EVALUATION OF RESIDENTIAL BUILDING ENERGY PERFORMANCE STANDARDS

David B. Goldstein, Mark De Levine,

Metin Lokmanhekim, and Arthur He Rosenfeld

Lawrence Berkeley Laboratory

INTRODUCTION

Performance Standards

The u.s~ Congress designated energy-performance standards as a means

of reducing energy use in new buildings all These standards differ from

the more conventional "component-based" and prescriptive standards by

setting a limit on predicted energy use of the building as a whole,

rather than by specifying the thermal performance of each element of the

building separatelye3 The performance aspect of the standards allows

builders greater flexibili ty in meeting their requirements, since the

performance of one component can be traded off against the low per­

formance of another@ In spite of this greater flexibility, these are

more difficult to implement than prescriptive standards@

This paper discusses the process of applying life-cycle cost

to the evaluation of performance standards· for residences @

life-cycle costs of a building can be accomplished by simu­

the energy performance of a prototype building on an energy util­

ization model under conditions of thermal integrity. The effect of

conservation measures to the base house is modeled, and for each

measure the reductions in energy costs over the life of the building are

to the increased investment in energy conservation.

Conservation measures are added in order of decreasing benefit/cost

ratio until the ratio is less than one& The energy budget at this

minimum in life-cycle cost is hereafter defined as the "design energy

budgetU of a building type~ Energy performance standards can be set by

requiring all buildings to achieve the same or better (i@e@, lower)

energy performance as the coat-minimizing prototype@ If there is a sub­

stantial difference in the abilities of different types of buildings to

achieve this performance, different prototypes can be established for

each type of building.

The energy budgets derived by this method ar~ abstract numbers (Btu

per square foot per year); additional study is needed to relate these

numbers to specific configurations of specific houses (other than the

prototype)~ Sensitivity of the design energy performance of a building

to different building parameters must be explored before the energy

budget can be assumed to be realistic for a wide variety of houses~

Many of the key issues revolving around standards con-

cern their applicabili ty to different types of houses a.nd the assump­

tions used to model the energy use and economics of the This

report derives energy budgets for residences based on minimizing life-

costs of conventional conservation measures to the consumer (home

It shows that the houses with conservation measures and energy

associated with the minimum in costs are relatively

insensitive to most variations in house design~ Therefore, energy budg-

ets are well defined and table compared to ive standards@

Rule on

issued in November 1

used these budgets and an attendant

Northwest Laboratory, 1 as the basis of the Proposed

Standards (BEPS) for Residences,

@S@ , 1 Commercial

standards ( those for multifamily

~_.~~~~~&.~~_) are based on a statistical methodology developed

the American Institute of Architects Research Corporation (American

Institute of Architects, 1

Summary Of Results

If all new residential buildings incorporate traditional energy­

conservation measures until the minimum in life-cycle cost is achieved,

then:

o A reduction of 30 to 40 percent in the average energy use for

space conditioning (from current building practices) is accom­

plished;

o A reduction of 60 to 70 percent in average energy use for space

conditioning (from an average existing house) is obtained;

o Simple return on conservation investment occurs in 1 to 4 years

for electric heat and 3 to 10 years for gas heat;

o An increased investment of $O~50 to $l~OO per square foot for a

new house is required (i@e$' ·an increase in initial investment

of 1 to 2 percent), and

o The consumer achieves a net saving of $800 to $1500 on the cost

of fuel (and conservation) over the life of the house mortgage@

If the list of available conservation measures is expanded to

include reduced air leakage (inf into the house t coupled with

mechanical ventilation through a heat exchanger (not yet widely avail­

able) and these measures are until the life-cycle cost

minimum is achieved, then:

o A reduction of 50 to 60 percent in average energy use for space

(from current building practices) or 75 to 80 per-

cent (from an average house) is accomplished

o An increased investment of $0$75 and $1@50 per square foot for

a new house is ~ and

o lbe net savings is $1)500 to $4,000 to the consumer$

METHOD OF APPROACH

The approach followed in the of residential space-

conditioning energy-performance standards involves the following steps:

Ie Development of residential prototypes

2~ Selection of conservation measures to be evaluated

30 Description of standard conditions

4e Development of economic data, projections, and assumptions

5 ~ Computer simulation of energy requirements in dif-

ferent climatic

6~ of costs of energy conservation measures

7@ Sensit

conditions)

on characteristics, operating

measures, and economic

of ts of alternative energy

which the alternative t levels are based

7*

levels, in

on steps 1

achieve a minimum in

work for tl>..~"",'l.."'&.I~p;;;;.

labor and

of the

tate the

is the basis of the method $ Trying to

costs is a reasonable basis for estab-

~ since it a rational frame~

off scarce energy resources and other resources (e~g~,

) to reach a (in this case) space con-

in residential ( et al$j 1979)@ Acceptance

cos can, in our , greatly facili-

that is necessary to establish the major

elements of a national energy This does not

mean that a consensus is easy or wi thout its

divisive However ~ the use of an economic approach to energy

conservation--and the increas awareness of how economics can

resolve issues--can be enhanced a government decision to

cos as a element of itsuse

Specifics of Approach and Assumptions

Table 1 summarizes the most important elements of this approache

More detailed information on the assumptions used in the analysis is

found in Goldstein et al@, (1979)3 More detailed information about the

results of sensitivity analyses is found in Chapter 4 and appendices A

and I of Pacific Northwest Laboratory (1979)&

Assumptions (based on the best available data) are required in all

of the areas listed in Table 1 ~ Three of these areas are discussed

under the following headings0

Prototype houses

The economic approach to energy-budget analysis requires the use of

prototype buildings @ Cost/benefit analysis cannot be performed in the

abstract; improvements on specific houses 'm.ust be st'udied 0 The

used are described by Hastings (1977) 0 They cover ranch

houses, two-s houses, and townhouses@ In addition, we modeled a

t-level

The Has houses were used in the analysis because they were

measures and have been subject

to and review for over a year@ We made several modifi-

cations to the basic to determine energy budgets.

Window area was increased from 11 to 15 percent of floor area, to

to data on average areas in new construction@ The win-

dows were distributed on all four eleva.tions to simulate ran-

dom orientation~ These loosened the energy budgets, so that a

house could available conservation

measures alone, without the of reorientation (which may not

be in many cases)~

Table 1Cost

to Evaluating the Life-CycleMeasures for Single-Family

Residential Bui

RESIDENTIAL PROTOYPES

o Four designs selected, following Hastings (1977): single-storyranch, two story, townhouse, and split-level house

o Window area taken to be 15 percent of floor area for all designs

o l~i nifows di at ri buted on all four sides of house (twosides for townhouse)

o Sensitivities of prototypes--window area--window orientation--house size ann orientation--aspect ratio of house--thermal mass of house--conservation measures (see below)--bu!l conditions (see be

CONSERVATION MEASURES

o Windows: up to triwi

ng (or double us storm

o Exterior wal1- up to R~25 (us)

2 u x 6 U studs insulating

o Ceil up to R-38 insulation

o exterior wall wi th double studs (two 2 u x 4 u or 2 tG xg~~ studs wi th insulation); ceiling insulation than R-38;infiltration reduction th or without heat ; anyconservation measure a in behavior; otheradvanced energy~conservation technol

BlJILnING OPERATING CONDITIONS

Thermostat set for heat for cooling;

o air nf11tration rate: 0.6 air per hour

o internal loads: 50 ~ 000 Btu per day, highest in(cooking, s~ 1 ) and (cooking,

'V....,,"-UJ..PQ.!l.;a.~s, tele'vi

temperatureto cool

wi ndows con-

Natural ventilation: windows open whenthan and outdoor

house to 7 in less than one hour ~

sidered as a sensitivi case~

o

(Table 1 cont'd)

ECONOMIC DATA, PROJECTIONS, AND ASSUMPTIONS

o Energy Information Administration average energy-price pro­jections (Series B)

--Gas prices escalate at 2@8 percent per year above infil­trationG

-~Electricity prices escalate at 1~5 percent per yearabove inflation@

o Installed cost of energy-conservation masures from NationalAssociation of Homebuilders

o Discount rate chosen to equal cost of borrowed capital for anew house (3 percent above inflation)

o Possible future changes in assumptions:--marginal energy prices--updated conservation costs--regional prices

BUILDING ENERGY SIMULATIONS

o Use of DOE-2 computer program, checkedBLAST

"""'F-t,liod> ..... A.A...., t TWOZONE and

o in infiltration and ventilation al thms

o Run for 4ures percities

, about 12 groups of conservation meas-prototype, two ventilation 81 thms, and 10

conditions

conditions in the were chosen to reflect current

usage choice was made to limit the scope of the perfor-

mance standard to in , with no effect on the

or of the If one assumes changed

@g~ lower thermostats), then insulation stan-

dards in comfort ( which may float than

the actual thermostat set but lower than the desired ) which

cannot be evaluated

da.ta, though

do open their windows

of closed ~ndows

on natural ventila­

the use of pa.ssive

mandate@

We assumed natural ventilation because the

sparse and inconclusive, that most

on cool summer Furthermore ~ tIle

would cause solar (which often

to have loads,

solar which have received

Infiltration

with coef­

and Coblentz j

of the aver-

Internal load ions were based on average

ance and efficiencies@

rates were calculated a Coblentz~Achenbach

ficients R~ Petersen

1 ) w The average, 0 ~~ 6 air per 110ur ~ is

ages of measurements made in over 50 houses~

ECOl1.0mic data. and

A discount rate 3 above the inflation rate was used, based

on the cost of to the consumer a new homee A

discount rate, such as 10 or 15 above inflation~ reduces

the number of conservatlon measures that are cost-effective, icu-

in milder climates* A lower discount rate increases the number of

cost'='effective measures in moderate and mild climates~

The rate was conais with the cost

since C011serva tion measures wJere evaluated based on cos t to the home

(rather than to the builder) ~ and the fuel are those

to homedwellers~ not to the natiou@ it is con-

sistent to use costs to the consumer as the discount

2 .. 12

rate@

One might want to recalculate cost minima using national parameters,

i.elll.. , marginal fuel prices, increments for environmental degradation,

effects on balance of payments and national security considerations,

manufacturing costs for conservation measures, and a social discount

rate@ Clearly, these parameters are more difficu1t to evaluate than the

consumer-oriented parameters@

Preliminary results suggest that the use of parameters based on

national impacts would result in standards as least as stringent as ones

based on consumer impacts@

Comparison with Approach used to Evaluate Commercial Buildi~gs

The American Institute of Architects Research Corporation (AIA/RC)

performed an analysis (American Institute of Architects, 1979) of com­

mercial buildings that was used by the Department of Energy in much the

same way as our research was used to select the design energy budgetse

The approach taken by AIA!RC differed markedly from that used to analyze

s residential

A recent book published by Resources for the Future (RFF) (1979),

Next Twenty Years, it an excellent summary and cri-

of the taken to commercial buildings:

""""~"""'~&JI."",

and coolingin the ~)

calculations indicated thatwere more

in the ori­attention to

fifth of thethe power of

deal with ite;

The

foot theresearchersbuiltthenaltion(Thethat

the standards bethe energyAmerican Institute of

to collect the dataselected 1,661

bargo, on the some-dubious those build-

in6s would have energy conservationin their design stage 0 a programowned by the Edison Institute, t:he buildings were

to calculate how many British thermal units per squarewould use per year@ the

did not go back to see whether the asas the a small sample of

were Their origi-a course in energy conserva-

to the to save more energy f$

instructions included the limitationthe new was not to cost any more than the original

This instruction eliminated mostto make the morethat capital no for

was freed to be usedeno ) the

four out of five theefficient than all but the

have been in the process~

were not made available) and littleto the question of mo'ney, either in theor in the

written an economist who would

have to see standards set on the basis of life-

costs to ) whether or not that to be

constructed at median energy use or at 8. level below

there are many practical similarities

cos method for residences and

used for the commercial sectOI"@ In

Nevertheless~butl ®

between the results of the

those of the statistical

cost would involve the use

~M;.1""'&Jl,~~PvPJ.~;'~.l!..,.~) or (e ~g @ ,

in residences) which

and builders, but which

both cases, true minimization of

of measures *g@, residential

in, offices or

are not available to

could lead to energy savings larger than those mandated by the energy

budgets DOE chose~ Thus, for both sectors and both methods, the energy

budgets are on a declining portion of the cost curve, where more conser­

vation would lead to lower costs ~ However they both run up against

DOE's current judgment of industry capabilities.

Nonetheless, the points made by RFF are extrt~ely important, and we

anticipate that DOE will note them as they continue the research in sup­

port of the final rule. It is not as easy to perform life-cycle costing

for commercial building prototypes as for residential prototypese How­

ever, such an approach has been initiated at AIA/RC and is likely to

provide results that are extremely useful for the final BEPS rule.

RESULTS OF THE LIFE-CYCLE COST ANALYSIS

Houses Heated with

Ta.ble 2 contains the detailed resul ts obtained by minimizing the

costs of energy-conservation investment and a discounted

stream of payments for fuel over the lifetime of the house mortgage~

The table assumes a house with natural gas heating (with a system effi­

of 70 percent) and electric cooling~

Table 2 - Results of the Life Cycle Cost Analysis of Energy Conservation Measures forSingle-Story Houses Heated by Natural Gas and Cooled by Electricity

Heating and cooling degree days base 65°F presented; heating degreedays base 530 F in parentheses; cooling degree days base 680F inparentheses

Minneapolis

2 Chicago

3 Portland

3 Washington~

DeC"4 Atlanta

4 Fresno

5 Burbankc

6 Phoenix?

6 Houston

7 Fort Worth~

..

Ceiling Wall Floor

8,310 530 38 25 t(5,260) (370)

6fi 130 930 38 19 t(3f/640) (620)it, 790 300 38 19 19

( 1 ~ 840) (150)4,210 1~420 38 19 t

(1,980) (1,010)3,100 1,590 38 19 11

(1,230) (1,130)2,650 1)670 38 19 t

(770) (1,220)1,820 620 19 11 t(170)f (310)f

1,550 3,510 38 19 t(320) (2,960)

1,430 2,890 30 Ii t(360) (2,240)

2,830 2~590 38 25 t(810) (2,030)

'*ClimateRegion

*Representative

City

*Heating

*Cooling

'*Insulation Levels

(R-Value)

'* * *Number of Conservation Energy BudgetGlazings Investment Primary Energy

(1978 Doliars) (MBtu/ft 2/year) (MBtu/ft 2/year)

3 1,160 66~1

3 900 42c;9 35~O

3 I~050 30~9 25",9

3 900 33<1'7 22*4

2 900 28~2 18,,)

2 850 31,,9 16~1

2 380 15,,7 7r;p2

3 1,200 3SCl8 1200

2 520 34 4 15i>1

3 1,280 32~3 1592

t Not applicable

""I---lN"t-&N

f

§

degree days for Los Angeles reported

Under the EIA Medium Price Projections (December 17, 1978) bothPhoenix and Fort Worth would have used double glazing at a conserva­tion investment of $850~ Primary energy use was 40~1 and 36eB MBtuper square foot per year for Phoenix and Ft Worth, respectively&

The first column lists the climatic regions, and the second presents the

representative city for which the thermal analysis of the residence was

performed 0 The third and fourth columns show the long-term average

heating and cooling degree days' for each of these cities @ The heating

degree days are presented with a base of 650F and, in pa.rentheses, a

base of 530F. The cooling degree days are presented with a base of 650F

and in parentheses, a base of 68oF$ (The 530F base for heating and 680F

for cooling are included because space heating and cooling loads for a

well-insulated house are expected to be more nearly linear with degree

days calculated on this basis than for the traditional base of 650F~)

The fifth column presents the insulation levels, and the sixth

column displays the number of glazings in the prototype house that

minimized life-cycle costs~*

(The estimates of current conservation investment

the Nattonal Association of Home Builders whose

energy

are based on a survey

results appear in Table 3) "* The column contains the energy

at the t minimum, which we have previously defined

of a house@ We have expressed these budgets

energy use and use at the bu~lding boundary~y~

in terms of

as the

These insulation levels would bring most houses into compliance with

the energy budgets 0 Of course, many other configurations would also

is used in climates as cold as or colder than

, D@C~, and in areas with a very large cooling loade Double

is used in all other climates modeled~ Typical insulation lev­

els for all but the extreme climates (coldest or mildest) are R-38

( and R-19 )0 The seventh column contains the estimated

increase in investment (for an 1176 square foot house) for the conserva­

tion mea.sures with current investment in conservation in the

different climates@

* Table 2 notes the floer insulation levels for regions in which a crawlspace is the common form of basement0 For unheated full basements, the

is made that heat losses and gains balance. Slab-an-gradeand basement construction is assumed to have adequate perimeter insula­tion, as described in Pacific Northwest Laboratory (1979)~

Table 3 -- Stanard Energy Conservation Measures for Residential Houses Constructed in 19

Standard Practice, 1975

City Ceiling Wall Floor Number of GlazingR-Value Rtli Value R@ Value For all Windows

22 11 (*) 2Chicago 19 11 (*) 2Portland 19 11 7 2Washington, D.C~ 19 11 (*) 2Atlanta 19 11 7 1Fresno 19 11 (*) 1Burbank 19 11 (*) 1Phoenix 19 11 (*) 1Houston 19 11 (*) 1Fort Worth 19 11 (*) 1

Source: Based on data from National Association of Home Builders, 1977.

'* Not Applicable

There are numerous ways that the energy can be met in

the different climates 0 Table 4 illustrates three alternative ways of

the energy in three climates~

Resistance

with Heat

and

the sea-

:rable 6sum,marizes the results for

with an electric heat PumP0 column

Banal of (heat pumps in the

mode in tell climates ~ ~rhese COPs are based on Oak National

# s simulation of 8.vELtls.ble efflcient heat pumps in ten eli."".

mates ~Neal, 1 The COP for a heat pump is as 10

lower than can be achieved models, to account

heat losses in the associated with the heat pump*

pump

~12~15

Table 40 of theGas-Heated Homes in Three Locations

Location

window area a..ndR-19 wall insulatiou@

2~ Windows redistributed so that south window areaincreased and east~ west~ and northwindow area 25; double R-38

and R-9 wall 1nsulation$

3@ Active solar domestic water sysA.&.~""-"'~&Il>;!IIii&; R-38 and R-ll wall in$ulation~

double

.Atlanta 1 ~

R-38window area and

..... """"'."""~ ..""fl,~, R-19 wall and R-ll

20 Windows redistributed so that south window areaincreased 75 and east~ west~ and noth win~

dow area decreased 25 ; double ; R~30 ceil~

s R~ll wall and R-ll floor insulation~

3>;> Active solar domest:K.c water ~ double~4~;.a.o11.ll"'''ll.ll.,,@O,; R.--19 and R--ll wall j snd R-7 floor insula-

Houston 10R~30

w'indow area andand R=11 wall insulat1on~

double

2@ Active solar dmestic waterR~ll wall insulation~

and

3@ Other alterna.tives ~ such as solar andredisI·:tlrut:ton of <windoW's not evaluated for Houstoo®

Source u of

NOTES The average window area is 15 percent of the total floorarea @ The windows are distributed among the exte-rior walls ~

storm%flith little

tion of the house @

f The active solar domestic water is assumed to besized at 60 percent of the water load in a 1,500square foot house for the purpose of this 111ustratioD$

Floor insulation is noted in Atlanta ~

areas where crawl space baaeme.nts areand all

~

Table 5 Results of the Life Cycle Cost Analysis of Energy Conservation Measures forSingle-Story Houses Heated by Electric Heating (Other Than Heat Pumps)

* * * *' '* 1: '* *Climate Representative Heating Cooling Insulation Levels Number of Conservation Energy BudgetRegion City Degree Degree (R-Value) Glazings Investment Primary Energy

Ceiling Wall Floor 1918 Dollars)

Minneapolis 8,310 530 38 25 t 3 1,160 132$2 38 .. 9(5~260) (370)

2 Chicago 6,130 930 38 25 t 3 1 190 8000 23 .. 5(3,640) (620)

3 Portland 4~190 300 38 25 19 3 1,350 58 .. 5 1102(1,840) (1,010)

3 Washington, D.. C", 4,210 1,420 38 25 t 3 1,190 53",1 15~8

Atlanta f(1 ,980) (1,010)

4 3,100 1,590 38 19 19 3 1,433 39 .. 6 11 .. 6(1,230) (1,130)

4 Fresno 2,650 1,670 38 19 t 3 1,200 38.,6 11 .. 4(710) (1,220)

5 Burbank 1,820 ~ 620 ~ 30 19 t 2 160 15 .. 1 4~4

(110) (36 Phoenix 1,550 3,510 3B 19 t 3 1,280 38\\l5 11 .. 3

(320) (2,960)6 Houston 1,430 2,890 30 19 t 3 1,280 33 .. 6 9.. 9

(360) (2,240)7 Fort Worth 2,830 2,590 38 19 t 3 1,280 43 .. 0 12 .. 6

(810) (2 t 030)

* Heating and cooling degree days base 650F presented; heating degreedays base 530F in parentheses; cooling degree days base 680F inparentheses

..•

"iJ1d

N

I-'N

!-l........

t Not applicable

9 degree days for Los Angeles reported

f Under the ErA Medium Price Projections (December 17 ~ 1978) bothAtlanta used R-ll floor insulation for a conservation investmentcost of $1,330 and a primary energy budget of 40e7 MBtu per squarefoot per year ..

Table 6 - Results of the Life Cycle Cost Analysis of Energy Conservation Measures forSingle-Story Houses Heated and Cooled by Electric Heat Pumps

$: '* * '* * 1: '* 1: *Climate R.epresentative Heating Cooling Insulation Levels Number of Conservation Heat Pump Electrical Energy BudgetRegion City Degree Degree (R-Value) Glazings Investment Seasonal Primary Energy

(in 1978 Dollars) COP** MBtu/ft 2/year MBtu/ft2/yearCeiling Wall Floor

Minneapolis 8~310 530 38 25 t 3 1~160 14'38 98~3

(5 9 260) (370)2 Chicago 6,130 930 38 25 t 3 1,190 1052 544'6 16~1

(3 j 640) (620)3 Portland 4,790 300 38 19 19 3 1,050 11187 34~9 lO~3

(1)840) (1,010):3 Washington, D~C4 4,210 1,420 38 19 t 3 900 14'79 3707 11~1

(1 ~ 980) (lt 010)4 Atlanta 3 t 100 1,590 38 19 11 3 Ij330 1~82 2700 7~9

(1,230) (lfp130)4 Fresno 2,650 IJ670 38 19 t 3 1 280 2~O2 28~6 8&4

(770) (lj220)5 Burbank 1,820 620 30 11 t 2 520 2~O2 14~6 4~3

(170)T (6 Phoenix 1~550 3~510 38 19 t 3 1,280 192 364'0 lOe6

(320) (2,960)6 Houston It 430 2,890 30 19 t 3 1~2S0 1g83 2805 804

(360) (2~240)

7 Fort Worth 2,830 2~590 38 19 t 3 1)280 183 33~9 10~O

(810) (2~O30)

* Heating and cooling degree days base 650F presented; heating degreedays base 53°F in parentheses; cooling degree days base 6SoF inparentheses

t Not applicable

~

~

N

t-ACO

f degree days for Los Angeles reported

indicates the heat-pump system has lower life-cycle costs i.n cool and

cold climates, in spite of the higher initial cost for the heat pump 9

(Pacific Northwest Laboratory, 1979, Appendix I) !II Table 7 illustrates

alternative ways of meeting the design energy budgets that were obtained

for homes heated and cooled by heat pumps in three climates (U.S.

Department of Energy, 1979; Levine et al$' 1979).

Comparison with Current and Past Energy-Conservation Construction

Practice

Figure 1 presents a comparison of fuel requirements for space heat­

ing using natural gas for a large number of different cases. The upper

curve~ labeled "U.S. Stock, Dole 1970," is the best available estimate

of the fuel requirements for space heating the 1970 stock of houses

(Rosenfeld et ale, 1979) e The fourth curve from the top, labeled "HUn

current practice (DOE-2),U is our best estimate of the current construc­

tion practice in houses built after the 1973 oil embargo@ This curve is

based on survey data for the years 1975 and 1977 ~ and on results of

DOE-2 computer calculations performed at LBL (Lokmanhekim ~ a10) 1979;

see also American Institute of Architects, 1979)0 The fifth curve from

the labeled "LBL optimum: medium infiltration," contains the

results of life-cycle costing analysis for gas-heated houses@ The sixth

curve from the top, la.beled "LBL optimum: low infiltration (DOE-2), VI

illustrates the energy requirements for a house with infiltration levels

reduced from 0 @ 6 to 0 @ 2 air changes per hour & For this case, the

is made that mechanical ventilation through a heat recupera-

tor restores the outside air rate to O@6 air changes per hour~

The conclusions from Figure 1 have been stated in an earlier section

of this paper ~ We note here that the energy savings that can be

a.chieved cost-effective energy-conservation measures are enormOUSe

There should be little doubt that UeS. houses can be improved substan­

tial in their thermal performance, and that such improvements can save

money for the consumer ~ The magni.tude of such savings on a national

scale is very large, and can go a long way toward reducing the national

in energy demand

Ta.ble ]@

Location

Chicago

Atlanta

Houston

Illustrative Ways of Meeting the Design Energy Budgetsfor Single Family Electric-Heated Homes in Three Loca­tions

l~ Average window area and distribution*; triple glazingR-38 ceiling and R-25 wall insulation; heating supplied by aheat pump$

2. Windows redistributed so that south facing window areaincreased by 36 percent and east, west, and north facingwindow area decreased by 12 percent; triple glazing; R-38ceiling and R-19 wall insulation; heating supplied by heatpumpe

3. Active solar domestic water heating systemf ; doubleglazing; R-38 ceiling and R-25 wall insulation; heating sup­plied by electric resistance~

window area and distribution*; triple~glazingt;__ .~~~_u~, R-19 wall and R-ll floor insulation'; heating

heat pump!/)

2 $ Windows redistributed so that south facing window areaincreased by 80 and east, west, and noth facing win-dow area decreased 27 percent; doublecglazing; R-38 ceil-

, R-19 wall and R-ll floor insulation~*

domestic water heating systemT; doubleR-ll wall, and R-7 floor insula­electric resistance@

window area and distribut ; triple glazingt;__ .~-~~~M~$ R-19 wall insulation; heating supplied by heat

pump~

2@ Active solar dmestic waterR-ll wall insulation&

R-19 ceiling and

Source: U@ S@ of , 1

NOTES:

(Notes to Table 7 cont'd)

* The average window area is 15 percent of the total floorareSe The windows are distributed equally among the exte­rior walls@

t Double glazing plus storm windows can substitute for tri­ple glazing with little change in the design energy consump­tion of the house@

f The active solar domestic water heating is assumed to besized at 60 percent of the water he,-'ting, load in aI, 500square foot house for the purpose of this illustration.

§ Floor insulation is noted in Atlanta, Georgia and allother areas where crawl space basements are usede

RESIDENTIAL SPACE HEATING

6000

. "", \OOt.-21

09"~u~ '. LO \t\

~

/ %

~/ %

~

%

~

2000 3000 4000 5000

Celsius degree day (18.3°C)

J

1000

$

~

30

20

60 t ~

50

~

....... ~

..............

""'-

N

l-JN@

NN

FIGURE Ie Fuel use for single-family residential space heating XBL 795 -1396

KEY ISSUES

The use of performance standards raises a number of equi ty and

enforcement issues not posed by prescriptive standardse Some of these

issues involve the philosophy of using a performance standard concept

and the objectives of the legislative mandate which establishes such

standards (e.g~, encouraging the use of renewo.ble energy resources) ~

Performance standards are a new phenomenon$ They are not in wide

use anywhere) and even where they have been recently put in limited use,

there has not been enough experience to raise all the important ques­

tions ~ Undoubtedly, the use of nationwide performance standards will

spur further debate on issues of fairness and effectiveness@ We discuss

Del0w some of the issues which have become apparent during the analysis

UL res1dential standards~

The energy budget provides a means of comparing different building

designs in terms of energy consumption 0 It is based on a "design"

calculation--that is, it is calculated based on variations in design

of the building, rather than on changes in the behavior of

its occupants ~ There is no implication that a building with a design

energy budget of 40,000 Btu per square foot per year will be required to

use 40,000 Btu per square foot per year* The energy budget merely

the amount of energy the would be expected to use if

under standard conditions~

The size of the on the assumptions originally incor-

or later to the building energy-use simulation model 9

minor changes in the assumptions can produce sig-

nificant in the energy budget$ This dependence on model assump-

tions is less than it may seem0 What is important is not the

actual number but the set{s) of energy-conservation measures con­

sistent with a given energy budget$ That is) a budget of 40,000 Btu per

square foot per year really represents the set of all buildings which,

when simulated on the building model with standard assumptions, result

in a energy use of 40,000 Btu per square foot per year@ All

buildings with less predicted energy use

those that exceed it fail to comply~

with this budget, while

We see from this discussion that the absolute accuracy of the model,

and the degree of realism of the assumptions, are not nearly as impor­

tant as the relative accuracy. For the purpose of life-cycle cost

modeling, we require accurate predictions of the changes in energy use

which result from a conservation option, so we can evaluate the present

value of energy-cost savings and compare them with the cost of the meas­

ure. Similarly, for compliance with the code, we need to know the rela­

tive change in energy consumption of the permit applicant's house com­

pared to that of the prototype house@ Again, relative rather than abso­

lute accuracy is important, so long as the same assumptions and simula-

tion models are used in and meeting the

Changes in budget level are more than absolute levellt

This explains apparent budget-setting paradoxes, such as the fact that

lower budget numbers ca.n, under certain circumstances , represent a

weaker standard~ An example is the effect of that people set

their thermostats lower to save energy @ This results in a

reduction in use, but it also smaller energy sav-

ings from conservation measures~ This the cost-effectiveness of

the last conservation measure so that it is from the list& The

(i@e~~ budget is lower than one

where a thermostat set was used, but the standard is weaker

because this energy a house with fewer conservation

measures~

Thus, the result of the energy budget-setting process for

residences is the between the budget level and all sets of

conservB. tion measures of the corresponding house. The energy budget

itself has if rules are (prototype descriptions)

standard conditions, energy models, and accompanying

gggYoWlV"",.a..,VIU'o) to derive sets of measures

which are consistent with it, or to test the compliance of sets

of energy-conservation measures$

Comparisons of Computer __~ __ to Building Energy Use

The cost-effectiveness of the energy standards is determined by

simulations performed on the DOE-2 building energy analysis model@ Are

these predictions realistic?

One may test program accuracy by comparing simulations of the same

house using different programs~ There are a number of public-domain com­

puter programs that model home heating and cooling loads $ If the

results of all the programs agree~ then their joint prediction is more

credible than that of a single program 0 If they disagree, the form of

the discrepancy can often provide insight into the building heat­

transfer problem or to possible errors in the computer programs&

We have compared the results of DOE-l and DOE-2 with simulations of

TWOZONE and BLAST, performed at LBL, and with NBSLD runs performed at

NBS and LBL~ The results of several tests

10 ) between all programs for

show good agreement

houses in which solar

are small compared to total heating load (Gadgil, Goldstein, Kam-

merud, and Mass, 1979; Gadgil, Goldstein, and :Mass, 1979)~ More recent

results ha.ve reduced the between TWOZONE and

DOE-2 on cooling loads, and also somewhat lessened the disagreement on

loads in warm sunny climates@ We have also found good agreement

among DOE-2, and TWOZONE for masonry (Pacific Northwest

, 1

There continues to be a need to compare the results with

of residential build-of a statisticalthe energy

checks on test houses) have shown good

a statistical sample would provide important informa-

tion about the between the predicted energy b~dgets and

those obtained (or to be obtained) in the real world~ This

information is in assessing the degree to which

BEPS or other energy-conservation policy initiatives are likely to

reduce actual energy use@ We have undertaken some modest work along

these lines, and we tha.t DOE will a more extensive

and program the of BEPS~

standards ins tead of

to credit

One key argument for the use of

s is the of

passive solar techniques~

builder can use solar

through other features (

For instance, with a performance standard, a

from south windows to offset heat loss

north win~ows) for example) $

Given an evaluation method (for example~ the DOE-2 program and a set

of assumptions), the standard a credit for passive

techniques to the extent that the program handles the heat

flows in passive Present evidence suggests that DOE-2 shows

significant savings potentials from systems in all

climates, that DOE-2 may underestimate these

The ions appear to be than those in other public-

domain programs, such as and TWOZONE $ Therefore, the use

of the will result in credits for pas-

sive solar~ (It may also, we ) result in in DOE-2 and

other programs so that solar systems are more accu-

simulated@) To be useful~ these credits must be evaluated in a

form so that can be used in trade-off with sim-

such as heat .......loss methods ~ for the of

builders who will not use DOE-2@

Once constructed t solar will use less

energy than other which with the energy Pas-

sive houses better as the thermostat range is increased~

The float band used in the evauation 80 Department of

is too small to take full of the heat storage in

a However, in our !J credi the passive

with their full :tal in use is not appropriate

for several reasons@ First) it is to allow buildings

labeled to take credit for in @g@, lower

thermostat set ) which are denied to other houses~ Second, if

credits are will be used to t lower insulation

levels~ is reduction in insulation levels will move the house

away from its ow, cost A that uses as much

energy with a widely thermostat as a conventional house with a

conventional thermostat would be a very If subsequent

occupants tried to heat it to 700F, would find it to be much more

inefficient than the homet

Optimal passive houses will not have minimum design

energy budgets~ A passive house w0uld probably fall somewhat

below the ) in terms of energy budget, but

would consume substantially less energy in use~ Another passive house

might have an even lower , but energy use0 That is, while

passive solar design will be more energy-efficient than complying with

the budget, the evaluation method will ensure that a passive

house will not use more energy for space than a conven-

tional house, even under conventional schedules@

with the-------- -- -- ----- --~-ts are derived a house

with a set of a simulation modele In

can be demonstrated the same the

is run the simulation model with the same

set of and the energy use determines whether the

will use a procedure

use the insu-

Variations from the insulation levels

For , more window area may be offset

less insulation in one element more in another@

be handled s design-heat-loss tech-

of the simulation model results will

In , we that very few

this Most builders will

lation standards in the

will be

The simulation wodel can handle trade-ofis, such as

variations in windo\i17 orientation» mass @

trade-off rules based on these simulations should be developed@ Other

trade-offs may be the scope of the model~ Changes in

or contours to minimize wind pressure on the house

2",12 27

can have a influence on energy use reducing infiltratione How-

evert present are incapable of computing the

extent of such The enforcement agency will have to develop

appropriate methods for these of measures $ Otherwise)

each builder will to use a different method to qualify his par-

ticular energy-saving option while code officials handle ident­

ical measures inconsistently~ This will lead to extra analytic work and

inequitable treatment of some builders$

This example illustra.tes one of the inherent in a perfor-

mance standard: the tools for establishing compliance will never be able

to model all the newest innovations@ Code officials often resist

innovations whose effectiveness cannot be and conclusively

Since one of the purposes of the standard is to

foster innovation, a process should be to facilitate approval

of new One is to to help

the innovator obtain from the code official (if

)@ Another could be to have a process which

screened innovations and those that significant (in

terms of energy to many buildings,

and by DOE$ A prelim-

within a time could result in approval

before final resul ts are obtained 1lI Other

need to be to insure that BEPS fosters rather than

retards innovative

How are Needed?---::=:0---......

costs involves certain qualities of a

house to save energy Inherent in this process is the division of

ies into two classes: those that can be adjusted in the

process ~ g ~ ~ insulation levels and number of glazings)

and those that are held fixed ~g ~) house and house construe"""

The choice of which items to hold fixed and what values to use

for the fixed parameters will affect the level of ; each different

choice will a different energy

There are two approaches to handling a "fixed" parameter@ One is to

require that all houses comply with a budget derived using one value of

that parameter; the other is to derive separate budgets for buildings

with different values of the parameter 0 The first approach has several

advantages~ Foremost amon~ these is flexibility~ Using an analytically

complex performance standard instead of a simple prescriptive standard

increases the builder's flexibility in complying by allowing him to

offset noncompliance with prescriptive limits in some areas against

overcompliance or design changes in others @ Setting separate budgets

for the separate values of a parameter eliminates the builder's ability

to use that parameter ~ The single-budget approach (for each weather

region) is also much easier to derive a.nd administer, since only one

benefit/cost analysis is required and each applicant in a given region

has a single target to hit~

The second approach--different budgets for each value of the fixed

parameter--has the advantage of increasing fairness and political accep-

For ) if a certain of house cannot feasibly com-

with a single standard, then a standard for that type of

house~ set at its own cost minimum, will greater political accep-

tance and cause less interference in selection of house type@

The drawback of the second approach is its administration@ Whenever

a criterion is used to differentiate among houses with different energy

, some will come in with an intermediate case@ For

if there are budgets for one-story and two-story

houses) how does one treat a case with a 1 foot second-floor

room over a 3000-square foot first floor? If there are separate stan­

dards for gas heat and electric heat, how does one classify an electric

heat pump with gas heat?

There are many possible features for which people have suggested

energy budgetse These include frame and masonry construction,

full basement vs@ crawl space or slab floor, two-story houses, one-story

houses, , hi-levels) townhouses, houses with large aspect

ratios, houses with window areas, sites without solar access,

or electric houses, houses heat pumps

or oil heat, houses without air , houses with evaporative

coolers, houses with many bedrooms, houses with special solar features,

and so on @ If all of these were used j the "performance"

nature of the standards would be undermined, and setting them would

involve immense analytic effort~

Resolution of the question of whether s~pa:rate energy budgets are

needed will depend, in part, on the difference between the

design energy budgets and the accompanying sets of energy-conservation

measures for different values of parameters @ If the selection of the

value of a given parameter has little effect on the building's design

energy budget, then one may fix the parameter in question~ Conversely,

if the value of the parameter has a large effect on the design energy

budget, the best decision will not be For example, our

analysis shows that changes in house , house size, and wall con-

struction (frame or have small effects (less than 10 per-

cent) on the energy , so that may be unnecessary~

The difference between heat pump energy and those for gas heat

is somewhat ~ with heat pumps 10-20 (using

than gas furnaces in most climates, but over 40 percent

in the coldest climates@

How for Different Fuels Be Compared?-~_.......

Great has surrounded the of how to compare the

energy for different fuels $ Two measures are commonly used:

energy and resource energYe This also

discusses a third measure: energy@

The counts the energy content of fuels as

cross the Oil and gas are counted as the energy

content of fuel sold to the is counted as the heat

content of the electric energy transferred past the electric meter@

The resource energy is based on the desire to

conserve energy resources rather than measure the amount of processed

energy sold 0 This also counts the energy needed to

the energy sold@ of this ) such as

that used in the California standards (California Administrative Code

24) count gas and oil exactly as is done in building-boundary

accounting methods, but the heat content of 3 to

account for thermal losses in the power plant@

Critics of the resource-energy approach have argued that it is

oversimplified--that to be fair we must gc further ba.ck through the

economy and include the efficiency of , and transport~

ing fuels, including extraction efficiencies@ They add that too little

is known about the whole process to a.llow evaluation of resource use

factors (resource energy use per unit of building-boundary fuel)~

Proponents of the building-boundary approach also point out that

'8 resource use factor of 3 will encourage the use of scarce

gas and oil fuels over But the resource-energy proponents

insist that the factor of 3 is necessary because elect isn't a

fuel, and that one unit of is worth more than one

unit of fuel since it has been converted to a lower form@

A third the energy method) reduces some of

these In this method, one fuel, say gas, is counted at

levels a.nd other fuels are their

relative to gas~ The method is the most consistent with

the of bas energy on a cos t minimum 0

This is the taken in the rest of the performance standard

, since it energy ts which are propor-

tional to fuel costs@ If energy ts are to

fuel costs, then tradeoffs in the that use an extra price .....

unit of one fuel in for one less price-weighted unit

of another fuel neither the energy nor the fuel costs @

the will be to design his

to achieve with the standard in a cos

manner@

The

Btu of coa.l

factors the ion that the building-

allows the substitution of electricity for

fuels~ The avoids one

the same as one Btu of gas or one Btu of oil ~

Further, if the government seeks to reduce conslmlption of a specific

fuel, say oil, then it can act as if this fuel had a higher price@ This

price will affect the energy-budget weight~ but it will also affect the

tradeoffs between use of the fuel and conservation measures$ Thus, sav­

ing a scarce fuel by fuel substitution can be treated on a uniform

economic basis with saving the fuel by conservation$

ONGOING RESEARCH

Continuing analysis addresses a number of specific technical issues

involved in the process of standard setting for the energy performance

of new single-family residential buildings~ These include:

o Assessing the effect of jointly setting appliance (including

heating and cooling equipment) and building shell energy­

performance standardsc

o Analyzing the seasonal efficiencies of heating and cooling

equipment in different weather regions and in houses with vary­

amounts of energy conservation48

o Developing two new residential prototypes:

heated basement; townhouse attached on one side~

o

houses"

of the thermal performance of masonry

o Conduc

dow orientation.

thermal mass@

studies on the effects of changing win­

size, conservation measures, and internal

o the energy of "zoned" houses in which

is operated on a schedule in which

the heat is turned off in selected rooms much of the time e

o Investigating advanced energy-conservation options, including

reducing infiltration with a heat recuperator to avoid indoor

air quality problems~

o Comparing computer calculations of residential-building energy

requirements with measured data@

These technical issues have been selected because they are important

to the formulation of a final rule for DOE's Building Energy Performance

Standardse The proposed rule, issued in November 1979, used the results

of the analysis of residential life-cycle costs that are presented in

this papero We anticipate that the final rule will also reflect addi­

tional knowledge and information gained by continuing analysis of the

issues identified abovee Many individuals, some opponents of

energy standards for buildings) have noted that one of the most impor­

tant results of developing the standards has been an increased knowledge

of: the thermal beha.vior of the conservation measures that

are cost-effective in different of the nation; and the gaps in

our knowledge that must be filled to produce better standards for the

future~ To the extent that the results of the many studies done

for the of on the standards become widely

available to the and communities, they could be effec-

tive even without a heroic effect to implement theme

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!@ Achenbach, P.R@, and CGWiIl Coblentz~ 1963@ "Field Measurements of

Air Infiltration in Ten Electrically Heated Houses." ASHRAE Transac­

tions 69:

2 G American Institute of Architects @ 1979 $ Phase Two Report--For the

Development of Energy Performance Standards for New Buildings: Com­

mercial and Multi-Family Residential Buildings@ City, State:

3411 BLAST--The Buildings Loads Analysis and System Thermodynamics Pro­

gram~ Technical Report E-1530 [City, State:C E R L]@

4@ Building Energy Analysis Group, Lawrence Berkeley LaboratorYG 1979~

"DOE-2: A New State-of-the-Art Computer Program for the Energy

Utilization Analysis of Buildings @ if Paper presented at the Second

International CIB Symposium on Energy Conservation in the Built

Environment, May 28-June 1, Copenhagen, Denmark~

5~ Gadgil, AeJ@9 ~ al~ 1978e TWOZONE User's Manuale Berkeley, Calife:

Lawrence Berkeley Laboratory (LBL-6840)$

6@ Gadgil, A@ , D@ Goldstein, R@ Kammerud, and J$ Mass~ 1979@ "Residen-

tial Simulation Model Comparison Using Several Building

Programs U0 In Proceedings of the Fourth National

Passive Solar Conference, October, Kansas City~ Mo@

7~ , A0~ D~ Goldstein, and J@ Mass@ 1 0 UA Heat and Cooling

Loads of Three Building Simulation Models for Residences:

TWOZONE, DOE-l and NBSLDi&>u Proceedings of the International Confer-

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8@ Goldstein, D@B$' M@D@ Levine, and J@ Mass@ 1979$ Residential Energy

Standards: Methodology and Assumptions @ Berkeley,

$: Lawrence Berkeley Laboratory (LBL-9110)$

9~ Hastings, R. S. 1977~ Three Proposed Typical House Designs for

Energy Conservation Research. Washington, D.C~: National Bureau of

Standards@ (77-1309)@

10. Kusuda, T. 1976. NBSLD, Computer Program for Heating and Cooling

Loads in Buildings @ Na tional Bureau of Standards Science Series,

Vol. 69~ Washington, D~C.: National BUl~au of Standards.

11. Levine, M.D. and D.B@Goldstein.1979. H__"[TitleofCh.4].

In Economic Analysis of Proposed Building Energy Performance Stan­

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and Oak Ridge National Laboratory. (See also Appendices, 10)

September. City State.: Pacific Northwest Laboratory (PNL-3044).

12. Levine, MeDe, DeB@ Goldstein, and D@ O'Neal~ 1979. Residential

Energy Performance Standards: Comparison of HUD Minimum Property

Standards and DOE's Proposed Standards@ Berkeley, Calif@: Lawrence

Berkeley Laboratory (LBL-9817)@

13 @ National Association of Homebuilders ~ 1977 ~ A National Survey of

Characteristics and Copstruction Practices for all Types of One-

Houses~ ,Statee: National Association of Homebuilderse

14e O'Neal, Dennis~ 1979@ Personal communicatione August~

15 Resources for the Future * 1979 @ The Next Twenty Years $

,D~C~: Resources for the Future~

16w Rosenfeld, A@ H@, W0 G@ Colborne~ C~ D@ Hollowell, L. J@ Schipper,

Bo Adamson, MQ Cadiergues) Gilles Olive) Bengt Hidemark, Gf3 S&

~ H~ Ross, N@ Milbank, and Me J0 Uyttenbroeck~ 19790

Energy 'Use Compilation and Analysis (BECA): An Interna­

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Laboratory (LBL-8912)@

170 ,L{9, J@ M@ Hollander» M0 Levine, and P@ Po Craig@ 1979&

"The National Energy Conservation Policy Act: An Evaluation~n

Natural Resources Journal. Vol@ 19, P 765 (October, 1979)&

18. U.S@ Department of Energy. 1979@ Notice of Proposed Rulemaking for

the Building Energy Performance Standardse Washington, D.C.: U.S.

Department of Energy@