U.S. Department of Energy

Energy Efficiency and Renewable Energy

Bringing you a prosperous future where energy is clean, abundant, reliable, and affordable

Building Technologies Program

T OF ENERGY

DEPARTMEN

U

E

NITED STAT S OFA ERICA

M

February 2005 • NREL/TP-550-37529

Building America Research Benchmark

Definition, Updated December 29, 2004

Robert Hendron

National Renewable Energy Laboratory
National Renewable Energy Laboratory 

1617 Cole Boulevard, Golden, Colorado 80401-3393 

303-275-3000 • www.nrel.gov 

Operated for the U.S. Department of Energy 

Office of Energy Efficiency and Renewable Energy 

by Midwest Research Institute • Battelle 

Contract No. DE-AC36-99-GO10337

February 2005 • NREL/TP-550-37529 

Building America Research 

Benchmark Definition, Updated 

December 29, 2004 

R. Hendron 

Prepared under Task No. BET5.8004 
NOTICE

This report was prepared as an account of work sponsored by an agency of the United States 

government. Neither the United States government nor any agency thereof, nor any of their employees, 

makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, 

completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents 

that its use would not infringe privately owned rights. Reference herein to any specific commercial 

product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily 

constitute or imply its endorsement, recommendation, or favoring by the United States government or any 

agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect 

those of the United States government or any agency thereof. 

Available electronically at http://www.osti.gov/bridge

Available for a processing fee to U.S. Department of Energy 

and its contractors, in paper, from: 

U.S. Department of Energy 

Office of Scientific and Technical Information 

P.O. Box 62 

Oak Ridge, TN 37831-0062 

phone: 865.576.8401 

fax: 865.576.5728 

email: mailto:reports@adonis.osti.gov

Available for sale to the public, in paper, from: 

U.S. Department of Commerce 

National Technical Information Service 

5285 Port Royal Road 

Springfield, VA 22161 

phone: 800.553.6847 

fax: 703.605.6900 

email: orders@ntis.fedworld.gov

online ordering: http://www.ntis.gov/ordering.htm

Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste
iii

TABLE OF CONTENTS 

Benchmark House Specifications 1

 Building Envelope 1 

 Space Conditioning/Air Distribution Equipment 9 

 Domestic Hot Water 12 

 Air Infiltration and Ventilation 18 

 Lighting Equipment and Usage 19 

 Appliances and Other Plug Loads 22 

 Site Generation 29 

Operating Conditions 29 

Reported Energy Use and Energy Savings 32 

References 36 
1

Building America Research Benchmark Definition 

National Renewable Energy Laboratory 

Updated December 29, 2004 

To track progress toward aggressive multi-year whole-house energy savings goals of 40-70% and onsite 

power production of up to 30%, the U.S. Department of Energy (DOE) Residential Buildings Program 

and the National Renewable Energy Laboratory (NREL) developed the Building America Research 

Benchmark in consultation with the Building America industry teams. The Benchmark is generally 

consistent with mid-1990s standard practice, as reflected in the Home Energy Rating System (HERS) 

Technical Guidelines (RESNET 2002), with additional definitions that allow the analyst to evaluate all 

residential end-uses, an extension of the traditional HERS rating approach that focuses on space 

conditioning and hot water. A series of user profiles, intended to represent the behavior of a “standard” 

set of occupants, was created for use in conjunction with the Benchmark. 

Benchmark House Specifications 

The following sections summarize the definition of the Benchmark, updated for the FY05 Building 

America subcontracts. A comprehensive description of other important Building America reference 

houses (Builder Standard Practice and Regional Standard Practice), along with guidance for using hourly 

simulation tools to compare an energy efficient prototype house to the various base case houses, can be 

found in the NREL technical report addressing systems-based performance analysis of residential 

buildings (Hendron et al. 2004). NREL and other Building America partners have also developed a series 

of tools, including spreadsheets with detailed hourly energy usage and load profiles, to help analysts 

apply the Benchmark quickly and in a consistent manner. These tools can be found on the Building 

America web site (http://www.eere.energy.gov/buildings/building_america/pa_resources.html). 

Any element of the Benchmark definition that is not specifically addressed in the following sections is 

assumed to be the same as the Prototype house. Because the definition is intended to be software-neutral, 

certain elements of the Benchmark cannot be modeled directly using every common simulation tool. The 

full Building America Performance Analysis Procedures (Hendron et al. 2004) includes application notes 

addressing some practical implementation issues that may be encountered when simulating the 

Benchmark using DOE-2.2 or EnergyGauge. 

Building Envelope 

All building envelope components (including walls, windows, foundation, roof, and floors) for the 

Benchmark shall be consistent with the HERS Reference Home as defined by NASEO/RESNET in the 

“National Home Energy Rating Technical Guidelines,” dated September 19, 1999 (RESNET 2002). 

These requirements are summarized below, along with a few minor clarifications and additional 

requirements. References to U-values in the 1993 Model Energy Code (MEC) have been updated to 2003 

International Energy Conservation Code (IECC), because the corresponding U-values are identical and 

the IECC is more readily available (ICC 2003). 
2

The Benchmark envelope specifications are as follows: 

• The same shape and size as the Prototype 

• The same area of surfaces bounding conditioned space as the Prototype with the exception of the 

attic, which shall be insulated at the attic floor and have a ventilation area of 1 ft2

 per 300 ft2

ceiling area, regardless of the Prototype attic design 

• The same foundation type (slab, crawl space, or basement) as the Prototype 

• The same basement wall construction type as the Prototype (e.g., masonry, wood frame, other) 

• No sunrooms 

• No horizontal fenestration, defined as skylights, or light pipes oriented less than 45 degrees from 

a horizontal plane 

• Window area (AF) determined by Equation 1 for detached homes and by Equation 2 for attached 

homes: 

Equation 1: AF = 0.18 x AFL x FA

Equation 2: AF = 0.18 x AFL x FA x F 

 where 

AF = total window area (ft2

) 

 AFL = total floor area, including basement (ft2

) 

FA = (exposed thermal boundary wall area)/(total thermal boundary wall 

area) 

F = (total thermal boundary wall area)/(total thermal boundary wall area 

+ common wall area), or 0.56, whichever is greater 

 and where 

total thermal boundary wall is any wall that separates directly or indirectly 

conditioned space from unconditioned space or ambient conditions, 

including all insulated basement walls but not including unvented 

crawl space walls; 

exposed thermal boundary wall is any thermal boundary wall not in contact 

with soil; and 

common wall area is the total area of walls adjacent to another conditioned 

living unit, including basement and directly or indirectly conditioned 

crawl space walls. 

• The window area calculated above is distributed with the same proportion on each wall and on 

each floor as the Prototype house. The energy use is calculated with the Benchmark house in each 

of four orientations rotated in 90o increments relative to the Prototype orientation (+0o, +90o, 

+180o, +270o), and the average of these four cases is used to represent the energy use of the 

Benchmark. 

• Thermal conductance of all thermal boundary elements equal to the requirements, expressed as U 

values, of Paragraph 502.2 of the 2003 IECC (ICC 2003), as summarized below. Unless 

otherwise specified, these U-values are for entire assemblies, including sheathing, framing, 

finishes, and so on. 
3

o U-value (Uw) for the opaque fraction of exterior walls from Table 1 or 2, as appropriate. 

o The U-value and solar heat gain coefficient for vertical fenestration, including windows 

and sliding glass doors, shall be determined using Table 3. The values in Table 3 were 

calculated based on the HERS methodology for determining maximum window U-value, 

assuming a floor area to wall area ratio of 1.0. If the simulation tool uses a window 

library, a window that approximately matches the UF and SHGC shall be selected, and 

the frame R-value shall be increased or decreased until the overall window UF matches 

the value in Table 3. 

Table 1. Opaque Wall U-Values (Uw) for Detached Homes (Excerpted from ICC 2003) 

 

1

 See Solar Radiation Data Manual for Buildings (or the “Blue Book”) published by the National Renewable Energy 

Laboratory (NREL 1995) (http://rredc.nrel.gov/solar/old_data/nsrdb/bluebook/). 

Annual Heating Degree Days Base 

65 (HDD65) from Nearest Location 

Listed in Chapter 9 of ASHRAE 

Standard 90.2 or NREL’s Solar 

Radiation Data Manual1

Uw Air to Air, 

Includes 

Framing 

(Btu/hr-ft2-oF) 

> 13000 0.038 

9000-12999 0.046 

6500-8999 0.052 

4500-6499 0.058 

3500-4499 0.064 

2600-3499 0.076 

<2600 0.085 
4

Table 2. Opaque Wall U-values (Uw) for Attached homes (Excerpted from ICC 2003) 

Heating Degree Days Base 65 

(HDD65) from Nearest Location 

Listed in Chapter 9 of ASHRAE 

Standard 90.2, or NREL’s Solar 

Radiation Data Manual

Uw Air to Air, 

Includes 

Framing 

(Btu/hr-ft2-oF) 

>9000 0.064 

7100-8999 0.076 

3000-7099 0.085 

2800-2999 0.100 

2600-2799 0.120 

<2600 0.140 

Table 3. Vertical Fenestration U-values (UF) and Solar Heat Gain Coefficients (SHGC) 

HDD65 from Nearest Location 

Listed in Chapter 9 of ASHRAE 

Standard 90.2, or NREL’s Solar 

Radiation Data Manual

UF Air to Air, 

Includes Framing 

and Sash 

(Btu/hr-ft2-oF)

SHGC, 

Includes 

Framing and 

Sash

≥7000 0.36 0.32 

6000-6999 0.39 0.32 

5000-5999 0.46 0.58 

4000-4999 0.53 0.58 

3000-3999 0.58 0.58 

2000-2999 0.62 0.65 

1000-1999 0.79 0.65 

≤999 1.00 0.79 
5

o U-value of an insulated floor above a vented crawl space or other unconditioned space 

shall be as specified in Figure 1 (excerpted from ICC 2003). 

o U-value of insulated walls in an unvented crawl space shall be as specified in Figure 2 

(excerpted from ICC 2003). This U-value represents the combined effect of wall 

components and the surface air film, but it does not include adjacent soil. 

o U-value of insulated basement walls shall be as specified in Figure 3 (excerpted from 

ICC 2003), and the insulation shall be located on the interior surface of the walls. This 

U-value represents the basement wall assembly, including the surface air film, but it does 

not include ground effects. 

o R-value and depth of slab edge insulation for slab-on-grade construction shall be as 

specified in Figure 4 (excerpted from ICC 2003). This R-value is for rigid foam 

insulation and does not include the slab itself or ground effects. 

o U-value of insulated roof/ceiling shall be as specified in Figure 5 (excerpted from ICC 

2003). If the Prototype includes an attic, the Benchmark shall have an unconditioned 

attic with insulation at the attic floor. 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Annual Heating Degree Days, Base 65

U0 (Btu/h-sqft-oF)

Figure 1. U-value of floor over unconditioned space (excerpted from ICC 2003) 

Heating Degree Days 

(HDD) Maximum U0-Factor

0 - 1,000 0.08

1,001 - 2,500 0.07

2,501 - 15,500 0.05

15,501 - 16,500 0.05 - [(HDD - 15,500) x 0.00001]

> 16,500 0.04
6

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Annual Heating Degree Days, Base 65

U0 (Btu/h-sqft-oF)

Figure 2. Unvented crawl space wall U-value (excerpted from ICC 2003) 

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Annual Heating Degree Days, Base 65

U0 (Btu/h-sqft-oF)

Figure 3. Basement wall U-value (excerpted from ICC 2003) 

Heating Degree Days 

(HDD) Maximum U0-Factor

0 - 499 None Required

500 - 2,000 0.15

2,001 - 5,000 0.21 - (HDD x 0.00003)

> 5,000 0.06

Heating Degree Days 

(HDD) Maximum U0-Factor

0 - 1,499 None Required

1,500 - 4,500 0.205 - (HDD x 0.0000233)

4,501 - 8,500 0.11125 - (HDD x 0.0000025)

8,501 - 9,000 0.6 - (HDD x 0.00006)

> 9,000 0.06
7

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Annual Heating Degree Days, Base 65 (In Thousands)

R-Value (h-sqft-oF/Btu)

Unheated Slab

Heated Slab

2 ft 4 ft

Figure 4. Slab insulation R-value and depth (excerpted from ICC 2003) 

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Annual Heating Degree Days, Base 65

U0 (Btu/h-sqft-oF)

Figure 5. Roof/ceiling assembly U-value (excerpted from ICC 2003) 

Heating Degree Days 

(HDD) Maximum U0-Factor

0 - 2,500 0.05 - (HDD x 0.0000056)

2,501 - 3,900 0.036

3,901 - 6,000 0.036 - [(HDD - 3,900) x 0.00000476]

6,001 - 16,000 0.026

16,001 - 16,500 0.026 - [(HDD - 16,000) x 0.000002]

> 16,500 0.025

Heating Degree Days 

(HDD) Minimum R-Value

0 - 499 None Required

500 - 4,500 R-6

4,501 - 19,000 2.5862 + (HDD x 0.000759)

> 19,000 R-17

0 - 2,499 None Required

2,500 - 4,500 R-4

4,501 - 19,500 1.0 + (HDD x 0.000666)

> 19,500 R-14

Heated Slab

Unheated 

Slab
8

• No external shading at any time from roof projections, awnings, adjacent buildings, trees, etc. 

Basic architectural features such as attached garages and enclosed porches shall be included in the 

Benchmark model, but the model shall not include window shading effects from these features. 

• No self-shading shall be modeled for the Benchmark. 

• Total area of opaque exterior doors is equal to 40 ft2, facing north, with door U-value equal to 

0.20 Btu/hr·ft2

·oF (air to air). 

• Solar absorptivity is equal to 0.50 for opaque areas of exterior walls and 0.75 for opaque areas of 

roofs. 

• Total emittance of exterior walls and roofs is equal to 0.90. 

• The above-grade exterior walls shall be light-frame 2x4 or 2x6 wood construction with sufficient 

insulation to achieve the correct overall U-value. The framing factors in Table 4 are 

representative of typical construction practices, and shall be used as inputs for the Benchmark 

model. 

• Interior partition walls shall be light-frame (2x4) wood construction. 

• Masonry floor slabs shall have 80% of floor area covered by R-2 carpet and pad and 20% of floor 

area directly exposed to room air. 

Table 4. Benchmark Framing Factors 

Frame Framing 

Spacing Fraction 

Enclosure 

Element 

(inches o.c.) (% area) 

Walls 16 23% 

Floors 16 13% 

Ceilings Below 

Unconditioned Space 24 11% 
9

Space Conditioning/Air Distribution Equipment 

Space-conditioning equipment type and efficiency for the BA Benchmark shall meet the following 

requirements: 

• The minimum National Appliance Energy Conservation Act (NAECA) efficiency in effect on 

January 1, 1992, for the same type of heating, ventilating, and air-conditioning (HVAC) 

equipment found in the Rated Home, except that the efficiencies given in Table 5 are assumed 

when 

(a) A type of device not covered by NAECA is used in the Prototype. 

(b) The Prototype is heated by electricity using a device other than an air-source heat pump. 

(c) The Prototype does not have a heating system, and there is at least one month in which 

heating is required (see the section on Operating Conditions). 

• If the Prototype does not have a cooling system, both the Benchmark and Prototype shall be 

modeled assuming a standard 10 SEER air conditioner. 

• If the simulation tool requires the use of EER instead of SEER for a heat pump or air conditioner, 

then the EER for the Benchmark shall be calculated using Equation 3. If the actual EER for the 

Prototype is not readily available, Equation 3 may also be used to make an approximate 

conversion from SEER to EER (Wassmer 2003): 

 Equation 3: EER = -0.02 x SEER2

 + 1.12 x SEER 

• Heating and cooling equipment (including the air handler) shall be sized using the procedures 

published by the Air Conditioning Contractors of America (ACCA). (See 

www.accaconference.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=ACCOA&Cat

egory_Code=M) 

• The Benchmark shall not have a whole-house fan. 

• The Benchmark shall have no supplemental dehumidification beyond that provided by a standard 

air conditioner. 

• The Benchmark air handler shall have power consumption equal to 0.00055 kW/cfm. 

The air distribution system in the Benchmark shall have the properties listed in Table 6. The location of 

the ductwork in the Benchmark is based on the type of foundation used for the Prototype. If the 

simulation tool does not permit the input of duct specifications to this level of detail, then two values (one 

for heating, one for cooling) of seasonal distribution system efficiency (DSE) shall be estimated and 

applied to the heating and cooling system efficiencies to represent typical losses from ducts. The DSE 

values shall be determined using Table 6 and the procedures in the Draft ASHRAE Standard 152P 

(ASHRAE 2001b). A spreadsheet developed by Lawrence Berkeley National Laboratory (LBNL) and 

modified by NREL is posted on the Building America Web site to assist with this calculation. 
10

Table 5. Benchmark Space-Conditioning Equipment Efficiencies 

Prototype Equipment Function Benchmark Space-Conditioning Device 

Electric or No System Heating 6.8 HSPF Air Source Heat Pump 

Non-Electric Boiler Heating 80% AFUE Gas Boiler 

Non-Electric Warm Air Furnace or 

Other Non-Electric Heating Heating 78% AFUE Gas Furnace 

Any Type or No System Cooling 10 SEER Electric Air Conditioner 
11

Table 6. Duct Locations and Specifications for the Benchmark

Benchmark Duct Specification Prototype 

Foundation Type One-Story Two-Story or Higher 

Supply Duct Surface Area 

(ft2

) All 0.27 x FFAa

 0.20 x FFA 

Return Duct Surface Area 

(ft2

) All 

0.05 x Nreturns x FFA 

(Maximum of 0.25 x FFA) 

0.04 x Nreturns x FFA 

(Maximum of 0.19 x FFA) 

Supply Duct Insulation 

(Conditioned Space) All R-3.3 

Return Duct Insulation 

(Conditioned Space) All None 

Supply/Return Duct 

Insulation (Unconditioned 

Space) 

All R-5.0 

Duct Material All Sheet Metal 

Duct Leakage 

(Inside + Outside) 

All 

15% of Air Handler Flow (10% Supply, 5% Return) 

(Percentage lost to each space equal to percentage of 

duct area in that space, as specified below) 

Air Handler Location All Conditioned Space Conditioned Space 

Slab-on-grade or 

Raised floor 100% Atticb 65% Atticb

, 35% Conditioned 

Space 

Crawl space 100% Crawl space 65% Crawl space, 35% 

Conditioned Space Supply Duct Location 

Basement 100% Basement 65% Basement, 35% 

Conditioned Space 

Slab-on-grade or 

Raised floor 100% Atticb

 100% Atticb

Crawl space 100% Crawl space 100% Crawl space Return Duct Location 

Basement 100% Basement 100% Basement 

a

 Finished floor area (ft2) 

b If the Prototype does not have an attic, then this percentage of duct leakage in the Benchmark is assumed to be in 

an attached garage. If the Prototype does not have an attached garage, then the leakage is assumed to be in 

conditioned space.
12

Domestic Hot Water 

The assumptions in Table 7 shall be made for the domestic hot water system in the Benchmark. Both 

storage and burner capacity are determined using the guidelines recommended by ASHRAE in the HVAC 

Applications Handbook (ASHRAE 1999); these are based on the minimum capacity permitted by the 

Department of Housing and Urban Development (HUD) and the Federal Housing Administrations (FHA) 

(HUD 1982). Energy factor is the NAECA minimum for the corresponding fuel type and storage 

capacity (DOE 2002a). An example set of Domestic Hot Water (DHW) specifications based on a typical 

three-bedroom, two-bathroom Prototype is shown in Table 8. The “Appliance and DHW” spreadsheet 

developed by NREL automates many of the equations discussed in the following paragraphs and can be 

downloaded from the Building America Web site 

(http://www.eere.energy.gov/buildings/building_america/pa_resources.html). 

NREL has also developed a spreadsheet that calculates the correct DHW inputs for the TRNSYS 

computer program, including standby heat loss coefficient (UA). The spreadsheet also has a 

comprehensive set of inputs and outputs that can be used to help calculate DHW properties for the 

Prototype house (Burch and Erickson 2004). It can be found on the Building America Web site in the 

section for building scientists 

(http://www.eere.energy.gov/buildings/building_america/pa_resources.html). 

Table 7. Characteristics of Benchmark Domestic Hot Water System 

Water Heater Fuel Type in Prototype 

Electric Gas 

Storage Capacity (V) (Gallons) See ASHRAE HVAC 

Applications 1999

See ASHRAE HVAC 

Applications 1999

Energy Factor (EF) 0.93 – (0.00132 x V) 0.62 – (0.0019 x V) 

Recovery Efficiency (RE) 0.98 0.76 

Burner Capacity See ASHRAE HVAC 

Applications 1999

See ASHRAE HVAC 

Applications 1999

Hot Water Set-Point 120°F 

Fuel Type Same as Prototypea

Tank Location Same as Prototype 

a If the Prototype does not have a DHW system, or the hot water system uses solar energy or a fuel other than gas or 

electricity, the Benchmark shall use the same fuel for water heating as that used for space heating. 
13

Table 8. Example Characteristics of Benchmark Domestic Hot Water System Based on a 

Prototype with Three Bedrooms and Two Bathrooms 

Four major end uses are identified for domestic hot water: showers, sinks, dishwasher, and clothes 

washer. The average daily water consumption by end use is shown in Table 9. For showers and sinks, 

the specified volume is the combined hot and cold water. This allows hot water use to fluctuate 

depending on the cold water (mains) temperature.2 Hot water usage for the clothes washer and 

dishwasher were estimated based on several scientific references studied by NREL. For showers and 

sinks, the water usage is based on the average of three domestic hot water studies (Christensen 2000 et al., 

Burch and Salasovich 2002, CEC 2002). The relationship between the number of bedrooms and hot water 

usage was derived from the 1997 Residential Energy Consumption Study (RECS) (DOE 1999). This 

relationship also applies to machine energy for certain appliances, which will be discussed later in this 

report. 

Hourly hot water use profiles for individual hot water end uses are shown in Figures 6 through 8. For 

software tools that do not accept this level of detail, the combined hourly hot water profile may be used, 

as shown in Figure 9. 

This combined hourly profile is based on a 1990 study conducted by Becker and Stogsdill (1990), which 

included hot water data from several earlier studies. The profiles for the clothes washer and dishwasher 

are based on the electrical end-use measurements in the ELCAP study conducted in the Pacific Northwest 

by the Bonneville Power Administration in the 1980s (Pratt et al. 1989). It is assumed that the 

normalized hourly profiles for electricity and hot water are the same for these two appliances. The 

shower and sink profile was derived by subtracting the hourly clothes washer and dishwasher hot water 

consumption from the combined hourly hot water usage for a three-bedroom house in Memphis, 

Tennessee. 

 

2

 The clothes washer in the Prototype may also consume a variable amount of hot water depending on mains 

temperature if it uses a thermostatic control valve to adjust the proportion of hot and cold water necessary to 

maintain a certain wash temperature. However, the Benchmark clothes washer does not have this feature. 

Water Heater Fuel Type in Prototype 

Electric Gas 

Storage Capacity (V) (Gallons) 50 40 

Energy Factor (EF) 0.86 0.54 

Recovery Efficiency (RE) 0.98 0.76 

Burner Capacity 5.5 kW 36,000 Btu/hr 

Supply Temperature 120°F 

Fuel Type Same as Prototype 

Tank Location Same as Prototype 
14

Table 9. Domestic Hot Water Consumption by End Use 

End Use End-Use Water 

Temperature Water Usage 

Clothes Washer N/A 7.5 + 2.5 x Nbr gal/day (Hot Only) 

Dishwasher N/A 2.5 + 0.833 x Nbr gal/day (Hot Only) 

Shower and Bath 105°F 17.5 + 5.83 x Nbr gal/day (Hot + Cold) 

Sinks 105°F 12.5 + 4.16 x Nbr gal/day (Hot + Cold) 

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 6. Clothes washer hot water use profile 
15

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 7. Dishwasher hot water use profile 

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 8. Shower, bath, and sink hot water use profile 
16

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 9. Combined domestic hot water use profile 

The mains water temperature for a typical house varies significantly depending on the location and time 

of year. The following equation, based on TMY2 data for the location of the Prototype, shall be used to 

determine the daily mains water temperature for both the Benchmark and the Prototype: 

Equation 4: Tmains = (Tamb,avg + offset) + ratio * (∆Tamb,max / 2) * sin (0.986 * (day# - 15 - lag) - 90)

where 

Tmains = mains (supply) temperature to domestic hot water tank (oF) 

Tamb,avg = annual average ambient air temperature (oF) 

∆Tamb,max = maximum difference between monthly average ambient 

 temperatures (e.g., Tamb,avg,july – Tamb,avg,january) (oF) 

0.986 = degrees/day (360/365) 

day# = Julian day of the year (1-365) 

offset = 6°F 

ratio = 0.4 + 0.01 (Tamb,avg – 44) 

lag = 35 – 1.0 (Tamb,avg – 44). 

This equation is based on analysis by Christensen and Burch of NREL using data for multiple locations, 

as compiled by Abrams and Shedd (1996), Florida Solar Energy Center (Parker 2002), and Sandia 

National Laboratories (Kolb 2003). The offset, ratio, and lag factors were determined by fitting the 

available data. The climate-specific ratio and lag factors are consistent with water pipes being buried 

deeper in colder climates. 
17

In order for the constant terms in the ratio and lag factors to be representative of an average climate, the 

data fitting was done relative to a nominal Tamb,avg = 44oF. The lag is relative to ambient air temperature, 

and Tamb,minimum is assumed to occur in mid-January (day# = 15). The choices for these nominal values are 

not critical, because although different assumptions would change the constant terms in the ratio and lag

factors, the coefficients would also change, so the prediction of Tmains values would be unchanged. For 

models that use average monthly mains temperature, day# in Equation 4 shall be calculated using 

Equation 5. 

 Equation 5: day# = 30 * month# - 15 

 where month# = month of the year (1–12). 

An example using Equations 4 and 5 to determine the monthly mains temperature profile for Chicago, 

Illinois, is shown in Figure 10. 

Using TMY2 data for Chicago, IL

0

10

20

30

40

50

60

70

80

1 2 3 4 5 6 7 8 9 10 11 12

Month

Temperature (F) & Gallons/day

T ambient

T mains

DHW gal/day

BA - Monthly Mains Water Temperature and DHW Usage

Figure 10. Mains temperature profile for Chicago 
18

Air Infiltration and Ventilation 

The hourly natural air change rate for the Benchmark shall be calculated based on the Specific Leakage 

Area (SLA) determined using Equation 6: 

 Equation 6: SLA = ELA/CFA = 0.00057 

where ELA = effective leakage area (ft2

), defined as the amount of open area 

that would result in the same total air exchange as the actual 

leakage area of the house at a pressure of 4 Pa 

 CFA = conditioned floor area (ft2

). 

When specifying natural infiltration for a Benchmark with either a directly or indirectly conditioned 

basement, the SLA shall be adjusted to account for the in-ground portions of the walls of the conditioned 

basement. Equation 7 shall be used to make this adjustment: 

 Equation 7: SLAoverall = [(CFAbsmt* SLAbsmt) + (CFAa-g* SLAa-g)] / [CFAtotal] 

 

 where 

 SLA = ELA (ft2

) / CFA (ft2) 

 SLAa-g = SLAstd (where subscript “a-g” indicates above-grade or exposed) 

 SLAbsmt = SLAstd*(above-grade basement wall area)/(total basement wall area) 

 SLAstd = 0.00057. 

This can be calculated by zone, applying SLAbsmt to the basement zone and SLAstd to the above-grade 

zone of the Benchmark and treating the energy balances separately for each zone. It can also be done by 

applying SLAoverall to the combined spaces if the Benchmark is modeled as a single zone. 

Additional air exchange as a result of mechanical ventilation shall be calculated using Equation 8, based 

on a simple continuous exhaust fan designed in accordance with ASHRAE Standard 62.2, and added to 

the natural infiltration assuming negligible interactive effects. The fan energy use for the Benchmark 

shall be calculated using Equation 9. 

 Equation 8: Ventilation air exchange (cfm) = 0.01 x FFA + 7.5 x (Nbr +1) 

 where FFA = finished floor area (ft2

) 

 Nbr = number of bedrooms. 

 Equation 9: Ventilation fan energy (kWh/yr) = 0.03942 x FFA + 29.565 x (Nbr +1) , 

Note that finished floor area is used in these equations instead of conditioned floor area. We believe that 

finished floor area more accurately represents the area that occupants use in their daily activities (see also 

the treatment of lighting and plug loads). 

It is assumed that cross-ventilation is available to provide natural ventilation in the Benchmark under 

favorable weather conditions. 
19

Lighting Equipment and Usage 

The total annual hard-wired lighting use for the Benchmark is determined using Equations 10 through 12. 

These equations are derived from data for both single-family and multi-family housing documented in a 

lighting study conducted by Navigant for DOE (Navigant 2002). 

Equation 10: Interior lighting = 0.8*(FFA * 0.8 + 455) kWh/yr. 

Equation 11: Garage lighting = 100 kWh/yr. 

Equation 12: Exterior lighting = 250 kWh/yr. 

Annual hard-wired indoor lighting, in kilowatt-hours, represents approximately 80% of all indoor lighting 

and is expressed as a linear function of finished house area relative to a constant base value. Garage and 

exterior lighting are treated as constants. When combined with plug-in lighting (discussed in the next 

section), the total interior lighting calculated using this equation is in the middle range of residential 

lighting energy use found in other lighting references, as shown in Figure 11, including Huang and Gu 

(2002), the 1993 Residential Energy Consumption Survey (RECS) (DOE 1996), a Florida Solar Energy 

Center study (Parker et al. 2000), default lighting for Visual DOE software (Eley 2002), a lighting study 

conducted by Navigant for DOE (Navigant 2002), and two other studies in Grays Harbor, Washington 

(Manclark and Nelson 1992), and Southern California (SCE 1993). 

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 500 1000 1500 2000 2500 3000 3500 4000

House Size (ft2)

Annual Indoor Lighting (kWh)

Benchmark

Huang & Gu

FSEC

Visual DOE

RECS 93

Navigant

Grays Harbor

SCE

Figure 11. Comparison of Benchmark lighting equation to other references 
20

The Benchmark lighting budget is based on an assumption that 86% of the interior lighting comes from 

fixtures that contain incandescent lamps, and the remaining 14% is assumed to come from fixtures 

containing fluorescent lamps. This is consistent with the source data set from 161 homes monitored by 

Tacoma Public Utilities (TPU) for the Bonneville Power Administration, which was the basis for the 

Navigant study. Although the core data set used in this study is the most complete and comprehensive 

residential lighting data set that we have identified, it is nevertheless limited in terms of geographic 

location, number of homes, length of study, percent of fixtures monitored, and type of homes studied. 

The Navigant report includes an appendix providing information about the characteristics of the homes 

monitored in the TPU study. 

If a comprehensive lighting plan has not been developed for the Prototype house, and only fluorescent 

and incandescent lamps are installed, then a simplified approach may be used to estimate energy savings 

compared to the Benchmark using Equation 13. This equation is based on an assumption that the 

efficacies of incandescent and fluorescent light fixtures are the same in the Prototype as they were in the 

TPU study and that fluorescent lighting is distributed equally among hard-wired fixtures in all rooms. 

 Equation 13: Prototype hard-wired indoor lighting (kWh/yr) = LB*(1.12*FI + 0.279*FF) 

 where LB = indoor lighting for the Benchmark from Equation 10 (kWh/yr) 

 FI = fraction of hard-wired lamps that are incandescent 

 FF = fraction of hard-wired lamps that are fluorescent. 

The annual average normalized daily load shape for interior lighting use is shown in Figure 12, based on a 

draft LBNL report by Huang and Gu (2002). This load shape is also used for exterior and garage lighting. 

Monthly variations in load shape and lighting energy use as a result of changes in the length of days can 

be accounted for, as long as the variation is applied to all the simulation models and total annual energy 

use remains the same. 

Energy savings may be calculated on the basis of a number of usage variations, depending on the 

capability of the modeling tool. Variations include day types (weekday vs. weekend), occupancy types 

(day-use vs. non-day-use or “nuclear” vs. “yuppie”), season (summer vs. winter), and room types (living 

area vs. bedroom area). 

Individual normalized profiles can be “rolled up” to various levels of detail appropriate to the simulation 

model. An example of one detailed set of profiles developed by NREL is shown in Figure 13. Other 

profiles are included in spreadsheets available on the Building America Web site 

(http://www.eere.energy.gov/buildings/building_america/pa_resources.html). 
21

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

fraction of daily total

Figure 12. Interior lighting profile (built up from detailed profiles) 

Annual Average Lighting Profile

Day-Use, Living Areas, Weekdays, by Season

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

fraction of maximum

Ltg-DU-LR-WD-WI

Ltg-DU-LR-WD-SU

Ltg-DU-LR-WD-SF

Figure 13. Example of a detailed lighting profile (expressed as fraction of peak daily lighting 

energy) 

The lighting plans for the Prototype and Benchmark should be based on the same hours of operation 

unless the Prototype includes specific design measures that alter the operating time of the lighting system, 

such as occupancy sensors, dimming switches, or a building automation system. Average operating hours 

estimated in the Navigant study are generally a good starting point (Table 10), but there may be 

substantial differences between typical lighting designs found in the TPU sample and the lighting design 

developed in conjunction with the architecture of the Prototype. The analyst must ultimately apply good 

engineering judgment when specifying operating hours for the lighting system. 
22

Table 10. Average Lighting Operating Hours for Common Room Types in a Sample of 161 Homes 

in the Pacific Northwest (Source: Navigant 2002) 

Room Type Operation 

(Hours/day/room) Room Type Operation (Hours/day/room)

Bathroom 1.8 Kitchen 3.0 

Bedroom 1.1 Living Room 2.5 

Closet 1.1 Office 1.7 

Dining Room 2.5 Outdoor 2.1 

Family Room 1.8 Utility Room 2.0 

Garage 1.5 Other 0.8 

Hall 1.5 

Appliances and Other Plug Loads 

As with lighting, several characteristics must be defined for appliances and other plug loads: the amount 

of the load, the schedule of the load, the location of the load, the fraction of the load that becomes a 

sensible load, and the fraction of the load that becomes a latent load. Though the internal load may be 

treated as an aggregate, the energy consumption for each end use must be considered separately. A 

breakdown of annual energy consumption and associated internal loads for major appliances and other 

equipment is shown in Table 11. Not all of the energy consumed by appliances is converted into internal 

load; much of the waste heat is exhausted to the outside or released down the drain in the form of hot 

water. The appliance loads were derived by NREL from EnergyGuide labels, a Navigant analysis of 

typical models available on the market that meet current NAECA appliance standards, and several other 

studies. The daily loads rolled up at the whole-house level for a typical 1800-ft2

, three-bedroom house in 

Chicago are shown in Table 12. 

For a house of typical size (1000-3000 ft2

), the loads from the occupants and most appliances are assumed 

to be a function of the number of bedrooms. The exceptions are the refrigerator and cooking loads, which 

are assumed to be constant regardless of the number of bedrooms. The “Other Appliance & Plug Loads” 

end use is assumed to be primarily a function of finished floor area. A multiplier is applied if the 

prototype is located in one of the four most populated states as determined in the EIA Residential Energy 

Consumption Survey (RECS) (DOE 2001). Multipliers for these four states were estimated based on the 

final electric end-use regression equations developed for the 2001 RECS, substituting national average 

values for known housing characteristics and physical traits of the occupants (such as number of 

bedrooms, number of ceiling fans, and age of homeowner) and removing end-uses that are disaggregated 

in the Benchmark (such as lighting and clothes dryer). The resulting multipliers are listed in Table 13. 

The multiplier is 1.0 for all states not listed because insufficient information is available about the 

magnitude of plug loads in those states. 
23

The plug load equation brings the total internal sensible load (including heat gain from occupants) 

approximately in line with the equation used to calculate internal loads in the IECC (ICC 2003) and with 

the total energy consumption for single-family homes in the 2001 RECS. However, the internal load 

from appliances and lighting in the IECC equation is not a function of the number of bedrooms. 

Therefore, it is impossible to fully reconcile the Benchmark internal heat gain with that of the IECC for 

all combinations of floor area and number of bedrooms. However, the internal loads for the Benchmark 

and IECC are consistent for a typical 1800-ft2

, three-bedroom house. The constant internal sensible load 

value of 72,000 Btu/day specified in the HERS guidelines (RESNET 2002) is even less flexible than the 

equation in the IECC. Still, the HERS internal load is approximately the same as the sensible load 

calculated based on Table 11 (73,052 Btu/day) for a typical 1800-ft2

, three-bedroom house. Table 11 also 

results in a total latent load equal to approximately 20% of the total sensible load for a house of typical 

size, which is consistent with the HERS Guidelines. The IECC does not address latent load. 

Table 11. Annual Appliance and Equipment Loads for the Benchmark3

Appliance 

Electricity 

(kWh/yr) 

Natural Gas 

(therms/yr) 

Sensible 

Load 

Fraction 

Latent Load 

Fraction 

Refrigerator 669 1.00 0.00 

Clothes Washer (3 ft3

drum) 52.5 + 17.5 x Nbr 0.80 0.00 

Clothes Dryer 

(Electric) 418 + 139 x Nbr 0.15 0.05 

Clothes Dryer (Gas) 38 + 12.7 x Nbr 26.5 + 8.8 x Nbr

1.00 (Electric) 

0.10 (Gas) 

0.00 (Electic)

0.05 (Gas) 

Dishwasher (8 place 

settings) 103 + 34.3 x Nbr 0.60 0.15 

Range (Electric) 604 0.40 0.30 

Range (Gas) 45 0.30 0.20 

Plug-In Lighting 0.2*(FFA * 0.8 + 

455)] 1.00 0.00 

Other Appliance & 

Plug Loads 1.67 x FFA x FS 0.90 0.10 

 

3 End-use loads in this table include only energy used within the machine. Associated domestic hot water use is 

treated separately (see “Domestic Hot Water”). The Appliance spreadsheet on the Building America Web site 

(www.eere.energy.gov/buildings/building_america/benchmark_def.html) can assist with the calculation of this split 

for an energy-efficient clothes washer or dishwasher based on the EnergyGuide label. 
24

Table 12. Total Rolled-Up Appliance and Equipment Loads for the Benchmark 

(1800-ft2

, Three-bedroom Prototype, Chicago) 

House Type Electric 

kWh/yr 

Sensible 

Fraction

Latent 

Fraction

Gas 

therms/yr

Sensible 

Fraction 

Latent 

Fraction

All Electric 5804 0.75 0.10 

Electric with gas 

dryer 5045 0.78 0.10 53 0.10 0.05 

Electric with gas 

cooking 5200 0.72 0.07 45 0.30 0.20 

Gas dryer/cooking 4441 0.92 0.07 98 0.19 0.12 

Table 13. Plug Load Multipliers for Four Most Populated States (FS). 

State Multiplier (FS) 

New York 0.82 

California 0.77 

Florida 0.94 

Texas 1.11 

All other States and territories 1.00 

The hourly, normalized load shape for combined residential equipment use is shown in Figure 14 and is 

based on the ELCAP study of household electricity use in the Pacific Northwest (Pratt et al. 1989). In 

most situations this profile is adequate for simulating all electric and gas end-uses except space 

conditioning and hot water. However, because some individual end-use profiles are nearly constant (such 

as refrigerator and transformer loads) and some are highly dependent on time of day (such as the range 

and dishwasher), we have also developed a series of normalized hourly profiles for major appliances and 

plug loads, shown in Figures 15 through 20. Numerical values associated with these profiles can be 

found in the “Appliances and Domestic Hot Water” spreadsheet posted on the Building America web site 

(http://www.eere.energy.gov/buildings/building_america/pa_resources.html). The hourly profiles 

for machine energy usage in the clothes washer and dishwasher are identical to those provided earlier in 

the section on DHW (see Figures 6 and 7). The profile for plug-in lighting is the same as the profile for 

hard-wired lighting presented in Figure 12. 
25

All hourly end-use profiles were taken from the ELCAP study, except the profile for “Other Appliance 

and Plug Loads,” which was derived by subtracting the energy consumption profiles for the major 

appliances from the combined profile for all equipment, assuming an all-electric, 1800-ft2

, three-bedroom 

house in Memphis, Tennessee. Internal sensible and latent loads from appliances and plug loads shall be 

modeled using the same profile used for end-use consumption. Appliance loads may be modeled in either 

the living spaces or bedroom spaces, depending on their location in the Prototype. 

Large end uses in the Prototype that are not part of typical houses (such as swimming pools, Jacuzzis, and 

workshops) are not included in the models for either the Prototype or the Benchmark. The efficiency of 

these end uses should be addressed in a separate analysis. 

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Average Hourly Electricity (kWh/hr)

Figure 14. Total combined residential equipment profile (Pratt 1989) 
26

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 15. Refrigerator normalized energy use profile (Pratt 1989) 

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 16. Clothes washer normalized machine energy use profile (Pratt 1989) 
27

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 17. Clothes dryer normalized energy use profile (Pratt 1989) 

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 18. Dishwasher normalized energy use profile (Pratt 1989) 
28

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 19. Range/oven normalized energy use profile (Pratt 1989) 

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour of Day

Fraction of Total Daily Usage

Figure 20. Other appliance and plug load normalized energy use profile 
29

Site Generation 

A review of data from the Energy Information Administration (DOE 2001) shows that there is rarely any 

site electricity generation in a 1990s vintage house. This is a reflection of the low market penetration of 

site electricity systems. Therefore, all electricity is purchased from the local utility in the Benchmark. As 

costs for photovoltaic systems and other site electricity systems continue to decline, they are expected to 

begin to make a significant contribution toward meeting residential energy needs by the year 2020. 

Therefore, site electricity generation must be included in the whole-house energy performance analysis of 

the Prototype. 

Operating Conditions 

The following operating conditions and other assumptions shall apply to both the Prototype house and the 

Benchmark. The operating conditions are based on the cumulative experience of the authors through their 

work on Building America, HERS, Codes and Standards, and other residential energy efficiency 

programs. 

• Thermostat set points based on the optimum seasonal temperature for human comfort as defined 

in ASHRAE Standard 55-1992 (ASHRAE 1992). 

Set point for cooling: 76°F with no setup period 

Set point for heating: 71°F with no setback period 

• The natural ventilation schedule shall be set to reflect windows being opened occasionally. In 

situations in which there is a cooling load, the outdoor temperature is below the indoor 

temperature, and the windows are not already open, then the probability of the windows being 

opened shall be set at a constant 50%. The natural ventilation rate shall be 5 ACH unless each 

living area and bedroom provides at least two openings on different orientations and the net area 

of openings exceeds 12% of the floor area of the house (cross-ventilation), in which case a natural 

ventilation rate of 7 ACH shall be used. If there are local circumstances that would tend to 

discourage window operation (pollution, security, community standards, etc), then it is acceptable 

to use a lower probability than 50%, as long as the same natural ventilation schedule is applied to 

both the Benchmark and Prototype. 

 

• Interior shading multiplier = 0.7 during the cooling season and 0.85 during the heating season and 

during swing seasons when both cooling and heating occur. Specific guidelines for defining 

seasons are presented later in this section. 

 

• Internal loads from lighting, appliances, and other equipment were discussed in previous sections. 

These loads are not necessarily the same for the Prototype and the Benchmark; therefore, they are 

not considered operating conditions for the purposes of the Building America performance 

analysis. 

• Annual cycles for clothes washers, dryers, and dishwashers calculated using the NREL Appliance 

and DHW spreadsheet posted on the Building America website. 

• The occupancy schedule is defined with the same level of detail as other internal load profiles. 

For typical Building America houses, the number of occupants shall be assumed to be equal to 

the number of bedrooms. Sensible and latent gains shall be accounted for separately, and 

different loads shall be applied in different space types, as described in Table 14. The occupant 
30

heat gains are based on ASHRAE recommendations (ASHRAE 2001a). The average hourly 

occupancy profile is shown in Figure 21, and an example set of detailed hourly occupancy curves 

is shown in Figure 22. Detailed occupancy profiles based on different day and room types are 

available in spreadsheet format on the Building America Web site 

(http://www.eere.energy.gov/buildings/building_america/pa_resources.html). These profiles, 

which were developed by NREL, were based on the basic ASHRAE occupancy schedule 

combined with engineering judgment. 

Table 14. Peak Sensible and Latent Heat Gain from Occupants (ASHRAE 2001a) 

Living A rea S ens ible Gain: 230 B TU/person/hr

Bedroom A rea Sensible Gain: 210 B TU/person/hr

Living A rea Latent Gain: 190 B TU/person/hr

Bedroom A rea Latent Gain: 140 B TU/person/hr
31

Figure 21. Average hourly load profile from occupants for all day-types and family types (16.5 

hours/day/person total) 

Occupancy Profiles

by Day-Type and Space-Type

0.0

0.2

0.4

0.6

0.8

1.0

1

3

5

7

9

11

13

15

17

19

21

23

fraction of total people

Occ-LR-WD Occ-LR-WE

Occ-BR-WD Occ-BR-WE

Figure 22. Detailed hourly load profiles resulting from occupants being in different parts of the 

house on weekdays (WD) and weekends (WE) 

Occupancy Profile

daily average - whole house

0.0

0.2

0.4

0.6

0.8

1.0

1

3

5

7

9

11

13

15

17

19

21

23

fraction of total people
32

• The internal mass of furniture and contents shall be equal to 8 lbs/ft2 of conditioned floor space. 

For solar distribution purposes, lightweight furniture covering 40% of the floor area shall be 

assumed. 

 

• Weather data shall be based on typical meteorological year (TMY2) data from 1961 to 19904 or 

equivalent data for the nearest weather station. 

 

• Heating and cooling shall only occur during certain months of the year in accordance with the 

guidelines presented below. Alternate operating profiles may be acceptable with sufficient 

justification. The heating and cooling seasons shall be determined on the basis of the monthly 

average temperatures (MAT) and the 99% (annual, not seasonal) winter and summer design 

temperatures (WDT and SDT, respectively) based on TMY2 data or ASHRAE Fundamentals 

2001 for the nearest location, in accordance with the following procedures: 

Step 1. MAT Basis 

(I) The heating system shall be enabled for a month in which the MAT is less 

than 71.5°F. 

(II) The cooling system shall be enabled for a month in which the MAT is 

greater than 66°F. 

Step 2. WDT and SDT 

(I) The heating system shall be enabled in December and January if the WDT 

is less than or equal to 59°F, regardless of the outcome in Step 1 above. 

(II) The cooling system shall be enabled in July and August regardless of the 

outcome in Step 1 above. 

Step 3. Swing Season Adjustment 

(I) If, based on Steps 1 and 2 above, there are two consecutive months in 

which the heating system is enabled the first month and the cooling system 

is enabled the following month, or vice versa, then both the heating system 

and the cooling system shall be enabled for both of these months.

Reporting Energy Use and Energy Savings 

Reporting energy use and energy savings in a consistent format is an important component of Building 

America analysis. The following tables shall be supplied with the analysis report for every Building 

America Prototype. 

Table 15 shows an example of a site energy consumption report for a hypothetical Prototype in Virginia, 

along with all relevant base cases. Similar information based on source energy is presented in Table 16, 

along with percent energy savings for each end use. End uses are described in more detail in Table 17. 

 

4 Analytic Studies Division, National Renewable Energy Laboratory 

(http://rredc.nrel.gov/solar/old_data/nsrdb/tmy2/).
33

The “Percent of End Use” columns in Table 16 show the Prototype energy use for each end use as a 

fraction of the appropriate base case. The “Percent of Total” columns show the contribution of each end 

use toward an overall energy reduction goal. Note that site generation for the Benchmark is always zero. 

Source energy is determined using Equation 14. 

Equation 14: Source MBtu = kWh • 3.412 • Me /1000 + therms • Mg / 10 

 where Me = 3.16 = site-to-source multiplier for electricity (DOE 2002b) 

 Mg = 1.02 = site-to-source multiplier for natural gas (DOE 1995). 

Table 15. Example Summary of Site Energy Consumption by End Use 

Using Building America Research Benchmark 

Annual Site Energy 

 BA Benchmark Region Standard Builder Standard BA Prototype 

End Use (kWh) (therms) (kWh) (therms) (kWh) (therms) (kWh) (therms)

Space Heating 11225 0 11286 0 11286 0 4397 0 

Space Cooling 2732 0 2432 0 2432 0 902 0 

DHW 4837 0 4838 0 4838 0 1351 0 

Lighting 3110 3110 3110 1204 

Appliances + Plug 7646 0 7646 0 7646 0 7436 0 

OA Ventilation 400 400 400 400 

Total Usage 29950 0 29712 0 29712 0 15690 0 

Site Generation 0 0 0 0 0 0 7402 0 

Net Energy Use 29950 0 29712 0 29712 0 8289 0 

Table 16. Example Summary of Source Energy Consumption by End Use 

Using Building America Research Benchmark 

 Source Energy Savings 

Estimated Annual Source Energy Percent of End-Use Percent of Total 

 Benchmark Region Builder Proto BA Reg Bldr BA Reg Bldr 

End Use (MBtu/yr) (MBtu/yr) (MBtu/yr) (MBtu/yr) Base Base Base Base Base Base

Space Heating 115 116 116 45 61% 61% 61% 23% 23% 23% 

Space Cooling 28 25 25 9 67% 63% 63% 6% 5% 5% 

DHW 50 50 50 14 72% 72% 72% 12% 12% 12% 

Lighting 32 32 32 12 61% 61% 61% 6% 6% 6% 

Appliances + Plug 78 78 78 76 3% 3% 3% 1% 1% 1% 

OA Ventilation 4 4 4 4 0% 0% 0% 0% 0% 0% 

Total Usage 307 304 304 161 48% 47% 47% 48% 47% 47% 

Site Generation 0 0 0 -76 25% 25% 25% 

Net Energy Use 307 304 304 85 72% 72% 72% 72% 72% 72% 
34

Table 17. End-Use Categories 

End Use Potential Electric Usage Potential Gas Usage 

Space Heating Supply fan during space heating, 

HP, HP supplemental heat, water 

boiler heating elements, water 

boiler circulation pump, electric 

resistance heating, HP crankcase 

heat, heating system auxiliary 

Gas furnace, gas boiler, gas backup HP supplemental heat, gas 

ignition stand-by 

Space Cooling Central split-system A/C, 

packaged A/C (window or throughthe-wall), supply fan energy during 

space cooling, A/C crankcase 

heat, cooling system auxiliary 

Gas absorption chiller (rare) 

DHW Electric hot water heater, HP water 

heater, hot water circulation 

pumps 

Gas hot water heater 

Lighting Indoor lighting, outdoor lighting None 

Equipment Refrigerator, electric clothes dryer, 

gas clothes dryer (motor), cooking, 

miscellaneous 

Cooking, gas clothes dryer 

OA Ventilation Ventilation fans, supply air fan 

during ventilation mode 

None 

Site Generation Photovoltaic electric generation None 

Table 18 reports energy savings for individual energy efficiency measures applied to the Prototype, in 

terms of source energy and energy cost. “Source Energy Savings %” is determined by comparing the 

source energy for each measure increment to the source energy for the Benchmark (i.e., the first row). In 

this column, the incremental savings for each measure are added to the savings for all the previous 

measures. The final row of the column is the overall energy savings achieved for the Prototype house. 

When available, actual energy tariffs for the Prototype house shall be used to determine whole-building 

energy costs. Energy cost and measure savings are compared with the Builder Standard Practice 

(representing a real design or set of practices that is currently being used by the builder) rather than with 

the Benchmark. This provides an evaluation of the improvements in the performance of the Prototype 

compared with that of homes currently being sold by the builder partner. 

Reporting of peak hourly energy consumption is also encouraged for every Prototype. Peak energy is 

based on the hour with the greatest gas or electric energy consumption during the course of one year, as 

determined by the hourly simulation. 
35

 

Table 18. Example Measure Savings Report5 Using 

Building America Research Benchmark 

 National Average Builder Standard (Local Costs) 

Site Energy Est. Source Energy Energy Cost Energy Cost Measure Package 

Increment (kWh) (therms) (MBtu) 

Savings 

(%) ($/yr) Savings (%) ($/yr) 

Savings 

(%) Value ($/yr)

Savings 

($/yr) 

Bldg America 

Benchmark 29950 0 306.9 $ 2,995 $ 2,950 

Regional Std 

Practice 29712 0 304.4 1% $ 2,971 1% $ 2,927 

Builder Std 

Practice (BSP) 29712 0 304.4 1% $ 2,971 1% $ 2,927 

BSP + 

 improved walls 27779 0 284.6 7% $ 2,778 7% $ 2,736 7% $ 190.4 $ 190 

BSP ++ 

 Low-E Windows 25810 0 264.5 14% $ 2,581 14% $ 2,542 13% $ 193.9 $ 384 

BSP ++ 

 Smaller A/C (5 -

> 4 tons) 25420 0 260.5 15% $ 2,542 15% $ 2,504 14% $ 38.4 $ 423 

BSP ++ 

 Inc. Bsmt Wall 

Insulation 25170 0 257.9 16% $ 2,517 16% $ 2,479 15% $ 24.6 $ 447 

BSP ++ 

Ground Source 

HP (+DHW) 19331 0 198.1 35% $ 1,933 35% $ 1,904 35% $ 575.1 $ 1,023 

BSP ++ 

 Solar DHW 17718 0 181.5 41% $ 1,772 41% $ 1,745 40% $ 158.9 $ 1,181 

BSP ++ 

 Lighting, Appl. & 

Plug 15690 0 160.8 48% $ 1,569 48% $ 1,545 47% $ 199.8 $ 1,381 

Site Generation 

BSP ++ 

 PV 8288 0 84.9 72% $ 829 $ 816 72% $ 729.0 $ 2,110 

 

5 Calculated using national average electric cost = $0.10/kWh and national average gas cost = $0.50/therm. 
36

References 

Abrams, D.W., Shedd, A.C. 1996. “Effect of Seasonal Changes in Use Patterns and Cold Inlet Water 

Temperature on Water Heating Load.” ASHRAE Transactions, AT-96-18-3. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). 1992. 

“Thermal Environmental Conditions for Human Occupancy,” ASHRAE Standard 55-1992, Atlanta, 

GA. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). 1993. A 

Method of Determining Air Change Rates in Detached Dwellings, ASHRAE Standard 136-1993, 

Atlanta, GA. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). 1999. HVAC 

Applications Handbook. Atlanta, GA: ASHRAE. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). 2001a. 

Fundamentals Handbook. Atlanta, GA: ASHRAE. 

American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). 2001b. 

“Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal 

Distribution Systems,” Proposed ASHRAE Standard 152P, Atlanta, GA. 

Becker, B.R., Stogsdill, K.E. 1990. “Development of Hot Water Use Data Base.” ASHRAE Transactions, 

Vol. 96, Part 2, pp. 422-427. 

Burch, J., Salasovich, J. 2002. “Flow Rates and Draw Variability in Solar Domestic Hot Water Usage.” 

Proceedings of the Solar 2002 Conference Including Proceedings of the 31st ASES Annual 

Conference and Proceedings of the 27th National Passive Solar Conference, 15-20 June 2002, Reno, 

Nevada. Boulder, CO: American Solar Energy Society, Inc. (ASES); pp. 287-292; NREL Report No. 

CP-550-31779. 

Burch, J., Erickson, P. 2004 (Draft). “Deriving Inputs for Storage Tank Water Heater Models from Rating 

Data.” Conference paper. Golden, CO: National Renewable Energy Laboratory. 

California Energy Commission. 2002. California Building Energy Efficiency Standards, Part 1, Measure 

Analysis and Life Cycle Cost, CEC, Sacramento, CA. 

Christensen, C., Barker, G., Thornton, J. 2000. Parametric Study of Thermal Performance of Integral 

Collector Storage Solar Water Heaters. NREL Report No. CP-550-28043. Conference paper. 

Golden, CO: National Renewable Energy Laboratory. 

Eley Associates. 2002. Visual DOE Version 3.1. San Francisco, CA: Eley Associates. 

Huang, J., Gu, L. 2002 (Draft). Prototypical Residential Buildings to Represent the US Housing Stock.

Berkeley, CA: Lawrence Berkeley National Laboratory. 

Hendron, R., Anderson, R., Judkoff, R., Christensen, C., Eastment, M., Norton, P., Reeves, P., Hancock, 

E. 2004. Building America Performance Analysis Procedures, Rev. 1. NREL/TP-550-35567, Golden, 

CO: National Renewable Energy Laboratory. 

International Code Council (ICC). 2003. International Energy Conservation Code 2003. Falls Church, 

VA. 

Kolb, G. October 2003. Private communication. Albuquerque, NM: Sandia National Laboratories. 

Manclark, B., Nelson, M. 1992. The Grays Harbor PUD Compact Fluorescent Maximization Study.

Grays Harbor, WA: Grays Harbor Public Utility District. 
37

National Renewable Energy Laboratory (NREL). 1995. Solar Radiation Data Manual for Buildings. 

NREL/TP-463-7904. Golden, CO: National Renewable Energy Laboratory. 

Navigant Consulting. 2002. U.S. Lighting Market Characterization: Volume 1: National Lighting 

Inventory and Energy Consumption Estimate. Washington, D.C.: Navigant Consulting. 

Parker, D. 2002. Research Highlights from a Large Scale Residential Monitoring Study in a Hot Climate

(and personal communication). FSEC-PF369-02. Cocoa, FL: Florida Solar Energy Center. 

Parker, D., et al. September 2000. FPC Residential Monitoring Project: Assessment of Direct Load 

Control and Analysis of Winter Performance. Prepared for the Florida Power Corporation, FSEC-CR1112-99. Cocoa, FL. 

Pratt, R., Conner, C., Richman, E., Ritland, K., Sandusky, W., Taylor, M. 1989. "Description of Electric 

Energy Use in Single-Family Residences in the Pacific Northwest – End-Use Load and Consumer 

Assessment Program (ELCAP),” DOE/BP-13795-21, Richland, WA: Pacific Northwest National 

Laboratory. 

Residential Energy Services Network (RESNET). 2002. “Mortgage Industry National Home Energy 

Rating Systems Accreditation Standards.” Chapter 3, pp. 29-54. San Diego, CA: RESNET. 

Southern California Edison (SCE). 1993. Final Report: Residential Lighting Study (Inventory Results).

Rosemead, CA. 

U.S. Department of Energy (DOE). December 1995. Measuring Energy Efficiency in the United States 

Economy: A Beginning. Chapter 7. Available online at 

http://www.eia.doe.gov/emeu/efficiency/ee_report_html.htm (accessed May 2004). Washington, D.C. 

U.S. Department of Energy (DOE). 1996. Residential Lighting Use and Potential Savings. DOE/EIA0555(96)/2. Washington, D.C. 

U.S. Department of Energy (DOE). November 1999. “1997 Residential Energy Consumption Survey”. 

Available online at http://www.eia.doe.gov/emeu/recs/1997. Washington, D.C. 

U.S. Department of Energy (DOE). 2001. Annual Energy Outlook 2002. Washington, D.C. 

U.S. Department of Energy (DOE). May 2002a. “Residential Energy Efficiency and Appliance 

Standards.” http://www.eere.energy.gov/consumerinfo/refbriefs/ee8.html (accessed May 2004). 

Washington, D.C. 

U.S. Department of Energy (DOE). July 2002b. “2002 Buildings Energy Databook” online at 

http://btscoredatabook.eren.doe.gov/; see the 2003 databook at http://btscoredatabook.eren.doe.gov/

(accessed May 2004). Washington, D.C. 

U.S. Department of Housing and Urban Development (HUD). 1982. “Minimum Property Standards for 

One- and Two-Family Living Units.” No. 4900.1-1982. Washington, D.C. 

Wassmer, M. 2003. “A Component-Based Model for Residential Air Conditioner and Heat Pump 

Energy Calculations.” Masters Thesis, University of Colorado at Boulder.
F1147-E(05/2004) 

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, 

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this 

collection of information, including suggestions for reducing the burden, to Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents 

should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a 

currently valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

February 2005 

2. REPORT TYPE

Technical Report 

3. DATES COVERED (From - To)

 

5a. CONTRACT NUMBER

DE-AC36-99-GO10337 

5b. GRANT NUMBER

4. TITLE AND SUBTITLE

Building America Research Benchmark Definition, Updated 

December 29, 2004 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-550-37529 

5e. TASK NUMBER

BET5.8004 

6. AUTHOR(S)

R. Hendron 

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401-3393 

8. PERFORMING ORGANIZATION 

REPORT NUMBER

NREL/TP-550-37529 

10. SPONSOR/MONITOR'S ACRONYM(S)

NREL 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

11. SPONSORING/MONITORING 

AGENCY REPORT NUMBER

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

To track progress toward aggressive multi-year whole-house energy savings goals of 40-70% and onsite power 

production of up to 30%, the U.S. Department of Energy (DOE) Residential Buildings Program and the National 

Renewable Energy Laboratory (NREL) developed the Building America Research Benchmark in consultation with the 

Building America industry teams. The Benchmark is generally consistent with mid-1990s standard practice, as 

reflected in the Home Energy Rating System (HERS) Technical Guidelines (RESNET 2002), with additional 

definitions that allow the analyst to evaluate all residential end-uses, an extension of the traditional HERS rating 

approach that focuses on space conditioning and hot water. A series of user profiles, intended to represent the 

behavior of a “standard” set of occupants, was created for use in conjunction with the Benchmark. 

15. SUBJECT TERMS

Building America; U.S. Department of Energy; residential homes; research benchmark; whole-house energy savings; 

HERS guidelines 

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON 

a. REPORT 

Unclassified 

b. ABSTRACT 

Unclassified

c. THIS PAGE 

Unclassified

17. LIMITATION 

OF ABSTRACT

UL 

18. NUMBER 

OF PAGES 

19b. TELEPONE NUMBER (Include area code)

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18
Bringing you a prosperous future where energy is clean, abundant, reliable, and affordable

A Strong Energy Portfolio 

for a Strong America

Energy effi ciency and clean, renewable 

energy will mean a stronger economy, 

a cleaner environment, and greater 

energy independence for America. 

Working with a wide array of state, 

community, industry, and university 

partners, the U.S. Department of 

Energy’s Offi ce of Energy Effi ciency 

and Renewable Energy invests in a 

diverse portfolio of energy technologies.

Research and Development 

of Buildings

Our nation’s buildings consume more 

energy than any other sector of the 

U.S. economy, including transportation 

and industry. Fortunately, the opportunities to reduce building energy use—

and the associated environmental 

impacts—are signifi cant.

DOE’s Building Technologies Program 

works to improve the energy effi ciency 

of our nation’s buildings through innovative new technologies and better 

building practices. The program

focuses on two key areas:

• Emerging Technologies 

Research and development of the 

next generation of energy-effi cient 

components, materials, and 

equipment

• Technology Integration

Integration of new technologies 

with innovative building methods 

to optimize building performance 

and savings

For more information contact:

EERE Information Center

1-877-EERE-INF (1-877-337-3463)

www.eere.energy.gov

An electronic copy of this factsheet is 

available on the Building America Web 

site at www.buildingamerica.gov

U.S. Department of Energy

Energy Effi ciency

and Renewable Energy

Building America Program

George S. James • New Construction • 202-586-9472 • fax: 202-586-8134 • e-mail: George.James@ee.doe.gov

Terry Logee • Existing Homes • 202-586-1689 • fax: 202-586-4617 • e-mail: terry.logee@ee.doe.gov

Lew Pratsch • Integrated Onsite Power • 202-586-1512 • fax: 202-586-8185 • e-mail: Lew.Pratsch@hq.doe.gov

Building America Program • Offi ce of Building Technologies, EE-2J • U.S. Department of Energy • 1000 Independence Avenue, S.W. • 

Washington, D.C. 20585-0121 • www.buildingamerica.gov

Building Industry Research Alliance (BIRA)

Robert Hammon • ConSol • 7407 Tam O’Shanter Drive #200 • Stockton, CA 95210-3370 • 209-473-5000 • fax: 209-474-0817 • 

e-mail: Rob@consol.ws • www.bira.ws

Building Science Consortium (BSC)

Betsy Pettit • Building Science Consortium (BSC) • 70 Main Street • Westford, MA 01886 • 978-589-5100 • fax: 978-589-5103 • 

e-mail: Betsy@buildingscience.com • www.buildingscience.com

Consortium for Advanced Residential Buildings (CARB)

Steven Winter • Steven Winter Associates, Inc. • 50 Washington Street • Norwalk, CT 06854 • 203-857-0200 • fax: 203-852-0741 • 

e-mail: swinter@swinter.com • www.carb-swa.com

Davis Energy Group

David Springer • Davis Energy Group • 123 C Street • Davis, CA 95616 • 530-753-1100 • fax: 530-753-4125 •

e-mail: springer@davisenergy.com • deg@davisenergy.com • www.davisenergy.com/index.html

IBACOS Consortium

Brad Oberg • IBACOS Consortium • 2214 Liberty Avenue • Pittsburgh, PA 15222 • 412-765-3664 • fax: 412-765-3738 •

e-mail: boberg@ibacos.com • www.ibacos.com

Industrialized Housing Partnership (IHP)

Subrato Chandra • Florida Solar Energy Center • 1679 Clearlake Road • Cocoa, FL 32922 • 321-638-1412 • fax: 321-638-1439 • 

e-mail: subrato@fsec.ucf.edu • www.baihp.org

National Association of Home Builders (NAHB) Research Center

Tom Kenney • National Association of Home Builders (NAHB) Research Center • 400 Prince George’s Boulevard • 

Upper Marlboro, MD 20774 • 301-430-6246 • fax: 301-430-6180 • toll-free: 800-638-8556 • www.nahbrc.org/ 

National Renewable Energy Laboratory

Ren Anderson • 1617 Cole Boulevard, MS-2722 • Golden, CO 80401 • 303-384-7433 • fax: 303-384-7540 • 

e-mail: ren_anderson@nrel.gov • www.nrel.gov

Tim Merrigan • 1617 Cole Boulevard, MS-2722 • Golden, CO 80401 • 303-384-7349 • fax: 303-384-7540 • 

e-mail: tim_merrigan@nrel.gov • www.nrel.gov

Oak Ridge National Laboratory

Pat M. Love • P.O. Box 2008 • One Bethel Valley Road • Oak Ridge, TN 37831 • 865-574-4346 • fax: 865-574-9331 • 

e-mail: lovepm@ornl.gov • www.ornl.gov

Produced for the U.S. Department of Energy (DOE) by the National Renewable Energy Laboratory, a DOE national laboratory.

February 2005 • NREL/TP-550-37529

Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste.

Visit our Web sites at:

www.buildingamerica.gov www.energystar.gov