MEASURED ENERGY SAVINGS FROM RESIDENTIAL RETROFITS:UPDATED RESULTS FROM THE BECA-B PROJECT*

Charles GoldmanLawrence Berkeley Laboratory

ABSTRACT

This study summarizes measured data on energy savings from conservationretrofits in existing residential buildingse Initial data from the BuildingsEnergy-Use Compilation and Analysis (BECA) residential data base werepresented in the 1982 ACEEE Summer Studye We have updated the compilation andpresent results from approximately 115 data sources (almost double the size ofthe initial study) in four general categories: utility-sponsored conservationprograms, low-income weatherization programs, research studies, and multi­family buildings@ We analyze aggregate and individual household energy con­sumption and retrofit cost data and express results from retrofit projects ina standardized format; in the process, we summarize current retrofit experi­ence and identify major data gaps.

The sample size for each project varies greatly, ranging from individualbuildings to 33,000 homes@ Most retrofit projects included in the data baseattempted to reduce space heating consumption@ Retrofits to the buildingshell, principally insulation of exterior surfaces, window treatments, andinfiltration-reduction measures, are still the most popular retrofits,although more data on various heating system retrofits are now ava11able@ Inmulti-family buildings, the average investment per unit is approximately $695,far lower than the average of $1350 spent in single-family residences@ Aver­age annual resource energy savings range from 27 to 40 GJ in the fourcategories. Savings achieved are typically 20 to 30 percent of pre-retrofitspace heating energy use although large variations are observed both in energysavings (absolute and percent) and in costs per unit of energy saved@ Varia­tion in energy savings as well as current data limitations that hamper effortsto and sources of variation are also discussed.Even the wide range in energy savings, most retrofit projects are stillcost-effectivee Approximately 75-80 percent of the retrofit projects havecosts of conserved energy below their respective space heating fuel or elec­

price& Average real rates of return in the four groups range from 13

* The work described in this report was funded by the Assistant Secretary forConservation and Renewable Energy, Office of Building Energy Research andDevelopment, Buildings Systems Division of the U.S@ Department of Energy underContract NO$ DE-AC03-76SF00098e

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GOLDMAN

MEASURED ENERGY SAVINGS FROM RESIDENTIAL RETROFITS:UPDATED RESULTS FROM THE BECA-B PROJECT

Charles GoldmanLawrence Berkeley Laboratory

INTRODUCTION

A recent Office of Technology Assessment (OTA) report concluded thatUdespite considerable theoretical analysis and thousands of audits, there isstill very little documented information on the results of actual retrofits ondifferent types of buildings@" The OTA report stressed that improved data onthe results of individual retrofits, on the results of retrofit packages, andon actual savings compared to predicted could greatly improve the currentsituation in which building owner concern regarding retrofit outcomerepresents a barrier to investment~

The BECA project addresses the lack of monitored building performance datacollecting, and analyzing measured data that document the energy

and cost-effectiveness of conservation measures and practices@ This studyfocusses on retrofitted residential Updated results from

115 retrofit ects are double the size of the pre-vious

retrofit data base 60,000 households) pro-of retrofit under conditions,

this is not a survey of the fraction ofstock that has been retrofitted in recent years@ In this , we

examine factors that account for variation in energy savings among householdssimilar measures@ We also on those (e~g@

for which there is now detailed coverage $ Finally, wedata gaps and areas for research

an of the effects of conservation in

DATA SOURCES

Data on energy and local weather~ and retrofitand cost were obtained from utilities or government agencies that

sponsor conservation programs, research , and firms thatEach ect was placed in one of four broadconservation programs, low-income weatherization

programs, research studies, retrofits of multi-family apartment buildings) toa more consistent and useful treatment of results$

conservation programs are mostly large-scale effortsretrofit of thousands of homes@ They typically reach single-

, middle-income homeowners who live in structurally sound homes@Recent programs typically include a large set of 'shell' measurese The samplehas a distinct bias~ Thirteen of the 19 conservation programs

[ 1 ]

GOLDMAN

(approximately 68%) were sponsored by utilities located in the PacificNorthwest or California and were directed at electrically-heated homes@

The Department of Energy (DOE) Low-Income Weatherization Assistance Pro­gram, the eSA/NBS Weatherization Demonstration Research Project, and pilotretrofit projects for oil-fired heating systems funded by the Low-IncomeEnergy Assistance Program are included in the low-income weatherizationcategory. The DOE Weatherization Program data are often poor out results areincluded from the Program because it focuses on a housing sector where poten­tial increases in energy efficiency are great@ The eSA/NBS project entailedextensive retrofitting of 142 homes in 12 different locations with close moni­toring of energy consumption and cost data@

Research studies often test innovative retrofit measures or strategies@Sample size tends to be small (fewer than 20 homes) and a comparison (or con­trol) group is usually employed as part of the experimental design@ Mostresearch projects relied on whole-house utility billing data in their analysisof household energy consumption although several studies utilized sub-meteredend-use data@

Actual retrofit activity in multi-family buildings lags far behind thatoccurring in single-family homes due to a variety of institutional and techni­cal factors@ The U@S. multi-unit buildings included in the data base are alllocated in the Northeast or Midwest@ The buildings range in size from 5 to1790 units with 68 percent of the buildings larger than 50 units@ The inhabi­tants are mostly renters and are often low-incomee Fifty percent of thebuildings are from public housing projects~ Three buildings were retrofittedby energy service companies who contract with building owners to manage build­ing energy systems@

METHODOLOGY

We want to calculate the energy savings, defined as the change in averageyearly energy consumption, from conservation measures@ In mostretrofit projects, the only information available is whole-house utility bil­

data@ Household consumption data in research studies, the CSA/NBS weath-erization ect~ and some program evaluations were analyzed using alinear model:

= cf + @ (DDR)j

_____ Ei is the average daily energy consumption over period j,DDR is heating degree days per day over period j(calculated using reference temperature R)@

The regression is done using heating degree-days to either a fixed (base18@ or variable reference temperature@ The term « (energy use/day) is anestimate of the weather-independent usage (i.ee, baseload) and the otherparameter, ~, is the heating slope. These parameters, together with thenormal-year degree days to the best-fit reference temperature, are used tocalculate a weather-normalized annual consumption (NAC)e

GOLDMAN

In most cases it was necessary to make one or more adjustments to reportedconsumption data. Regression analysis was performed if monthly billing andlocal weather data were available. Often, actual consumption data werecorrected for the varying severity of winter in different years by normalizingpre-and-post retrofit energy use to a "typical" heating season. We alsoestimated the space heating portion of total usage for each project by sub­tracting an estimated baseload usage. The non-space heating portion waseither derived from the regression coefficient (<<) or was esti~ated by scalingthe summer months fuel usage to a full year.

Gross rather than net energy savings are used in the economic analysisbecause only 40% of the retrofit projects in this compilation included a con­trol group as part of their experimental design; hence, calculation of netenergy savings relative to a control group could not be implemented uniformly@

Retrofit cost data were 'standardized' based on the direct costs ofcontractor-installed measures to the homeowner@ An equivalent contractor costwas estimated in cases where only materials costs were known (i.eo, the DOELow-income Weatherization Program) ° Costs at the time of retrofit were con­verted to constant dollars (1983$), using the GNP Implicit Price Deflators@

We calculate three economic indicators: simple payback time (SPT), cost ofconserved energy (CCE), and internal rate of return (IRR)@ A real (or con­stant dollar) discount rate of 7 percent is used in the economic analysis$ For

buildings, the present value of projected annual operations andmaintenance costs are included in addition to the initial investment (exceptfor the SPT calculation)@ In calculating IRR, residential energy prices areassumed to escalate at a real rate of 4 percent@The CCE formula

assumes constant (1983$) energy prices@ Conservation investmentsare amortized over the measures' lifetime.

RESULTS

Most residential conservation measures at are aimed atenergy in two end-use areas: space heating and cooling, and domes-tic water @ 1 indicates the relative frequency with which variousretrofit measures were installed in each of three data sub-groups: 28 multi­unit , 418 homes that participated in research studies, and 142 low~

income homes from the weatherization project.

implemented in virtually all of the CSA/NBS low-income homes and infrequently in multi-family (MF) buildings (eogG,

15 of MF installed attic insulation)@ The low implemen~

tation rate could be due, in some cases, to adequate pre-retrofit insulationlevels (e@g@, New York City Housing Authority buildings) or to structuralcharacteristics that preclude installation without exorbitant expense (e.g@,flat roof, either clad-wall or masonry bearing-walls)e Heating system (HS)improvements, improved operations and maintenance (OM) practices, or installa­tion of control (He) were all popular retrofit strategies in multi-

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GOLDMAN

family buildings. Forty-seven percent of the low-income homes required windowglass replacement or repair (WR), reflective of the poor structural conditionfound in much of the low-income housing stock.

Conventional retrofits dominate utility-sponsored and DOE Low-incomeWeatherization programs; particularly "shell" measures, window, and hot waterretrofits. For example, attic insulation was the only measure implemented in6 of 19 utility-sponsored programs and was an option ift every program.Approximately 50 percent of the utility conservation programs financed floorinsulation, storm windows and doors, and caulking and weatherstripping.

Most conventional retrofits are well-represented, yet, except for the'house-doctor' experiments, there are relatively few 'innovative' retrofits inthe data base@ More examples are needed at both extremes of the conservationretrofit spectrum; performance data on "super-retrofits" that approach theidentified conservation potential as well as data on low-cost measures.

Energy Savings

There is substantial variation in annual space heat energy savings amongsingle-family retrofit projects at any given investment level (Fig. 2). Forexample, savings differ by a factor of 4 for an investment of $2400e Medianspace heat savings in nineteen utility-sponsored conservation programs are38@4 gigajoules (GJ) and 30.5 GJ in twenty-seven low-income weatherization

ects@

Conservation programs initiated by Tennessee Valley Authority (TVA) andPuget Sound Power and Light (data points Ele1 and E6@1) achieved high energysavings (74 and 96 GJ) relative to cost ($700 and $1450)6 The TVA pilot pro­gram specifically targeted low-income high-energy consumers; hence significantimprovements in building thermal performance were obtained at low cost@

Average space heating consumption was reduced by more than 20 percent intwenty~seven of forty-five (60%) single-family retrofit projects and twenty­two of (63%) research studies (Figs$ 3 and 4). Approximately

of the retrofit ects achieved average space heating reduc-tions of 30% or more@ Average savings were not strongly correlated with pre­retrofit levels although this trend was most evident in resultsfrom the DOE Low-Income Weatherization program@

Several retrofit strategies employed in multi-family buildings were verysuccessful in reducing energy consumption (Fig. 5)e For example, post­retrofit season consumption declined by 44 percent at Page Homes (data

02.1), a 159-unit public housing complex in Trenton, New Jersey, afterthe installation of a micro-computer-based boiler control system@ High pre­retrofit inside temperatures and the buildings' relative energy-inefficiency(e.g., a pre-retrofit hea~ing factor of 482 kJ/m2-DD compared to the U.S.average of 318-353 kJ/m -DDC for multi-family bUil~ingS with similar charac­teristics) are factors that probably contributed to the substantial energysavings@

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GOLDMAN

Substantial savings were also obtained in eight cooperatively- ownedmulti-family buildings in Chicago (all gas-heat data points). Most of thesavings were attributed to various heating system retrofits (e.g@, de-ratingburners in oversized heating systems, installing temperature-sensing burnercontrols, and balancing radiators and steam lines). In one building (SiteLabel G31@S), annual space heating savings were 12603 GJ per unit, a 53 per­cent reduction from pre-retrofit levels, for an investment of $1200 per apart­ment. Prior to retrofit, t~e building was extremely energy-inefficient, witha heating factor of 586 kJ/m -DDC@ Average space heat energy consumptiondeclined by 14.7 GJ in four New York City Housing Authority (NYCHA) buildingsretrofitted with thermostatic radiator valves (data point 08), another exampleof a successful heating system retrofit.

Lower energy savings per dollar invested (i.e@ average annual savings of12@7 GJ for an investment of $1070 per apartment unit) were achieved in aNYCHA window retrofit project that installed double-glazed thermal-breakaluminum windows in nine apartment complexes@ (overall results are showndata point 09)~ Pre-retrofit space heat levels were already fairly low inthese buildings (65-75 GJ) as a result of NYCHA's on-going energy conservationefforts@ Their relative energy-efficiency compared to other multi-familyretrofit projects in the data base is a factor in the low ratio of energy sav­ings to total cost@

Range o!...Savinss am0!1S_ Households

variations in fuel are observed among households in the samelocation that installed similar conservation measures (Fig~ 6)~ For

the middle 50 of the homes, the spread is typically +70% of themedian@ Weather-adjusted energy consumption declined in almost 95 percent ofthe homes, in 17 of 376 homes~ Results from BrookhavenNational REPOIL ect indicate that savings were more variable(and lower) in four groups of Long Island, New York homes thatretrofitted conventional burners with other (Group 5 - vent damper,

6 ~ stack heat 7 - double setback thermostat, Group 8 -thermostat and boiler compared to homes that installeda retention head burner conditions 1) or usedinstallation 2)@

Our data that energy savings for an identical measure tend to bemore variable in mild climates@ For example, Pacific Gas & Electric analyzed

data for two seasons in 32 single-family homes in Bakers-field, where contractors installed R-19 attic insulation in previouslyuninsulated attics (Site Label G12.1)@ The area has a mild winter climatewith an average of 1215 heating degree-days (base 18@30C)@ Median savingswere 10@8 GJ, while 50 of the homes saved less than 4~2 GJ or morethan 18.8 GJ@ Four households experienced increases in space heating usage inthe season following the, retrofit $ Maximum savings were 6@ 7 timesgreater than median savings~ These results suggest that occupant behavior,

indoor temperature preferences~ are a key determinant to under­standing variation in energy consumption in mild climates@ There was less

in energy savings in an attic insulation program sponsored' by a

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GOLDMAN

Michigan utility located in a more severe climate despite the fact that thesample contained more varied building types (i.e., single-family, row houses,duplexes). In this program, R-19 attic insulation was added to uninsulatedhomes.

Efforts to interpret these results are severely hampered by data limita­tions. For example, inside temperature preferences are not available for anyof the homes and conditioned floor area data were not collectea for some datasets (i.e., G12, G30). The large range in savings indicates the need for moredetailed monitoring of key variables that influence energy consumption.

Economic Analysis

Homes in the nineteen conservation programs sponsored by utilities had amedian simple payback time (SPT) of 5.7 years with a mean of 10.3 years@* Fourprograms had average payback periods greater than 15 years@ The median valuefor homes in 27 low-income projects is 9@2 years with a mean of 11.4 years@Homes in the eSA/NBS Demonstration Project that received only building shellretrofits had a median payback time of 13 years; far longer than the median of604 years for 73 homes that received both shell and mechanical system options@Hence, for these homes, the combination of heating system and shell retrofitswas roughly two times more cost-effective than shell measures alone.

The median and mean cost of conserved energy (CCE) in the nineteenutility-sponsored programs ($2.71,2e56/GJ) are significantly lower than thatobtained in the 27 low-income weatherization projects ($4@33,6.33/GJ). Keydifferences that may account for the varying levels of cost-effectivenessbetween these two groups include:

$ problems of poor workmanship and lack of quality control in the initialyears of the DOE Weatherization Program@

~ systematic variations in the choice of retrofit options for example,caulking and weatherstripping were installed in almost all low-incomehomes; energy savings from these measures are likely to be small and are

related to the of workmanship@

i a fraction of the total investment (i.e. ranging from 0 to 25% of thetotal) in low-income homes was often spent for energy-related structural

(e.g~ broken window glass) which raises the cost of conservedenergy relative to middle-income homes$

• overestimation of equivalent contractor cost for homes that used'free' CETA labor 1n the DOE Low-Income Weatherization Program.

* Every project is weighted equally in the calculation of mean and medianvalues~ Note that within each project sample size varies@

GOLDMAN

All fourteen conservation programs directed at single-family electricspace heat customers save energy at a price lower than $O.0675/kWh, thenational average price for electricity (Fig. 7). Seventy-four percent (14 of19) of the single~family gas-heat projects have a cost of conserved energybelow the gas price of $5@69/GJ.

The average cost of conserved energy for 38 research studies is $4.34/GJwith a median value of $3.62/GJ (Fig@ 8). Nineteen of 25 gas-heat data pointshave a CCE lower than $5.69/GJ, the national average price for gas. The clus­ter of gas ......heat data' points with a cost of conserved energy of only $2/GJ at afirst-cost of $400 represent "house......doctor" treatment results from PrincetonUniversity's Modular Retrofit Experiment@ This complex retrofit was lesscost-effective with CCE's of $4-5/GJ in research projects conducted by theBonneville Power Administration and Lawrence Berkeley Laboratory (Ea@l andG27@1). In these projects, researchers concluded that in mild climates it wasparticularly important to focus "house-doctoring" efforts either on homes withhigh infiltration rates or that could be retrofitted with cost-effective non­infiltration measures (i@e., inexpensive hot water and heating system retro­fits)@

CONCLUSION

Key findings from thisresidential

compilation of currentare shown in Table I@

retrofit experience in

Table 1~ Key Findings~

Multi FamilyResearchLow-IncomeUtility ....Programs Programs Studies Buildings

1", Sample Size N m 19, comprising N ~ 30, comprising N m 38, comprising N m 28 bldgs ..43730 hOlies 938 homes 352 homes

2", Cost of Retrofit (1983$) -Median 705 1370 824 533-Average* 1044 .± 702 1578 ± 863 1685 ±. 2747 695 .±. 551

3" Space Heat Savings (GJ!Vr)** -Median 38,,4 30 .. 5 2708 15~1

....Average 40",3 .:t 21 ~O 31",8 .±. 26~2 34 .. 3 .±. 24 .. 4 27",0 ± 27~4

4" Space Heat SaVings (%) -Median 24% 22% 22% 22%-Average 26 .± 11% 24 .± 12% 25 ± 14% 26 ± 14%

5" Simple Payback Time (Vrs) -Median 5~7 9",2 6.. 4 4",7....Average 10 .. 3 11~4 9.. 5 7.. 9

6 .. Cost of Cons .. Energy (S!GJ) -Median 2 .. 71 4.. 33 3 .. 62 541103D R 7% real -Average 2 .. 56 .i 1.. 29 6,,33 .± 4.. 63 4,,34 .± 4.. 05 5.. 26 ±. 3,.31

7 <- Real Rate of Return (%) -Median 25% 6% 17% 11%-Average 23 ± 15% 13 .±. 14% 31 .±. 35% 27 .± 31%

~.

* Mean .i standard deviation

** Electric space heat savings are measured in resource energy un1ts~ 12 .. 1 MJ/kWh

occurred after retrofit in almost all retrofit projects,of data category. Average annual resource energy savings range

from 27 to 40 GJ in the four categories@ Savings actually achieved are typi-20 to 30 of pre-retrofit space heating energy usee These

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GOLDMAN

results suggest that most efforts to date have fallen well short of estimatesof the identified technical potential. There is little evidence of success­ful, cost-effective retrofits involving expenditures of more than $2500 perhouse. In multi-family buildings, the average investment per unit is approxi­mately $695 with a maximum of $1650, far lower than the average of $1350 spentin single-family res1dencese

Large variations are observed both in energy savings (absolute and per­cent) and in costs per unit of energy saved. For aggregate data, representingresults from groups of retrofitted homes, savings between various groups varyby a factor of five at any particular investment level@ Moreover, there 1ssignificant uncertainty in savings estimates that are based entirely onchanges in total billed energy use before and after a retrofit. Evaluationstudies of conservation programs rarely sub-meter heating energy use or moni­tor inside temperatures; hence possible equipment changes in the house (eeg@appliance replacement or use of secondary heating equipment) or in occupant'sbehavior (eeg. adjustment of day or night-time temperature) may mask theactual effect of the retrofit@ At a minimum, evaluation studies shouldinclude a telephone or on-site survey of occupants in order to obtain data onother factors that cause changes in a household's energy consumption; a tech-

used in only a small fraction of the evaluation studies@ The wide rangeof conservation results indicates that more detailed monitoring are needed inorder to answer questions on the relative savings contribution of individualmeasures in homes that receive several retrofits or interactive effectsbetween occupants and retrofits@

cost-effective retrofit strategies can now be validated basedconsumption data The installation of attic insulation,

in homes with little or no insulation, produced substantialenergy savings and was cost-effective in every retrofit project, irrespectiveof structural and demographic characteristics or climatic region. Conservationmeasures to reduce domestic hot water usage~ typically tank and pipeinsulation reduced-flow , were also sound energy-efficiencyinvestments@ of retrofit measures (typically 1nclud-

attic insulation and storm windows and often wall or floor insulation)were successful in most electric-space heat homes. In 1ow­income homes, retrofitting existing gas or oil-fired heating

appeared to be a very cost- effective complement to "shell" weather­ization measures@ Results from several pilot programs (i.e., Philadelphia 011Furnace Retrofit ect) indicate that the cost-effectiveness of low-incomeweatherization can be enhanced through the development of administratively

programs that utilize well-trained private contractors to install vari-

* These conclusions are drawn from where thedividual measures or sets of measures could be isolated@

of in-

GOLDMAN

The conservation potential in mUlti-family buildings 1s large and barelytapped. A variety of barriers, both institutional and technical, hinder theoptimal allocation of resources for energy-efficiency investments@ Retrofit­ting existing heating systems to increase their efficiency and installation ofmeasures that improve building temperature control are attractive energy­saving strategies in multi-family buildings and can also provide occupantswith a higher comfort and amenity level. However, more data are needed, fromdifferent climatic regions, additional building and/or heating system types,and varying combinations of who pays the heating bill and who controls theheating system energy use to determine if these preliminary results can bewidely replicated.

From a homeowner's perspective, many conservation .measures are attractiveeconomic investments compared to either alternative investment possibilitiesor continuation of consumption levels at current residential fuel or electri­city prices@ Average real rates of return in the four groups range from 13 to31 percent. Approximately 75-80 percent of the retrofit projects have costsof conserved energy below their respective space heating fuel or electricityprice.

gaps orperformance

, this compilation highlightsavailable on the measured

residential buildings:

limitations in the dataof retrofits in existing

• Limited data are available on the effect of residential retrofits onpower and cooling energy requirements. We have had limited success inobtaining data from those regions of the country (i@e., Southeastern andSouthwestern U.S@) where cooling accounts for a substantial fraction oftotal residential energy usee There is also less data on retrofitsdirected at end-uses other than space heating@ Studies of active and pas­sive solar retrofits are not properly represented in the data base, oftenbecause of cost data@

$ Measured data on retrofit in multi-family ,are still retrofit strategies

noted in this ( temperature control within the building~

the of an existing heating system, lighting retro-fits) must be tested in other climatic regions and varying building types@

~ There are insufficient data on energy savings trends over a period ofyears after retrofit@ Information on the persistence of initial savingsfrom conservation measures will allow researchers to improve estimates of

lifetime, though long-term tracking via utility bills onlydifficult problems (i~e. occupancy and operating changes, addi­

tional retrofits). This is an important area because the economic attrac­tiveness of conservation investments is strongly affected the assumedlifetimee

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GOLDMAN

REFERENCES

A complete listing of all the sources used in assembling the retrofit database discussed in this article may be found in the following reference: e.A.Goldman, Technical Performance and Cost-Effectiveness of Conservation Retro­fits in Existing U.~. Residentia.r-B~ings:Analysis of the BECA-! data base,LBL-17088, Lawrence Berkeley Laboratory, October 1983.

8-117

Fi~ure 1..

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100

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AFmOAT CATEGORY Wetm

Relative frequency with which retrofit IIlMUllSUres were installed in each ofthree groups (research studie., multi-fuily buildings, low-income homes par­tic1 pating in the CSA/NBS OelllOnllll:ration Project) & The _asure code key 1s:lA, attic insulation; XU ~ vall 1nsulat10n; U t in3ulat10n of miscellaneousareas or unspecified; CU. CR1\llk1ol and weatherstripping; PI, infiltrationreduction using blowr door pressurization; HS, heating system improvements;HC or T. HVAC controls or clock tMrtIIIlOstats; OM, operations and u1ntenanceactions; WM. v1odov unageRnt; WIt. window repair or replacelRent; W'H t vatertlt~at1Dg retrofits ..

SINGlE...FAMILY FlFmOFrr PROGRAMSF"""-""""""""""""'_........_-.._........_-_1!lI1llllllllll~._---"""""'- .................""""""Ii'1OO

611S7

Figure 2.. A.r1owal space heat energy savings are plotted &Iainst the fir8t-coGlI: of theretrofit for utility-sponsored and low-inco_ watherization prOSE'g86> The 47data points represent rel8ults from over 60,000' ho.e. The 8lop1nS referencelines show the minimum energy salvings that llIUst be achieved ~ for each level ofinveat_nt. if the retrofit is to be cost1ffective capered to national a"er­age residential pr1ce.. for fuel and e18ctric1ty", This m1niDlWlll is calculatedas the present value of the flners)' purcMlIIIes which would be necelulllary if theretrofit were not installed 11 elilulumiq a 15 year liietiM. constant (1983$)national Average energy prices ~ and a 7% real discount rate & Note, however ~

that there Are re,ional variations in the price of gas and electricity ~ sothat coet-effectivene811l of individual retrofit projects uy be different fromthat indicated here.. Electricity 18 DIIeullsured io resource units of 12& 1 HJ perkWh 02.1 MJ llIlII 11 ,500 Itu).

8-118

SINGlE-FAMIlY RETRORT PROJECTS

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20 40 80 80 100 120 140 130 .0 200 220 240Pre-Retro#it SpacoHe8t Energy U.e (GJ)

Figure 3e Annual space heat energy ~avinls as a function of pre-retrofit space heatenergy use 1n 45 single-family retrofit project8e Electricity use 1sexpressed in terms of site energYD 306 HJ per kWh ()413 Btu per kWh)e

REmORT RESEARCH STUDIES

1600

20%

300 800 900 1200Pre""Retrofit Space Heat Use (MJ/m2)

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Annual space heat energy savings in 35 research studies are plotted againstpre-retrofit space heat consumpt1on0 Usage has been normalized by householdfloor areae Electricity use is expressed in terms of site ener~y (3e6 HJ perkWh)e

MU1:n-FAMl,Y AETROATS

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Total colt/unit (11131)......nm.u.

Annual resource energy savings are compared to the total cost of the retrofitinvestment in 26 multi-unit buildings. Savings and costs are divided by thenumber of apartuent units in that building. Hean annual savings are 24.7 GJper apartment unit. In Rost cases, the savings apply to space heat only,except for 5 buildings where the retrofit addressed both space heat and domes­tic hot water usageo In those 5 caaes 9 we plot the combined sav1ngs1P Totalcost includes the initial investment plu8 the present value of annualestimated additional operations and ..intenanee costs over the estimated life­time of each 8ea3Ure~ Reference lines for conservation cost-effectiveness aredefined as in F1ge 2e Electricity 1s measured in resource units of 12el MJper kWh (1201 MJ ~ 11 t SOO Btu).

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llJ.J. III 11.J.lllll~r tf .tll iO 32 1$ 12 13 M 40 18 27 14 I 17 21 14 14

L---.J 1-.1 l-.J l...J 1 I , I

AttIC AtllC :-. IJiftE'= t.=~1 ....=ftan~e in annuBl fuel savi~gs among households installing similar 8e8SUres&The site label, number of homes in the project~ and description of theiostalled measures or type of program are included below each d1str1but1oDoIn most cases, the savings apply to space heat only, except for the heating.ystem retrofits and the "house-doctor lt experi_ate where COD8W11ption includesall end uses of the space heating fuelo weather-adjusted energy coneu8ptionactually increased in 5 perceot of the households (17 of 376 h08es)~

3 (;...2 eo

0U

010004000

TV" of prPS:.. DOE W.atheriZationa CSAINBS• Utitity Programo Cit Fum-Ke Retrofi,t~

o

o

o

o

2000 3000Contractor coat (1983 I)

1000

·0a

O.........-~--"P"""""' ........._.........-F""""'-~-.........,,----llI!llI!IJllIJf--~--4-o

13

SINGlE-FAMilY RETROm PROGRAMS14 P-......O·----••·~-- ..........-O~------------1lIiIIIl8f'" 16

17.35 ".3

The cost of conserved energy (CCE) is plotted agaiost ~he contractor cost ofretrofit M.sure_ for 46 utility-sponsored and lo""';lncoM weatherization pro....gram.o eCE equAls the ratio of annualized investment divided by anDual energysavings t where annualized investment: equals total investHnt multiplied by acapital recovery factor~ The horizontal lines represent national averageprices of purchased energy againBt which conservation retrofits can be com­pared~ Electricity use is expressed in resource terms (12$1 MJ per kWh)e

RFmOm RESEARCH STUDIES

11

•6 !iJ GaiJ. S6.61/GJ 11m sO.eOlT'horlTt

--.,------ ---~-;;tv" S01iiWkWhe

6 ~cl' DOH ...@ e @

e4-

@ @ @lm e @@

~<4

3 @

Jt ~ ~~ ""'led mt.:

2 CIt GI.2

~ Oil!II Ekectrecity

~Mft£

O........--""""""'~!"""""""---"'""""'¥'- ........._-""'f"""'.................._-"l""""""---~Oo 1000 2000 3000 4000 6000

Contractor cost (1983 $)

The cost of conserved energy ao a function of the contractor cost of theretrofit is shown for 38 research stud1e8o The mean CCE is $4 e 34/GJ while theeed1ao value is $3e62/GJ$ Referen~e lines are defined as in F1g0 ge

13-121