 10.00% 10%Total Gas Energy Score 48.72% 4.87% 7.50% 10%Total Water Score 51.93% 7.79% 10.85% 15%Total Electricity Score 67.88% 10.18% 15.16% 15%Total Qualitative Score 97.89% 39.16% 39.16% 40%SB Score 80.75% 92.67%
By changing to ideal living conditions, the SB Score can be increased to 93.51%
Environmental Progress (Vol.24, No.3) October 2005 243
Tab
le6.
Tota
lpote
ntia
lsa
vings
inre
sourc
es.
To
tal
po
ten
tial
savi
ngs
inre
sou
rces
Ele
ctri
city
(kW
h)
Gas
(Th
erm
)W
ater
(Gal
lon
)
Co
nsu
mp
tio
nR
eco
mm
end
edB
est
op
tio
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on
sum
pti
on
Rec
om
men
ded
Bes
to
pti
on
Co
nsu
mp
tio
nR
eco
mm
end
edB
est
op
tio
n
Ove
r1
year
702.
7196
1�
152.
9858
0328
4.09
4942
53.4
4123
20.
6757
9213
.875
792
4561
4.36
�89
6.84
9493
.16
Ove
r10
year
s70
27.1
961
�15
29.8
5803
2840
.949
4253
4.41
232
6.75
792
138.
7579
245
6143
.6�
8968
.494
931.
6Fo
rn
num
ber
ofhouse
s,in
one
year
3513
5.98
�76
49.2
9015
114
204.
7471
2672
.061
633
.789
669
3.78
9622
8071
8�
4484
247
4658
50
To
tal
po
ten
tial
savi
ngs
ind
oll
ars
Ele
ctri
city
Gas
Wat
er
Co
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mp
tio
nR
eco
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end
edB
est
op
tio
nC
on
sum
pti
on
Rec
om
men
ded
Bes
to
pti
on
Co
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mp
tio
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eco
mm
end
edB
est
op
tio
n
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r1
year
$42
.16
�$
9.18
$17
.05
$32
.06
$0.
41$
8.33
$18
2.46
�$
3.59
$37
.97
Ove
r10
year
s$
421.
63�
$91
.79
$170
.46
$32
0.65
$4.
05$
83.2
5$1
,824
.57
�$
35.8
7$
379.
73Fo
rn
num
ber
ofhouse
s,in
one
year
$2,1
08.1
6�
$458
.96
$852
.28
$1,6
03.2
4$2
0.27
$416
.27
$9,1
22.8
7�
$179
.37
$1,8
98.6
350 A
ssum
ing
cost
Ele
ctrici
ty($
/kW
h)
0.06
Gas
($/t
her
m)
0.6
Wat
er($
/100
0gal
lon)
4
244 October 2005 Environmental Progress (Vol.24, No.3)
and water. The total expected expenditure by usingthe recommended level was $123 higher than theuser selection over a year.
The total excess consumption graph (Figure 6) has anegative spike in excess consumption, indicating thatthe building was highly energy efficient. The annualexpenditure graph (Figure 7) showed that, althoughthe building energy consumption was lower than therecommended level, there was still room for loweringthe cost by selecting the best sustainable options in themarket. The building received a 97.89% score in qual-itative analysis and 80.75% in the overall sustainability
scoring (Table 5 and Figure 8). This evaluation clearlyshowed that the sustainability of a building is not onlyaffected by the resource consumption and equipmentused, it is also considerably dependent on the occupantbehavior. This indicates that purchasing the best qual-ity pays off in the long run. The total pollution gener-ated was also considerably lower than the recom-mended model (Figure 9).
CONCLUSION AND FUTURE SCOPEFrom the literature, it is certain that no simple, user-
friendly comprehensive tool exists to determine the
Figure 7. Graph of annual expenditure.
Figure 6. Graph of excess consumption.
Environmental Progress (Vol.24, No.3) October 2005 245
sustainability of a building. An evaluation tool forbuilding analyses, which gives the user an opportunityto assess the living space, was developed. The tool canbe downloaded from http://p2tools.utoledo.edu/.This tool provides an easy and reliable way of estimat-ing the building sustainability. It is possible that onemay assign a different SB score to a building dependingon the importance one gives to a particular element.This can be accounted for by changing the percentagesin the final SB score section.
This tool takes a formidable leap in providing theuser with the opportunity to assess the user’s livingspace and make amends to enjoy a better livingstandard. This tool can further be developed to es-tablish a relation between sustainability and occu-pant productivity and performance. Incorporation ofsustainable forms of energy and comparison of theperformance of building by changing to an alterna-tive energy form is another aspect that can improvethe horizons of this research. With further research,
Figure 9. Graph of pollutant emissions arising from energy consumption (CO2).
Figure 8. Graph of qualitative and overall SBS.
246 October 2005 Environmental Progress (Vol.24, No.3)
the tool can be applied to analyze subdivisions, of-fices, and industrial spaces.
LITERATURE CITED1. U.S. Green Building Council. (2005). http://www.
usgbc.org/DisplayPage.aspx?CategoryID�1,July.
2. U.S. Department of Energy (USDOE), Smart Commu-nities Network. (2005). http://www.sustainable.doe.gov/buildings/gbintro.shtml, July.
3. Vijayan, A., & Kumar, A. (2005). A review of tools to
assess the sustainability in building construction,Environmental Progress, 24, 125–132.
4. USDOE, Federal Energy Management Program. (2005).http://www.eere.energy.gov/femp/technologies/eep_eerecommendations.cfm, July.
5. Energy Star. (2005). http://energystar.gov/, July.6. Vijayan, A. (2004). Analysis of sustainability of a
residential building in Ohio, MS Thesis, Toledo, OH:University of Toledo.
7. American Lung Association, Health House BuilderGuidelines. (2005).http://www.healthhouse.org/build/04HHBuilderGuidelines.pdf, July.
Environmental Progress (Vol.24, No.3) October 2005 247
