NIST Technical Note 1765

Prototype Residential Building 

Designs for Energy and 

Sustainability Assessment

Joshua Kneifel

http://dx.doi.org/10.6028/NIST.TN.1765

NIST Technical Note 1765 

Prototype Residential Building 

Designs for Energy and 

Sustainability Assessment

Joshua Kneifel 

Applied Economics Office 

Engineering Laboratory 

http://dx.doi.org/10.6028/NIST.TN.1765

October 2012

U.S. Department of Commerce 

Rebecca Blank, Acting Secretary

National Institute of Standards and Technology 

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director 
Certain commercial entities, equipment, or materials may be identified in this

document in order to describe an experimental procedure or concept adequately.

Such identification is not intended to imply recommendation or endorsement by the

National Institute of Standards and Technology, nor is it intended to imply that the

entities, materials, or equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Technical Note 1765 

Natl. Inst. Stand. Technol. Tech. Note 1765, 45 pages (October 2012) 

http://dx.doi.org/10.6028/NIST.TN.1765

CODEN: NTNOEF
i

Abstract

Residential building energy efficiency is becoming increasingly important in U.S. energy 

policy. Analyzing the effectiveness of potential energy efficiency improvements in the 

residential sector involves running whole building energy simulations for alternative 

building designs. Such analysis requires detailed building design characteristics including 

climate, fuel type, energy technologies, and design improvements. For broad studies of 

the U.S. residential sector, prototypical designs representing “typical” residential 

buildings are necessary to provide the basis for this detailed analysis.

This report defines two prototype detached residential house designs based on the 2009 

International Energy Conservation Code (IECC). These prototypes can be used as 

baselines from which to analyze homes built to older IECC codes as well as to estimate 

the energy savings and sustainability impacts from increasing residential building energy 

efficiency beyond current state energy codes. These prototypes can also be used as a 

framework for developing additional prototype designs.

Keywords

Building economics; life-cycle costing; energy efficiency; residential building; prototype 

building designs; sustainability assessment
ii
iii

Preface

This study was conducted by the Applied Economics Office (AEO) in the Engineering 

Laboratory (EL) at the National Institute of Standards and Technology (NIST). The study 

is designed to document the assumptions and approaches implemented in creating two

“prototypical” residential building designs to use as the basis for energy, life-cycle cost, 

and sustainability estimates for new and existing residential buildings. This document 

supersedes NIST TN 1688 for defining residential prototype designs. The intended 

audience is researchers in the residential building sector concerned with energy efficiency 

and sustainability.

Disclaimer

Certain trade names and company products are mentioned in the text in order to 

adequately specify the technical procedures and equipment used. In no case does such 

identification imply recommendation or endorsement by the National Institute of 

Standards and Technology, nor does it imply that the products are necessarily the best 

available for the purpose.

The policy of the National Institute of Standards and Technology is to use metric units in 

all of its published materials. Because this report is intended for the U.S. construction 

industry that uses U.S. customary units, it is more practical and less confusing to include 

U.S. customary units as well as metric units. Measurement values in this report are 

therefore stated in metric units first, followed by the corresponding values in U.S. 

customary units within parentheses.
iv
v

Acknowledgements

The author wishes to thank all those who contributed ideas and suggestions for this 

report. They include Ms. Barbara Lippiatt and Dr. Robert Chapman of EL’s Applied 

Economics Office, Dr. William Healy of EL’s Energy and Environment Division, Dr. 

Nicos S. Martys of EL’s Materials and Structural Systems Division, Philip Kerrigan of 

Building Science Corporation, and S. Craig Drumheller and Joseph Wiehagen of the 

National Association of Home Builders (NAHB) Research Center.

Author Information

Joshua D. Kneifel

Economist

National Institute of Standards and Technology

100 Bureau Drive, Mailstop 8603

Gaithersburg, MD 20899-8603

Tel.: 301-975-6857

Email: joshua.kneifel@nist.gov
vi
vii

Contents

Abstract............................................................................................................................... i

Preface...............................................................................................................................iii

Acknowledgements ........................................................................................................... v

Author Information .......................................................................................................... v

List of Acronyms............................................................................................................ xiii

1 Introduction............................................................................................................... 1

1.1 Background .......................................................................................................... 1

1.2 Purpose................................................................................................................. 1

1.3 Literature Review................................................................................................. 1

1.4 Approach .............................................................................................................. 2

2 One-Story Building Design Specification................................................................ 5

2.1 Building Envelope................................................................................................ 5

2.1.1 General Assumptions.................................................................................. 5

2.1.2 Climate Zone-Specific Assumptions.......................................................... 8

2.2 Heating, Ventilating, and Air Conditioning Equipment .................................... 10

2.3 Operating Conditions......................................................................................... 10

2.4 Outdoor Air Ventilation and Infiltration ............................................................ 10

2.5 Domestic Hot Water........................................................................................... 11

2.6 Lighting .............................................................................................................. 14

2.7 Appliances and Miscellaneous Electrical Loads................................................ 16

2.8 Internal Mass...................................................................................................... 17

2.9 Occupancy.......................................................................................................... 18

2.10Internal Heat Gains............................................................................................. 18

3 Two-Story Building Design Specification............................................................. 21

3.1 Building Envelope.............................................................................................. 21

3.1.1 General Assumptions................................................................................ 21

3.1.2 Climate Zone-Specific Assumptions........................................................ 24

3.2 Heating, Ventilating, and Air Conditioning Equipment .................................... 26

3.3 Operating Conditions......................................................................................... 26

3.4 Air Infiltration and Mechanical Ventilation....................................................... 26

3.5 Domestic Hot Water........................................................................................... 27

3.6 Lighting .............................................................................................................. 30

3.7 Appliances and Miscellaneous Electrical Loads................................................ 32

3.8 Internal Mass...................................................................................................... 33

3.9 Occupancy.......................................................................................................... 34

3.10Internal Heat Gains............................................................................................. 34

4 Recommendations for Future Research ............................................................... 37

References........................................................................................................................ 39

A Appendix.................................................................................................................. 41
viii
ix

List of Figures

Figure 2-1 Building material layers for exterior wall ........................................................ 6

Figure 2-2 Building material layers for ceiling.................................................................. 7

Figure 2-3 Building material layers for roof...................................................................... 7

Figure 2-4 Building material layers for slab-on-grade foundation .................................... 8

Figure 2-5 Domestic Hot Water Load Profiles as a Proportion of Peak Flow Rate, By 

Hour of the Day ................................................................................................................ 13

Figure 2-6 Electrical Equipment Load Profiles as a Proportion of Peak Wattage, By Hour 

of the Day.......................................................................................................................... 17

Figure 3-1 Building material layers for exterior wall ...................................................... 22

Figure 3-2 Building material layers for ceiling................................................................ 23

Figure 3-3 Building material layers for roof.................................................................... 23

Figure 3-4 Building material layers for slab-on-grade foundation .................................. 24

Figure 3-5 Domestic Hot Water Load Profiles as a Proportion of Peak Flow Rate, By 

Hour of the Day ................................................................................................................ 29

Figure 3-6 Electrical Equipment Load Profiles as a Proportion of Peak Wattage, By Hour 

of the Day.......................................................................................................................... 33

Figure A-1 ASHRAE Climate Zones by County............................................................. 41

Figure A-2 Conditioned Floor Area of New 1-Story Single-Family Housing ................ 42

Figure A-3 Conditioned Floor Area of New 2-Story Single-Family Housing ................ 43

Figure A-4 Conditioned Floor Area of New 1-Story Single-Family Housing by Number 

of Bedrooms...................................................................................................................... 44

Figure A-5 Conditioned Floor Area of New 2-Story Single-Family Housing by Number 

of Bedrooms...................................................................................................................... 45
x
xi

List of Tables

Table 2-1 Material Parameter Calculation Approach ........................................................ 5

Table 2-2 2009 IECC energy code requirements for exterior envelope ............................ 9

Table 2-3 Hot Water Consumption.................................................................................. 12

Table 2-4 Domestic Hot Water Daily Internal Heat Gains.............................................. 14

Table 2-5 Annual Lighting Electricity Consumption ...................................................... 15

Table 2-6 Lighting Load Profile as Proportion of Peak Wattage in Use, by Hour of the 

Day.................................................................................................................................... 15

Table 2-7 Appliance and MEL Electricity Consumption ................................................ 16

Table 2-8 Occupancy Load Profile as a Proportion of Maximum Occupancy, and Total 

Occupants, By Hour of the Day........................................................................................ 18

Table 2-9 Daily Heat Gain Comparison-Reference and Prototype Designs.................... 19

Table 3-1 Material Parameter Calculation Approach ...................................................... 21

Table 3-2 2009 IECC energy code requirements for exterior envelope .......................... 25

Table 3-3 Hot Water Consumption.................................................................................. 28

Table 3-4 Domestic Hot Water Internal Heat Gains........................................................ 30

Table 3-5 Annual Lighting Electricity Consumption ...................................................... 31

Table 3-6 Lighting Load Profiles as a Proportion of Peak Wattage in Use, By Hour of the 

Day.................................................................................................................................... 31

Table 3-7 Appliance and MEL Electricity Consumption ................................................ 32

Table 3-8 Occupancy Load Profile as a Proportion of Maximum Occupancy, and Total 

Occupants, By Hour of the Day........................................................................................ 34

Table 3-9 Heat Gain Comparison-Reference and Prototype Designs ............................. 35

Table 4-1 Additional Prototype Sizes.............................................................................. 37
xii
xiii

List of Acronyms

Acronym Definition

ACH Air Changes Per Hour

AEO Applied Economics Office

AFUE Annual Fuel Utilization Efficiency

AHS American Housing Survey

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

BA Building America

CBECS Commercial Building Energy Consumption Survey

CFA Conditioned Floor Area

CFL Compact Fluorescent Lighting

CFM Cubic Feet Per Minute

DOE Department of Energy

E+ EnergyPlus

EIA Energy Information Administration

EL Engineering Laboaratory

ELA Effective Leakage Area

EPA Environmental Protection Agency

GWB Gypsum Wall Board

HVAC Heating, Ventilating, and Air Conditioning

IECC International Energy Conservation Code

LBL Lawrence Berkeley Laboratory

MEL Miscellanous Electric Load

NBR number of bedrooms

NAHB National Association of Home Builders

NIST National Institute of Standards and Technology

NREL National Renewable Energy Laboratory

OC On Center

PNNL Pacific Northwest National Laboratory

RECS Residential Energy Consumption Survey

SEER Seasonal Energy Efficiency Ratio

SHGC Solar Heat Gain Coefficient

SLA Specific Leakage Area
xiv

Acronym Definition

VT Visible Transmittance

XPS Extruded Polystyrene
1

1 Introduction

1.1 Background

Previous research on residential building energy efficiency has created energy modeling 

parameters for predicting energy use for both new and existing residential buildings. 

These studies specify a majority of the parameters required to create a residential 

building energy simulation model, which are useful when the building design is known. 

However, prototype residential building designs that represent “typical” residential 

buildings are required to consistently analyze and compare energy efficiency 

improvements across the U.S. building stock.

1.2 Purpose

The purpose of this report is twofold. First, it develops and documents prototype 

residential building designs. These prototype designs provide a consistent basis for 

running building energy simulations across the U.S. residential building stock for 

different climate zones and varying levels of energy efficiency.1 Second, this report can 

be used as a basis for adding more prototype building designs or for developing more 

detailed designs of the prototypes reported here.

1.3 Literature Review

Previous research on prototype building designs has focused on commercial buildings. 

The National Renewable Energy Laboratory (NREL) has documented 16 commercial 

prototypical buildings for each of 16 U.S. climate zones.

2 These 256 reference

commercial buildings are based on the Commercial Building Energy Consumption 

Survey (CBECS) database and the American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) 90.1 Standard, and represent greater than 70 % of the 

U.S. building stock. These prototypes have become the basis for significant research on

energy efficiency measures in commercial buildings.

Two reports from the Building America (BA) program of the Department of Energy 

(DOE) Building Technologies Program -- Hendron and Engebrecht (2010) and Hendron 

(2006) -- document the assumptions for energy efficiency performance comparison for 

new and existing residential buildings, respectively. These reports define total loads and 

load profiles for energy and water usage within a home based on the number of 

bedrooms, bathrooms, and square footage. Since the focus of this study is on new 

 1 This document supersedes NIST TN 1688 for defining residential prototype designs. 2 Field, Deru, and Studer (2010)
2

residential buildings, Hendron and Engebrecht (2010) will be a primary source of 

information for the prototype designs.

Persily et al. (2007) define a suite of over 200 homes that represent approximately 80 % 

of the U.S. housing stock, including detached, attached, manufactured, and apartment 

buildings for use in indoor air quality research. The prototypes are based on the 

Residential Energy Consumption Survey (RECS) and American Housing Survey (AHS) 

databases. The study defines the conditioned floor area (CFA) and dimensions of 3 

different detached homes: 107.0 m2 (1152 ft2), 180.4 m2 (1942 ft2), and 275.5 m2

(2966 ft2

).3

Pacific Northwest National Laboratory (PNNL) published a report for the DOE Building 

Energy Codes Program that analyzes the state-level impacts of the adoption of 2009 

IECC for residential buildings.4 The study uses EnergyGauge (based on the DOE-2

whole building energy simulation software) to determine the energy use and cost savings

for a two-story, 223 m

2 (2400 ft2

) house.5

PNNL has created whole building energy simulations for two residential building 

designs, a single-family detached house and multifamily apartment building, based on the 

International Energy Conservation Code (IECC) Residential Code for One- and TwoStory Dwellings. EnergyPlus (E+) Version 5.0 energy simulations are generated for 119 

locations, 3 editions of the IECC (2006, 2009, and 2012), four heating system types, and 

four foundation types for a total of 11 424 simulations. All simulations are available on 

the DOE Building Energy Codes Program website.6 As of August 2012, the 

documentation for the whole building energy simulation designs is not publically 

available.

1.4 Approach

The prototype residential building designs in this report are based on a number of 

sources, including the research described above by Building America. Additional 

resources are RS Means cost databases, U.S. Census and Energy Information 

Administration (EIA) housing stock data, and a collection of ASHRAE standards and 

IECC codes. The prototype buildings are designed in the E+ Version 7.1 simulation 

software.7

 3 Persily et al. (2007) does not create 3-dimensional representations of the prototypical homes because it 

was not required for their analysis.

4 PNNL (2009) 5 The report does not specify the reasoning behind the building design selection.

6 Department of Energy (2012a) 7 Department of Energy (2012b)
3

Two prototypical residential building designs are documented in this report: one-story 

and two-story detached homes. The framework for these designs is the 2009 IECC 

Residential Code for One- and Two-Story Dwellings. IECC code defines the thermostat 

control, window specifications, exterior envelope R-values (m2-K/W), minimum lighting 

efficiency, maximum infiltration rates, mechanical ventilation, internal and structural 

mass, and heating, ventilating, and air-conditioning (HVAC) system requirements.

Although 2009 IECC defines the general construction requirements, the code does not 

address the building’s plug loads, occupancy, or geometry. Also lacking are a number of 

small but important details and assumptions required to effectively simulate the energy 

use of a residential building.

One source of this additional information is the Building America House Simulation 

Protocols (Hendron and Engebrecht, 2010), which is used for the annual loads, load 

profiles, and internal heat gains for lighting, occupancy, and domestic hot water as well 

as the outdoor air infiltration rate.

Prototypical building size and geometry are selected based on three sources. The U.S. 

Census Bureau Survey of Construction is used to determine the square footage and 

number of bedrooms for one-story and two-story residential detached buildings. The 

Annual 2010 Characteristics of New Housing released by the U.S. Census Bureau’s 

Manufacturing, Mining, and Construction Statistics Division and RSMeans Square Foot 

Costs (2011) are used to determine appropriate prototype building geometries.

Other codes and standards are needed to establish additional specifications: ASHRAE 

90.2-2007, ASHRAE 62.2-2010, and the ASHRAE Fundamentals Handbook. Their use 

will be defined in detail where appropriate in the remainder of the document.
4
5

2 One-Story Building Design Specification

The first building design represents a typical 1-story, 3-bedroom, slab-on-grade detached 

house with no garage. This design was chosen because it is the simplest building design 

and can be used as the framework for more detailed single-story house designs. In the 

remainder of this section, each aspect of the building design and operation will be 

defined.

2.1 Building Envelope

Some building envelope assumptions are constant regardless of the building location’s 

climate while other assumptions are specific to the climate zones shown in Figure A-1, 

which is located in the appendix due to the size of the map. The following two 

subsections will define each set of assumptions separately.

2.1.1 General Assumptions

The prototype is a 2009 IECC compliant 1-story, 3-bedroom, slab-on-grade house. The 

dimensions are 19.5 m x 7.6 m (64 ft x 25 ft) for a total of 148.6 m

2 (1,600 ft2

) of 

conditioned floor area (CFA). The house is oriented 19.5 m (64 ft) east to west and 7.6 m 

(25 ft) north to south. The first floor has a 2.4 m (8 ft) high ceiling. The roof slope is 

assumed to be 4:12 with 0.3 m (1 ft) overhangs on the north and south sides of the 

building. There is assumed to be no garage in the prototype.

The house is built to meet 2009 IECC for low-rise residential buildings. The EnergyPlus 

parameters for the materials used in the exterior envelope (excluding the roof) are 

estimated using an average transmittance with the surface-weighted path fractions. In 

other words, using a simple weighted average of parameter values based on the 

percentage of framing in the surface. The roof controls for varying materials by splitting 

the roof into two separate surfaces. The framing percentage for each surface type is 

shown in Table 2-1.

Table 2-1 Material Parameter Calculation Approach

Construction Pct. Frame Approach

Exterior Wall 23 % surface-weighted path fractions

Ceiling 11 % surface-weighted path fractions

Roof 11 % split into separate surfaces

The exterior wall is assumed to be 3.8 cm x 8.9 cm (1.5 in. x 3.5 in.) wood-framed 41 cm 

(16 in.) on center (OC) with 9 cm (3.42 in.) of fiberglass batt cavity insulation having a 
6

thermal resistance of 0.67 m

2

∙K/W (R-3.8 ft2∙0F∙h/Btu) per 2.5 cm (1 in.). The material 

layers for the exterior wall are defined in Figure 2-1. The construction is made of 5 or 6 

layers depending on IECC requirements: wood siding, a felt air barrier, rigid insulation 

(if required), plywood sheathing, 3.8 cm x 8.9 cm (1.5 in. x 3.5 in.) framing with batt 

insulation in wall cavity, and gypsum wall board (GWB).

Figure 2-1 Building material layers for exterior wall

The average conductance (U-factor) of the framing/insulation combination material is 

calculated by the following equation from ASHRAE Fundamentals Handbook (2009):

U AVG = 23%*UFRAME + 77%*UINSULATION

For this material, 23 % of the wall area is framing with the remaining 77 % being the 

wall cavity that is filled with cavity insulation.

The interior ceiling is assumed to be 1.3 cm (0.5 in.) GWB with 3.8 cm x 14.0 cm (1.5 in.

x 5.5 in.) ceiling joists. There is blown-in cellulose insulation in the open cavity plus any 

additional inches of blown-in insulation as required by 2009 IECC. The amount of 

blown-in insulation varies by climate zone, and will be described in Section 2.1.2. The 

average material U-factor is calculated in the same manner as the exterior wall for the 

wood frame/cavity layer. Framing accounts for 11 % of the ceiling surface. The material 

layers for the ceiling are defined in Figure 2-2.

Sheathing

Felt

Average of 

Insulation/ 

Wood Frame

GWB

Wood Siding

Rigid Insulation 

(if required)
7

Figure 2-2 Building material layers for ceiling

The roof construction is assumed to be 3.8 cm x 14.0 cm (1.5 in. x 5.5 in.) rafters with 

1.3 cm (0.5 in.) plywood sheathing, felt paper, and asphalt shingles. There is no 

insulation in the rafters, which makes it unnecessary to calculate an average U-factor. 

Instead the roof is split into two surfaces for energy simulation, one with framing (23 % 

of roof area) and one without framing (77 % of roof area). The material layers for the 

roof with framing are defined in Figure 2-3.

Figure 2-3 Building material layers for roof

The foundation is a 10 cm (4 in.) concrete slab. The floor finish is assumed to be 40 % 

carpet, 40 % hardwood, 15 % vinyl tile, and 5 % ceramic tile (based on RSMeans Square 

Foot Costs). Some climate zones require rigid insulation to be placed on the slab edge, 

which will be described in Section 2.1.2. The material layers for the slab are defined in 

Figure 2-4. The EnergyPlus Slab preprocessor is used to simulate the heat transfer 

between the ground and the slab, which recommends simulating horizontal insulation 

under the slab instead of vertical insulation on the edge of the slab for “slab-on-grade” 

foundations because the energy transfer that occurs on the vertical edges of the slab are 

significantly smaller than the energy transfer from the surface area contacting the ground.

The Slab preprocessor assumes that the bottom of the slab is flush with the grade.

Blown-In 

Insulation

GWB

Average of 

Insulation/ 

Wood Frame

Shingles

Wood Frame

Sheathing

Felt
8

Figure 2-4 Building material layers for slab-on-grade foundation

Window glazing area is assumed to be 15 % of conditioned floor area and is split 

between the four exterior walls based on wall area. Two 1.2 m (4 ft) high windows on 

each side of the house (8 in total) are assumed to be located equal distance from the wall 

edge. The width of the windows is based on the fraction of total wall area represented by 

each side. There are assumed to be two 0.9 m x 2.0 m (3 ft x 6 ft 8 in.) x 4.4 cm (1.75 in.)

solid pine wood doors, located in the center of the wall on the north and south walls. 

Windows are defined in EnergyPlus using the “Simple Glazing System,” which requires 

only 3 parameters: U-factor (W/ (m

2

∙K)), solar heat gain coefficient (SHGC), and visible 

transmittance (VT). These parameters vary by climate zone, and will be described in 

Section 2.1.2.

2.1.2 Climate Zone-Specific Assumptions

The exterior envelope performance requirements of 2009 IECC vary depending on the 

climate zone. Table 2-2 is an abridged version of Table 402.1.1 found in Chapter 4: 

Residential Energy Efficiency of the 2009 IECC. A map of the climate zones by county is 

found in the appendix.

Floor Finish

Concrete

Rigid Insulation 

(IECC Requirement)

Rigid Insulation 

(Simulated in E+)
9

Table 2-2 2009 IECC energy code requirements for exterior envelope

Climate Zone

Fenestration 

U-Factor 

(W/m2∙K)

Glazed 

Fenestration 

SHGC

Ceiling 

R-Value Wood Frame Wall R-Value Slab Edge 

R-Value Slab Depth

1 1.2 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

2 0.65 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

3 0.50 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

4 except Marine 0.35 NR* 6.7 (38) 2.3 (13) 1.8 (10) 0.61 m (2 ft)

5 and 4 Marine 0.35 NR* 6.7 (38) 3.5 (20) or 2.3+0.88 (13+5)** 1.8 (10) 0.61 m (2 ft)

6 0.35 NR* 8.6 (49) 3.5 (20) or 2.3+0.88 (13+5)** 1.8 (10) 1.21 m (4 ft)

7 and 8 0.35 NR* 8.6 (49) 3.7 (21) 1.8 (10) 1.21 m (4 ft)

*NR = No Requirement

**13+5 means R-13 cavity insulation plus R-5 insulated sheathing.

Note: R-value Units = m2∙K/W (ft2∙0F∙h/Btu)

Although EnergyPlus requires three parameters for defining window performance, 2009 

IECC only specifies two: U-factor and SHGC. The U-factor is restricted to below 1.2 in 

Zone 1 and becomes stricter the colder the climate zone, restricting the U-factor to below 

0.35 in Zone 7 and Zone 8. The SHGC must be less than 0.30 for Zone 1 through Zone 3, 

but has no requirement for Zone 4 through Zone 8. The SHGC for the standard reference 

design specified in 2009 IECC is 0.40 for Zone 4 through Zone 8. The visible 

transmittance is not restricted in 2009 IECC for any climate zones, and is assumed to be 

0.16 for Zone 1, 0.22 for Zone 2, 0.46 for Zone 3, and 0.40 for Zone 4 through Zone 8.

8

The insulation R-values for the exterior walls, ceiling, and foundation increase as the 

climate zone gets colder. The exterior wall R-value ranges from R-13 in Zone 1 through 

Zone 4 to R-21 in Zone 7 and Zone 8. The first R-13 is met with high density cavity

insulation in the wall cavity. Additional R-value is met by adding rigid insulation to the 

exterior of the wall. The ceiling R-value ranges from R-30 in Zone 1 through Zone 3 to 

R-49 in Zone 6 through Zone 8. Additional cellulose blown-in insulation is used to reach 

the required R-value. R-10 insulation under the foundation is required in Zone 4 through 

Zone 8 only, which is met by adding 2 in. of extruded polystyrene (XPS) below the slab.

 8 Visible transmittance values are based on window characteristics defined in the ASHRAE Fundamentals 

Handbook (2009). 
10

2.2 Heating, Ventilating, and Air Conditioning Equipment

The HVAC system in the prototype building design is a single-speed unitary system with 

an air conditioner with a seasonal energy efficiency ratio (SEER) rating of 13,

9 and a gas 

furnace with annual fuel utilization efficiency (AFUE) of 78 % (both current minimum 

federal energy efficiency requirements). No dehumidification option or economizer is 

included in the system. The supply fan is assumed to cycle, and has a total efficiency of 

70 %. The supply fan motor efficiency is 90 %. The ductwork is assumed to be within the 

conditioned space, which leads to zero energy loss from the ductwork. This assumption 

assists in simplifying the model, and will be relaxed in future research to account for split 

systems and the resulting duct leakage.10

2.3 Operating Conditions

The thermostat setpoints are based on the standard reference designs defined in 2009 

IECC, which are 23.9°C (75°F) cooling and 22.2°C (72°F) heating.

2.4 Outdoor Air Ventilation and Infiltration

The prescriptive maximum air leakage of 7 air changes per hour at 50 pascals (ACH50)

specified in Section 402.4.2.1 of the 2009 IECC is not defined under normal operating 

conditions. The air infiltration rate must be converted into effective leakage area (ELA), 

which requires two conversions. First, the ACH50 is converted into cubic feet per minute 

at 50 pascals (CFM50) based on the following equation.

CFM50 = ACH50 ∗

Volume[ft3]

60 = 7 ∗

12800

60 = 1493

Second, the following equation from Lawrence Berkeley Laboratory (LBL) converts the 

CFM50 into an ELA of 520 cm

2 (0.56 ft2

).

11

ELA = CFM50

2700 = 0.55 ft2 = 520 cm2

Previous editions of the IECC do not specify the air infiltration rate. The air infiltration 

rate for these prototypes will use the following equation from Hendron and Engebrecht 

 9 The 13 SEER rating converts to a Coefficient of Performance (COP) of 3.28 for the EnergyPlus 

simulation based on the following equation: COP = (−0.02 ∗ SEER2 + 1.12 ∗ SEER)/3.412. 10 The 2009 IECC prescriptive requirements include a duct tightness post-construction test showing duct 

leakage less than or equal to 226.5 L/min (8 CFM) per 9.29 m2 (100 ft2

) at 25 Pascal (Pa). 11 LBL (2012)
11

(2010), where the ELA is the specific leakage area (SLA) multiplied by the conditioned 

floor area (CFA).12

ELA = SLA ∗ CFA

Table 405.5.2(1) of the 2009 IECC specifies that for “residences with mechanical 

ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air 

exchange rate combined with the mechanical ventilation rate...shall not be less than” the 

ASHRAE 62.2-2010 minimum outdoor air flow rate. 

The minimum mechanical ventilation rate based on ASHRAE Standard 62.2-2010 (liters 

per second) is calculated using ASHRAE 62.2-2010 equation 4.1b:

0.05 ∗ m2 + 3.5 ∗ (NBR + 1)

For the prototype design’s 148.6 m

2 (1600 ft2

) and 3 bedrooms, the total outdoor air rate 

is 0.022 m3 per second (46 CFM), which converts to 0.22 ACH. The 2009 IECC

maximum air infiltration rate of 7 ACH50 can be converted into a relative natural air 

change per hour (ACHNAT) with the following equation from Environmental Protection 

Agency (EPA) (2001), where the LBL Factor ranges from 14 to 26 and the Location 

Factor ranges from 0.72 to 1.00.

ACHNAT = ACH50

LBL Factor ∗ Location Factor

The ACHNAT will range between 0.27 and 0.50. Since the air infiltration ACH is always 

greater than the minimum ventilation rate defined in ASHRAE 62.2-2010, no mechanical 

ventilation is required.

Based on ASHRAE 90.2-2007, an additional 0.15 ACH is added to the model for 

occupant activity, such as window and door operation and running exhaust fans.

13

Based on Hendron and Engebrecht (2010) and the 2009 IECC, the attic ventilation is 

equivalent to 1 unit per 300 units of the ceiling area, which converts to an effective 

leakage area (ELA) of 4955 cm

2 (5.33 ft2

).

2.5 Domestic Hot Water

The BA Protocol functions defined in Table 2-3 are used instead of 2009 IECC to 

estimate the hot water consumption of each piece of equipment and activities. Total hot 

water consumption based on the BA Protocol is 228 liters (60 gallons). These estimates 

 12 All values in the same units. 13 According to the ASHRAE Fundamentals Handbook, “In residences...air exchange associated with a 

door can be estimated based on air leakage through cracks between door and frame.”
12

are used for the analysis because they break down consumption by end use; the 2009 

IECC estimate is for total hot water consumption only. The clothes washer and 

dishwasher use only hot water at 48.9°C (120°F) while the showers, baths, and sinks use 

hot water that is tempered to 43.3°C (110°F), as shown in Table 2-3.

Table 2-3 Hot Water Consumption

Equipment Water Temp. Function 

Liters (Gallons)

Liters (Gallons) 

Per Day

Clothes Washer 48.9°C (120°F) 8.9+3.0* NBR (2.35+0.78*NBR) 19 (5)

Dishwasher 48.9°C (120°F) 8.6+2.8* NBR (2.26+0.75*NBR) 19 (5)

Showers 43.3°C (110°F) 53.0+17.7* NBR (14+4.67*NBR) 68 (18)

Baths 43.3°C (110°F) 13.2+4.4* NBR (3.5+1.17*NBR) 27 (7)

Sinks 43.3°C (110°F) 47.3+15.7* NBR (12.5+4.16*NBR) 95 (25)

Total: 228 (60)

The BA Protocol total water use, daily water use load profiles, and sensible (temperaturebased) and latent (humidity-based) loads for hot water use are used to estimate the real 

time hot water use and the resulting internal heat gains. The daily load profile, or 

proportion of peak flow rate by hour of the day, for each hot water use category can be 

seen in Figure 2-5.
13

Figure 2-5 Domestic Hot Water Load Profiles as a Proportion of Peak Flow Rate, 

By Hour of the Day

Based on the BA Protocol, internal heat gains from hot water for the clothes washer and 

dishwasher are assumed to be zero for both sensible and latent loads. Any heat gains for 

this equipment are included in the equipment electricity use heat gains. The sensible and 

latent load fractions for shower, bath, and sinks are reverse engineered from internal heat 

gains estimated using the BA Protocol functions in Table 2-4.

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Washer

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Dish Washer

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Bath

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Shower

0.0

0.5

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Sinks
14

Table 2-4 Domestic Hot Water Daily Internal Heat Gains

Equipment 

End Use

Sensible Load Latent Load

Function 

kWh (Btu)

Heat Gain 

kWh (Btu)

Load 

Fraction

Function 

kWh (Btu)

Heat Gain 

kWh (Btu)

Load 

Fraction

Showers 0.22+0.07*NBR

(741+247*NBR)

0.4 (1482) 0.1947 0.21+0.07* NBR

(703+235*NBR)

0.4 (1408) 0.0055

Baths 0.05+0.02* NBR

(185+62*NBR)

0.4 (1371) 0.7262 0 (0) 0 (0) 0.0000

Sinks 0.09+0.03*NBR

(310+103*NBR)

0.2 (619) 0.0917 0.04+0.01* NBR

(140+47*NBR)

0.1 (281) 0.0012

Based on 2009 IECC, the water heater must meet federal energy efficiency requirements. 

The water heater is assumed to be a gas water heater with a perfectly mixed storage tank 

with an efficiency of 76 %,

14 a firing rate of 10 554 W,15 and a setpoint temperature of 

48.9°C (120°F). The heat loss coefficient from the water heater to the ambient 

temperature in the internal space is assumed to be 2.1 W/K.

16

2.6 Lighting

The lighting load profiles and electricity consumption are based on the simplest profile in 

the BA Protocol, which varies by time of day, but not from day to day. Total electricity 

use is estimated based on the two-stage process defined in the BA Protocol as expressed 

in Table 2-5. The baseline lighting estimate is based on 66 % incandescent, 21 % 

compact fluorescent (CFL), and 13 % T-8 linear fluorescent use. The lighting 

requirements in 2009 IECC require 50 % high efficacy lights for all hard-wired lighting, 

which is met by shifting 16 % of all hard-wired lighting from incandescent to CFL. The 

BA Protocol adjustment functions shown on the right in Table 2-5 are used to adjust the 

total electricity consumption estimate to represent the greater efficiency required by 2009 

IECC. The baseline total lighting electricity consumption is estimated at 1918 kWh. The 

2009 IECC-compliant lighting decreases lighting electricity consumption by 22 %.

 14 Minimum federal efficiency requirement for gas water heaters. 15 Based on the BA Benchmark for a 3 bedroom/2 bathroom house with a gas unit. 16 Based on NIST expert recommendation.
15

Table 2-5 Annual Lighting Electricity Consumption

Lighting 

Use 

Category

Baseline 2009 IECC-Compliant

Function kWh Function kWh

Hard-wired 0.8*(CFA*0.542+334) 961 *{[(FINC+0.34) + (FCFL-0.21)*0.27 + 

(FLF-0.13)*0.17]*SAF*0.9+0.1} 751

Plug-In 0.2*(CFA*0.542+334) 240 240

Exterior CFA*0.145 232 *{[(FINC+0.34) + (FCFL-0.21)*0.27 + 

(FLF-0.13)*0.17]*0.9+0.1} 208

Total 1433 1199

FINC = Fraction incandescent

FCFL = Fraction compact fluorescent

FLF = Fraction linear fluorescent

SAF = Smart replacement algorithm factor = 1.1*FInc4-1.9* FInc3+1.5* FInc2-0.7* FInc+1

The load profile (proportion of peak wattage in use) for interior lighting can be seen in

Table 2-6. The total wattage parameter for lighting in E+ is reverse engineered from the 

peak consumption load profile and the total electricity consumption estimate. The load 

profile for exterior lighting assumes the lights are on sunset to sunrise.

Table 2-6 Lighting Load Profile as Proportion of Peak Wattage in Use, by Hour of 

the Day

Hour Load Profile Hour Load Profile

1:00 0.067 13:00 0.119

2:00 0.067 14:00 0.119

3:00 0.067 15:00 0.119

4:00 0.067 16:00 0.206

5:00 0.187 17:00 0.439

6:00 0.394 18:00 0.616

7:00 0.440 19:00 0.829

8:00 0.393 20:00 0.986

9:00 0.172 21:00 1.000

10:00 0.119 22:00 0.692

11:00 0.119 23:00 0.384

12:00 0.119 24:00 0.16
16

Monthly multipliers defined in Hendron and Engebrecht (2010) are used to account for 

the variation across the year in lighting use. The load profile in Table 2-6 is adjusted by 

the multiplier for each month.

2.7 Appliances and Miscellaneous Electrical Loads

The electrical equipment in the house includes a refrigerator, clothes washer, clothes 

dryer, dishwasher, electric range, and a combination of variable miscellaneous electrical 

loads (MELs). MELs encompass electronics such as computers, televisions, stereos, and 

other plug loads. The electricity consumption for each category is based on the BA 

Protocol functions seen in Table 2-7. Electricity consumption is usually a function of the 

number of bedrooms in the home (NBR). 

Table 2-7 Appliance and MEL Electricity Consumption

Equipment Function kWh

Refrigerator Constant 434

Clothes Washer 38.8+12.9*NBR 78

Clothes Dryer 538.2+179.4* NBR 1076

Dishwasher 87.6+29.2* NBR 175

Electric Range 250+83* NBR 499

Variable MELs 1703+ (266* NBR) + (0.454*CFA) 3227

Total: 5489

Source: Hendron and Engebrecht (2010)

The BA Protocol load profiles in Figure 2-6 create a real-time variation in electricity 

consumption for each category. Appliances such as the electric range and dishwasher 

have a significant variation in time-of-day use while refrigerator use only varies slightly 

over a day.
17

Figure 2-6 Electrical Equipment Load Profiles as a Proportion of Peak Wattage, By 

Hour of the Day

2.8 Internal Mass

Instead of defining individual interior surfaces and furniture, internal mass is estimated 

based on ASHRAE 90.2-2007 recommendations. There is assumed to be 3.6 kg (8 lb) of 

5 cm (2 in.) thick wood per square foot of conditioned space for contents for a total of 

5806 kg (12 800 lb). There is assumed to be 2.3 kg (5 lb) of 1.3 cm (0.5 in.) gypsum wall 

board (GWB) per square foot of conditioned space for the internal structure for a total of 

3629 kg (8000 lb). 

E+ estimates internal mass in terms of square meters of material open to the zone air. 

Based on the total weight of the two materials (wood and GWB) and their weight per unit 

0.00

0.02

0.04

0.06

0.08

0.10

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Washer

0.00

0.05

0.10

0.15

1 3 5 7 9 11 13 15 17 19 21 23

Dishwasher

0.00

0.02

0.04

0.06

1 3 5 7 9 11 13 15 17 19 21 23

Refrigerator

0.00

0.02

0.04

0.06

0.08

0.10

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Dryer

0.00

0.05

0.10

0.15

0.20

1 3 5 7 9 11 13 15 17 19 21 23

Range

0.00

0.02

0.04

0.06

0.08

1 3 5 7 9 11 13 15 17 19 21 23

MELs
18

of thickness, it is possible to determine the comparable surface area needed to match the 

amount of internal mass required. Assuming the wood density is equivalent to that of 

white oak, 753 kg/m3 (47 lb/ft3), the 5 cm (2 in.) thick wood weighs 38 kg/m

2 (7.833 

lb/ft2) and would require 151.8 m

2 (1634 ft2

) of content mass. Assuming GWB density of 

10 kg/m

2 (2.08 lb/ft2

), a total of 357.3 m

2 (3846 ft2

) of structural mass is required to meet 

the standard recommendation.

2.9 Occupancy

Occupancy is based on the BA Protocol constant daily occupancy load profile seen in 

Table 2-8. The profile changes over the hours of the day, but does not vary across days. 

The house is treated as a single zone with an average internal heat gain of 113 watts per 

person (385.8 Btu/person/hr). The average number of people varies between all three 

family members being at home during the night to only 0.73 people present during the 

middle of the day.

Table 2-8 Occupancy Load Profile as a Proportion of Maximum Occupancy, and 

Total Occupants, By Hour of the Day

Hour Load Profile People Hour Load Profile People

1:00 1.000 3.00 13:00 0.242 0.73

2:00 1.000 3.00 14:00 0.242 0.73

3:00 1.000 3.00 15:00 0.242 0.73

4:00 1.000 3.00 16:00 0.242 0.73

5:00 1.000 3.00 17:00 0.295 0.89

6:00 1.000 3.00 18:00 0.553 1.66

7:00 1.000 3.00 19:00 0.897 2.69

8:00 0.883 2.65 20:00 0.897 2.69

9:00 0.409 1.23 21:00 0.897 2.69

10:00 0.242 0.73 22:00 1.000 3.00

11:00 0.242 0.73 23:00 1.000 3.00

12:00 0.242 0.73 24:00 1.000 3.00

2.10 Internal Heat Gains

Internal heat gains originate from domestic hot water use, electrical equipment use, 

lighting, and human occupancy. Previous sections have addressed specific internal heat 

gain categories, but it is of interest to summarize these heat gains and determine if they 

are comparable to the 2009 IECC standard reference design specifications. The total 

internal heat gains specified by 2009 IECC are based on the following equation.

CFA NBR IGain =17,900 + 23.8* + 4104*
19

Based on 2009 IECC, total internal heat gains, IGain, should be 20 001 kWh/day (68 292 

Btu/day) for the one-story prototype. The internal heat gains resulting from each category 

based on an EnergyPlus simulation of the prototype are shown in Table 2-9. The 

simulated internal heat gains of 19.0 kWh/day (64 905 Btu/day) are comparable, though 

slightly lower, than the 2009 IECC standard reference design (5 %). The minimal 

difference shows that the E+ model performs similar to the heat gain targets for 2009 

IECC.

Table 2-9 Daily Heat Gain Comparison-Reference and Prototype Designs

Equipment BA Protocol

kWh (Btu)

2009 IECC 

kWh (Btu)

Prototype Design 

kWh (Btu)

Lighting Not Specified Not Specified 2.7 (9266)

Equipment 11.2 (38 142) Not Specified 10.7 (36 511)

Occupancy 5.6 (19 140) Not Specified 5.6 (19 128)

Hot Water 1.2 (4161) Not Specified 1.3 (4420)

Total Not Specified 20.0 (68 292) 19.0 (64 905)
20
21

3 Two-Story Building Design Specification

The second building design represents a typical 2-story, 3-bedroom, slab-on-grade 

detached house with no garage. This design was chosen because it is the simplest 

building design and can be used as the framework for more detailed 2-story house 

designs. In the remainder of this section, each aspect of the building design and operation 

will be defined.

3.1 Building Envelope

There are some building envelope assumptions that are constant regardless of the 

building location’s climate while other assumptions are climate specific. The following 

two subsections will define each set of assumptions separately.

3.1.1 General Assumptions

The prototype is a 2009 IECC compliant 2-story, 3-bedroom, slab-on-grade house. The 

dimensions are 12.8 m x 8.0 m (42 ft x 26.25 ft) for a total of 204.9 m

2 (2205 ft2

) of 

conditioned floor area. The house is oriented 12.8 m (42 ft) east to west and 8.0 m 

(26.25 ft) north to south. The first and second floors have 2.4 m (8 ft) high ceilings. The 

roof slope is assumed to be 4:12 with 0.3 m (1 ft) overhangs on the north and south sides 

of the building. There is assumed to be no garage in the prototype.

The house is built to meet 2009 IECC for low-rise residential buildings. The EnergyPlus 

parameters for the materials used in the exterior envelope (excluding the roof) are 

estimated using an average transmittance with the surface-weighted path fractions. In 

other words, using a simple weighted average of parameter values based on the 

percentage of framing in the surface. This approach is reasonable for materials with 

similar R-values and thickness. The roof and interior floor control for varying materials 

by splitting the surface into two separate surfaces. The framing percentage for each 

surface type is shown in Table 3-1.

Table 3-1 Material Parameter Calculation Approach

Construction Pct. Frame Approach

Exterior Wall 23 % surface-weighted path fractions

Top Floor Ceiling 11 % surface-weighted path fractions

Roof 11 % split into separate surfaces

Interior Floor 13 % split into separate surfaces
22

The exterior wall is assumed to be 3.8 cm x 8.9 cm (1.5 in. x 3.5 in.) wood-framed 41 cm

(16 in.) on center (OC) with 9 cm (3.42 in.) of fiberglass batt cavity insulation in.)having

a thermal resistance of R-3.8 per 2.5 cm (1 in.)). The material layers for the exterior wall 

are defined in Figure 3-1. The construction is made of 5 or 6 layers depending on IECC 

requirements: wood siding, a felt vapor barrier, rigid insulation (if required), plywood 

sheathing, 3.8 cm x 8.9 cm (1.5 in. x 3.5 in.) framing with batt insulation in wall cavity, 

and gypsum wall board (GWB).

Figure 3-1 Building material layers for exterior wall

The average conductance (U-factor) of the framing/insulation combination material is 

calculated by the following equation from ASHRAE Fundamentals Handbook (2009):

U AVG = 23%*UFRAME + 77%*UINSULATION

For this material, 23 % of the wall area is framing with the remaining 77 % being the 

wall cavity that is filled with cavity insulation.

The second floor ceiling is assumed to be 1.3 cm (0.5 in.) GWB with 3.8 cm x 14.0 cm

(1.5 in. x 5.5 in.) ceiling joists. There is blown-in cellulose insulation in the open cavity 

plus any additional inches of blown-in insulation as required by 2009 IECC. The amount 

of blown-in insulation varies by climate zone, and will be described in Section 3.1.2. The 

average material U-factor is calculated in the same manner as the exterior wall. Framing 

accounts for 11 % of the ceiling surface. The material layers for the ceiling are defined in 

Figure 3-2.

Sheathing

Felt

Average of 

Insulation/ 

Wood Frame

GWB

Wood Siding

Rigid Insulation 

(if required)
23

Figure 3-2 Building material layers for ceiling

The roof construction is assumed to be 3.8 cm x 14.0 cm (1.5 in. x 5.5 in.) rafters with 

1.3 cm (0.5 in.) plywood sheathing, felt paper, and asphalt shingles. There is no 

insulation in the rafters, which makes it unrealistic to calculate an average U-factor. 

Instead the roof is split into two surfaces for energy simulation, one with framing (23 % 

of roof area) and one without framing (77 % of roof area). The material layers for the 

roof with framing are defined in Figure 3-3.

Figure 3-3 Building material layers for roof

The interior floor/ceiling (first level ceiling/second level floor) construction is assumed to 

be 3.8 cm x 19.1 cm (1.5 in. x 7.5 in.) floor joists with 1.6 cm (5/8 in.) plywood 

subflooring and 100% carpet finish. The framing accounts for 13 % of the floor. No 

insulation is required for interior surfaces because there is no thermal benefit from 

restricting thermal transfer within the same zone.

The foundation is a 10 cm (4 in.) concrete slab. The floor finish is assumed to be 40 % 

carpet, 40 % hardwood, 15 % vinyl tile, and 5 % ceramic tile (based on RSMeans Square 

Foot Costs). Some climate zones require rigid insulation to be placed on the slab edge, 

which will be described in Section 3.1.2. The material layers for the slab are defined in 

Figure 3-4. The EnergyPlus Slab preprocessor is used to simulate the heat transfer 

between the ground and the slab, which recommends simulating horizontal insulation 

Blown-In 

Insulation

GWB

Average of 

Insulation/ 

Wood Frame

Shingles

Wood Frame

Sheathing

Felt
24

under the slab instead of vertical insulation on the edge of the slab for “slab-on-grade” 

foundations because the energy transfer that occurs on the vertical edges of the slab are 

significantly smaller than the energy transfer from the surface area contacting the ground. 

The Slab preprocessor assumes that the bottom of the slab is flush with the grade.

Figure 3-4 Building material layers for slab-on-grade foundation

Window glazing area is assumed to be 15 % of conditioned floor area and is split 

between the four exterior walls based on wall area. Two 1.2 m (4 ft) high windows on 

each side of the house for each floor (16 in total) are assumed to be located at an equal 

distance from the wall edge. The width of the windows is based on the fraction of total 

wall area represented by each side. There are assumed to be two 0.9 m x 2.0 m (3 ft x 6 ft

8 in.) – 4.4 cm (1.75 in.) solid pine wood doors, located in the center of the wall on the 

north and south walls. Windows are defined in EnergyPlus using the “Simple Glazing 

System,” which requires only 3 parameters: U-factor (W/m2

∙K), solar heat gain 

coefficient (SHGC), and visible transmittance (VT). These parameters vary by climate 

zone, and will be described in Section 3.1.2.

3.1.2 Climate Zone-Specific Assumptions

The exterior envelope performance requirements of 2009 IECC vary depending on the 

climate zone. Table 3-2 is an abridged version of Table 402.1.1 found in Chapter 4: 

Residential Energy Efficiency of the 2009 IECC. A map of the climate zones by county is 

found in the appendix.

Floor Finish

Concrete

Rigid Insulation 

(IECC Requirement)

Rigid Insulation 

(Simulated in E+)
25

Table 3-2 2009 IECC energy code requirements for exterior envelope

Climate Zone Fenestration 

U-Factor 

(W/m2∙K)

Glazed 

Fenestration 

SHGC

Ceiling 

R-Value 

Wood Frame Wall R-Value Slab Edge 

R-Value 

Slab Depth

1 1.2 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

2 0.65 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

3 0.50 0.30 5.3 (30) 2.3 (13) 0 (0) 0 (0)

4 except Marine 0.35 NR* 6.7 (38) 2.3 (13) 1.8 (10) 0.61 m (2 ft)

5 and 4 Marine 0.35 NR* 6.7 (38) 3.5 (20) or 2.3+0.88 (13+5)** 1.8 (10) 0.61 m (2 ft)

6 0.35 NR* 8.6 (49) 3.5 (20) or 2.3+0.88 (13+5)** 1.8 (10) 1.21 m (4 ft)

7 and 8 0.35 NR* 8.6 (49) 3.7 (21) 1.8 (10) 1.21 m (4 ft)

*NR = No Requirement

**13+5 means R-13 cavity insulation plus R-5 insulated sheathing.

Note: R-value Units = m2∙K/W (ft2∙0F∙h/Btu)

Although EnergyPlus requires three parameters to define windows, 2009 IECC only 

specifies two: U-factor and SHGC. The U-factor is allowed to be as high as 1.2 in Zone 1 

to as low as 0.35 in Zone 7 and Zone 8. The SHGC must be less than 0.30 for Zone 1

through Zone 3, but has no requirement for Zone 4 through Zone 8. The SHGC for the 

standard reference design specified in 2009 IECC is 0.40 for Zone 4 through Zone 8. The 

visible transmittance is not restricted in 2009 IECC for any climate zones, and is assumed 

to be 0.16 for Zone 1, 0.22 for Zone 2, 0.46 for Zone 3, and 0.40 for Zone 4 through 

Zone 8.17

The insulation R-values for the exterior walls, ceiling, and foundation increase as the 

climate zone gets colder. The exterior wall R-value ranges from R-13 in Zone 1 through 

Zone 4 to R-21 in Zone 7 and Zone 8. The first R-13 is met with high density cavity

insulation in the wall cavity. Additional R-value is met by adding rigid insulation to the 

exterior of the wall. The ceiling R-value ranges from R-30 in Zone 1 through Zone 3 to 

R-49 in Zone 6 through Zone 8. Additional cellulose blown-in insulation is used to reach 

the required R-value. R-10 insulation under the foundation is required in Zone 4 through 

Zone 8 only, which is met by adding 10 cm (2 in.) of extruded polystyrene (XPS) below 

the slab.

 17 Visible transmittance values are based on window characteristics defined in the ASHRAE Fundamentals 

Handbook (2009). 
26

3.2 Heating, Ventilating, and Air Conditioning Equipment

As in the one-story model, the HVAC system in the prototype building design is a singlespeed unitary system with an air conditioner with a seasonal energy efficiency ratio 

(SEER) rating of 13,

18 and a gas furnace with annual fuel utilization efficiency (AFUE) 

of 78 % (both current minimum federal energy efficiency requirements). No 

dehumidification option or economizer is included in the system. The supply fan is 

assumed to cycle, and has a total efficiency of 70 %. The supply fan motor efficiency is 

90 %. The first and second floors are assumed to be a single zone, with the HVAC 

equipment located on the first floor. The ductwork is assumed to be within the 

conditioned space, which leads to zero energy loss from the ductwork. These two 

assumptions assist in simplifying the model, and will be relaxed in future research to 

account for split systems and the resulting duct leakage.19

3.3 Operating Conditions

As in the one-story model, the thermostat setpoints are based on the standard reference 

designs defined in 2009 IECC, which are 23.9 °C (75°F) cooling and 22.2 °C (72°F) 

heating.

3.4 Air Infiltration and Mechanical Ventilation

The prescriptive maximum air leakage of 7 air changes per hour at 50 pascals (ACH50)

specified in Section 402.4.2.1 of the 2009 IECC is not defined under normal operating 

conditions. The air infiltration rate must be converted into effective leakage area (ELA), 

which requires two conversions. First, the ACH50 is converted into cubic feet per minute 

at 50 pascals (CFM50) based on the following equation.

CFM50 = ACH50 ∗

Volume[ft3]

60 = 7 ∗

17640

60 = 2058

Second, the following equation from Lawrence Berkeley Laboratory (LBL) converts the 

CFM50 into an ELA of 717 cm2 (0.77 ft2).

20

ELA = CFM50

2700 = 0.76 ft2 = 717 cm2

 18 The 13 SEER rating converts to a Coefficient of Performance (COP) of 3.28 for the EnergyPlus 

simulation based on the following equation: COP = (−0.02 ∗ SEER2 + 1.12 ∗ SEER)/3.412. 19 2009 IECC prescriptive requirements include a duct tightness post-construction test showing duct 

leakage less than or equal to 226.5 L/min (8 CFM) per 9.29 m2 (100 ft2

) at 25 Pascal (Pa). 20 LBL (2012)
27

Previous editions of the IECC do not specify the air infiltration rate. The air infiltration 

rate for these prototypes will use the following equation from Hendron and Engebrecht 

(2010), where the ELA is the specific leakage area (SLA) multiplied by the conditioned 

floor area (CFA).21

ELA = SLA ∗ CFA

Table 405.5.2(1) of the 2009 IECC specifies that for “residences with mechanical 

ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air 

exchange rate combined with the mechanical ventilation rate...shall not be less than” the 

ASHRAE 62.2-2010 minimum outdoor air flow rate. 

The minimum mechanical ventilation rate based on ASHRAE Standard 62.2-2010 (liters 

per second) is calculated using ASHRAE 62.2-2010 equation 4.1b:

0.05 ∗ m2 + 3.5 ∗ (NBR + 1)

For the prototype design’s 204.9 m

2 (2205 ft2

) and 3 bedrooms, the total outdoor air rate 

is 0.024 m3 per second (51 CFM), which converts to 0.17 ACH. The 2009 IECC 

maximum air infiltration rate of 7 ACH50 can be converted into a relative natural air 

change per hour (ACHNAT) with the following equation from EPA (2001), where the LBL 

Factor ranges from 14 to 26 and the Location Factor ranges from 0.72 to 1.00.

ACHNAT = ACH50

LBL Factor ∗ Location Factor

The ACHNAT will range between 0.27 and 0.50. Since the air infiltration ACH is always 

greater than the minimum ventilation rate defined in ASHRAE 62.2-2010, no mechanical 

ventilation is required.

Based on ASHRAE 90.2-2007, an additional 0.15 ACH is added to the model for 

occupant activity, such as window and door operation and running exhaust fans.

22

Based on Hendron and Engebrecht (2010) and the 2009 IECC, the attic ventilation is 

equivalent to 1 unit per 300 units of the ceiling area, which converts to an effective 

leakage area (ELA) of 6829 cm

2 (7.4 ft2

).

3.5 Domestic Hot Water

As in the one-story model, the BA Protocol functions defined in Table 3-3 are used 

instead of 2009 IECC to estimate the hot water consumption of each piece of equipment 

 21 All values in the same units. 22 According to the ASHRAE Fundamentals Handbook, “In residences...air exchange associated with a 

door can be estimated based on air leakage through cracks between door and frame.”
28

and activities. Total hot water consumption based on the BA Protocol is 228 liters (60 

gallons) which is the same as in the one-story prototype because the number of bedrooms 

is equal. These estimates are used for the analysis because they break down consumption 

by end use; the 2009 IECC estimate is for total hot water consumption only. The clothes 

washer and dishwasher use only hot water at 48.9°C (120°F) while the showers, baths, 

and sinks use hot water that is tempered to 43.3°C (110°F), as shown in Table 3-3.

Table 3-3 Hot Water Consumption

Equipment Water Temp. Function 

Liters (Gallons)

Liters (Gallons) 

Per Day

Clothes Washer 48.9°C (120°F) 8.9+3.0* NBR (2.35+0.78*NBR) 19 (5)

Dishwasher 48.9°C (120°F) 8.6+2.8* NBR (2.26+0.75*NBR) 19 (5)

Showers 43.3°C (110°F) 53.0+17.7* NBR (14+4.67*NBR) 68 (18)

Baths 43.3°C (110°F) 13.2+4.4* NBR (3.5+1.17*NBR) 27 (7)

Sinks 43.3°C (110°F) 47.3+15.7* NBR (12.5+4.16*NBR) 95 (25)

Total: 228 (60)

The BA Protocol total water use, daily water use load profiles, and sensible (temperaturebased) and latent (humidity-based) loads for hot water use are used to estimate the realtime hot water use and the resulting internal heat gains. The daily load profiles, or 

proportion of peak flow rate by hour of the day, for each hot water use category can be 

seen in Figure 3-5.
29

Figure 3-5 Domestic Hot Water Load Profiles as a Proportion of Peak Flow Rate, 

By Hour of the Day

Based on the BA Protocol, internal heat gains from hot water for the clothes washer and 

dishwasher are assumed to be zero for both sensible and latent loads. Any heat gains for 

this equipment are included in the equipment electricity use heat gains. The sensible and 

latent load fractions for shower, bath, and sinks are reverse engineered from internal heat 

gains estimated using the BA Protocol functions in Table 3-4.

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Washer

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Dishwasher

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Bath

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Shower

0.0

0.2

0.4

0.6

0.8

1.0

1 3 5 7 9 11 13 15 17 19 21 23

Sinks
30

Table 3-4 Domestic Hot Water Internal Heat Gains

Equipment 

End Use

Sensible Load Latent Load

Function 

kWh (Btu)

Heat Gain 

kWh (Btu)

Load 

Fraction

Function 

kWh (Btu)

Heat Gain 

kWh (Btu)

Load 

Fraction

Showers 0.22+0.07*NBR

(741+247*NBR)

0.4 (1482) 0.1947 0.21+0.07* NBR

(703+235*NBR)

0.4 (1408) 0.0055

Baths 0.05+0.02* NBR

(185+62*NBR)

0.4 (1371) 0.7262 0 (0) 0 (0) 0.0000

Sinks 0.09+0.03*NBR

(310+103*NBR)

0.2 (619) 0.0917 0.04+0.01* NBR

(140+47*NBR)

0.1 (281) 0.0012

Based on 2009 IECC, the water heater must meet federal energy efficiency requirements. 

The water heater is assumed to be a gas water heater with a perfectly mixed storage tank 

with an efficiency of 76 %,

23 a firing rate of 10 551 W,24 and a setpoint temperature of 

48.9°C (120 °F). The heat loss coefficient from the water heater to the ambient 

temperature in the internal space is assumed to be 2.1 W/K.25

3.6 Lighting

The lighting load profiles and electricity consumption are based on the profile in the BA 

Protocol that separates the house into living and sleeping zones.

26 Total electricity use is 

estimated based on the same two-stage process defined in the BA Protocol except the 

loads are split equally between the two floors, which can be seen in Table 3-5. The 

baseline lighting estimate is based on 86 % incandescent and 14 % fluorescent use. The 

lighting requirements in 2009 IECC require 50 % high efficacy lighting, which is met by 

using 50 % CFL lighting. The BA Protocol adjustment functions shown in the right in 

Table 3-5 are used to adjust the total electricity consumption estimation to represent the 

greater efficiency required by 2009 IECC. The baseline annual total lighting electricity 

consumption is estimated at 2281 kWh. The 2009 IECC compliant lighting decreases 

lighting electricity consumption by 36 % to 1411 kWh.

 23 Minimum federal efficiency requirement for gas water heaters. 24 Based on the BA Benchmark for a 3 bedroom/2 bathroom house with a gas unit. 25 Based on NIST expert recommendation. 26 Splitting the lighting loads profiles will allow an easier transition if multiple zoning options are 

introduced into the prototypes in the future.
31

Table 3-5 Annual Lighting Electricity Consumption

Lighting 

Use 

Category

Baseline 2009 IECC-Compliant

Function kWh Function kWh

Hard-wired 0.8*(CFA*0.542+334) 1223 *{[(FINC+0.34) + (FCFL-0.21)*0.27 + 

(FLF-0.13)*0.17]*SAF*0.9+0.1} 955

Plug-In 0.2*(CFA*0.542+334) 306 306

Exterior CFA*0.145 320 *{[(FINC+0.34) + (FCFL-0.21)*0.27 + 

(FLF-0.13)*0.17]*0.9+0.1} 286

Total 1849 1547

FINC = Fraction incandescent

FCFL = Fraction compact fluorescent

FLF = Fraction linear fluorescent

SAF = 1.1*FInc4-1.9* FInc3+1.5* FInc2-0.7* FInc+1

The load profiles (proportion of peak wattage in use) for interior lighting can be seen in 

Table 3-6. The total wattage parameter for lighting in EnergyPlus is reverse engineered 

from the peak consumption load profiles and the total electricity consumption estimates. 

The load profile for exterior lighting assumes the lights are on sunset to sunrise.

Table 3-6 Lighting Load Profiles as a Proportion of Peak Wattage in Use, By Hour 

of the Day

Hour Living Sleeping Hour Living Sleeping

1:00 0.060 0.670 13:00 0.139 0.067

2:00 0.060 0.670 14:00 0.139 0.067

3:00 0.060 0.670 15:00 0.139 0.067

4:00 0.060 0.670 16:00 0.259 0.084

5:00 0.120 0.267 17:00 0.549 0.183

6:00 0.240 0.584 18:00 0.766 0.266

7:00 0.279 0.634 19:00 0.945 0.499

8:00 0.269 0.533 20:00 1.000 0.800

9:00 0.139 0.200 21:00 0.901 1.000

10:00 0.139 0.067 22:00 0.518 0.867

11:00 0.139 0.067 23:00 0.278 0.496

12:00 0.139 0.067 24:00 0.120 0.200
32

Monthly multipliers defined in Hendron and Engebrecht (2010) are used to account for 

the variation across the year in lighting use. The load profile in Table 3-6 is adjusted by 

the multiplier for each month.

3.7 Appliances and Miscellaneous Electrical Loads

The electrical equipment in the house includes a refrigerator, clothes washer, clothes 

dryer, dishwasher, electric range, and a combination of variable miscellaneous electrical 

loads (MELs). MELs encompass electronics such as computers, televisions, stereos, and 

other plug loads. The electricity consumption for each category is based on the BA 

Protocol functions seen in Table 3-7. Electricity consumption is usually a function of the 

number of bedrooms in the home (NBR). The only category that will see an increase in 

electrical consumption over that of the one-story model is MELs because one variable in 

its function is square foot of conditioned floor area.

Table 3-7 Appliance and MEL Electricity Consumption

Equipment Function kWh

Refrigerator Constant 434

Clothes Washer 38.8+12.9*NBR 78

Clothes Dryer 538.2+179.4* NBR 1076

Dishwasher 87.6+29.2* NBR 175

Electric Range 250+83* NBR 499

Variable MELs 1703+ (266* NBR) + (0.454*CFA) 3502

Total: 5764

Source: Hendron and Engebrecht (2010)

The BA Protocol load profiles in Figure 3-6 create a real-time variation in electricity 

consumption for each category. Appliances such as the electric range and dishwasher 

have a significant variation in time-of-day use while refrigerator use varies only slightly 

over a day.
33

Figure 3-6 Electrical Equipment Load Profiles as a Proportion of Peak Wattage, By 

Hour of the Day

3.8 Internal Mass

Instead of defining individual interior surfaces and furniture, internal mass is estimated 

based on ASHRAE 90.2-2007 recommendations. There is assumed to be 3.6 kg (8 lb) of 

5 cm (2 in.) thick wood per square foot of conditioned space for a total of 8001 kg (17

640 lb). There is assumed to be 2.3 kg (5 lb) of 1.3 cm (0.5 in.) gypsum wall board 

(GWB) per square foot of conditioned space for the internal structure for a total of 

5001 kg (11 025 lb). 

EnergyPlus estimates internal mass in terms of square meters of material open to the zone 

air. Based on the total weight of the two materials (wood and GWB) and their weight per 

0.00

0.02

0.04

0.06

0.08

0.10

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Washer

0.00

0.02

0.04

0.06

0.08

0.10

0.12

1 3 5 7 9 11 13 15 17 19 21 23

Dishwasher

0.00

0.02

0.04

0.06

1 3 5 7 9 11 13 15 17 19 21 23

Refrigerator

0.00

0.02

0.04

0.06

0.08

0.10

1 3 5 7 9 11 13 15 17 19 21 23

Clothes Dryer

0.00

0.05

0.10

0.15

0.20

1 3 5 7 9 11 13 15 17 19 21 23

Range

0.00

0.02

0.04

0.06

0.08

1 3 5 7 9 11 13 15 17 19 21 23

MELs
34

unit of thickness, it is possible to determine the comparable surface area needed to match 

the amount of internal mass required. Assuming the wood density is equivalent to that of 

white oak, 753 kg per m3 (47 lb per ft3), the 5 cm (2 in.) thick wood weighs 38 kg per m

2

(7.833 lb per ft2) and would require 209 m

2 (2252 ft2

) of content mass. Assuming a 

density of 10 kg per m

2 (2.08 lb per ft2

) for GWB, a total of 492 m

2 (5300 ft2

) of 

structural mass is needed to meet the standard recommendations. 

3.9 Occupancy

Occupancy is based on the BA Protocol constant daily occupancy load profile seen in 

Table 3-8. The profile changes over the hours of the day, but does not vary across days. 

The house is treated as a single zone with an average internal heat gain of 113 watts per 

person (385.8 Btu/person/hr). The average number of people varies between all three 

family members being at home during the night to only 0.73 people present during the 

middle of the day.

Table 3-8 Occupancy Load Profile as a Proportion of Maximum Occupancy, and 

Total Occupants, By Hour of the Day

Hour Load Profile People Hour Load Profile People

1:00 1.000 3.00 13:00 0.242 0.73

2:00 1.000 3.00 14:00 0.242 0.73

3:00 1.000 3.00 15:00 0.242 0.73

4:00 1.000 3.00 16:00 0.242 0.73

5:00 1.000 3.00 17:00 0.295 0.89

6:00 1.000 3.00 18:00 0.553 1.66

7:00 1.000 3.00 19:00 0.897 2.69

8:00 0.883 2.65 20:00 0.897 2.69

9:00 0.409 1.23 21:00 0.897 2.69

10:00 0.242 0.73 22:00 1.000 3.00

11:00 0.242 0.73 23:00 1.000 3.00

12:00 0.242 0.73 24:00 1.000 3.00

3.10 Internal Heat Gains

Internal heat gains originate from domestic hot water use, electrical equipment use, 

lighting, and human occupancy. Previous sections have addressed specific internal heat 

gain categories, but it is of interest to summarize these heat gains and determine if they 

are comparable to the 2009 IECC standard reference design specifications. The total 

internal heat gains specified by 2009 IECC are based on the following equation. 

CFA NBR IGain =17900 + 23.8* + 4104*
35

Based on 2009 IECC, total internal heat gains, IGain, should be 24.2 kWh/day (82 691 

Btu/day) for the two-story prototype. The internal heat gains resulting from each category 

based on an EnergyPlus simulation of the prototype are shown in Table 3-9. The 

simulated internal heat gains of 20.4 (69 620 Btu/day) are lower than the 2009 IECC 

standard reference design (16 %). Although, the E+ model leads to slightly lower total 

heat gains than the 2009 IECC modeling assumption, the heat gains are based on more 

up-to-date assumptions.

Table 3-9 Heat Gain Comparison-Reference and Prototype Designs

Equipment BA Protocol

kWh (Btu)

2009 IECC 

kWh (Btu)

Prototype Design 

kWh (Btu)

Lighting NA NA 3.5 (11 806)

Equipment 12.9 (43 911) NA 11.3 (38 687)

Occupancy 5.6 (19 140) NA 5.6 (19 128)

Hot Water 1.2 (4161) NA 1.3 (4614)

Total NA 24.2 (82 691) 20.4 (69 620)
36
37

4 Recommendations for Future Research

Expansion of Current Prototypes. These one-story and two-story residential prototype 

designs are non-location specific and serve as a basis from which additional prototypes 

can be designed. Alterations to these two prototype designs should include selecting the 

location of the building, changing the square footage, changing the foundation type,

adding a garage, changing orientation, changing the heating fuel type, and designing to 

meet different editions of the IECC.

Location-Specific Factors. The prototype design is location neutral. For energy

simulation, each location requires its own weather file as well as specification of the 

following local parameters: location, ground temperature, water main temperature, and 

design days.27

Additional Building Sizes. Leaving the house dimension ratios the same at approximately 

2.56:1 and 1.60:1 for the 1-story and 2-story prototypes, respectively, the prototypes can

be expanded or contracted to meet the building sizes described in Table 4-1. 

Table 4-1 Additional Prototype Sizes

1-Story Prototypes 2-Story Prototypes

m2 (ft2) Dimensions

m (ft)

BR m2 (ft2) Dimension

m (ft)

BR

111.9 (1205) 6.61 x 16.89 

(21.67x55.42)

3 148.8 (1602) 6.8x10.9 

(22.37x35.8)

3

148.6 (1600) 7.62 x 19.51

(25.0x64.0)

3 204.9 (2205) 8.00 x 12.80

(26.25x42.0)

3

176.6 (1901) 8.31 x 21.26

(27.25x69.75)

3 251.2 (2704) 8.86 x 14.17

(29.07x46.5)

4

215.8 (2323) 9.17 x 23.53 

(30.1x77.21)

3 311.0 (3348) 9.85 x 15.78

(32.33x51.78)

4

292.8 (3152) 10.67 x 27.43

(35.0x90.0)

3 420.2 (4523) 11.49 x 18.29

(37.7x60.0)

4

These alternative building sizes are based on the U.S. Census’ Survey of Construction

database. Figure A-2 and Figure A-3 show the percentile breakdown of the size of new 

single-family detached houses for one-story and two-story houses, respectively, both in 

 27 An EnergyPlus database can be created with location-specific information readily available.
38

frequency (left y-axis) and cumulative distribution (right y-axis).

28 The building sizes 

selected for the additional residential prototype sizes represent the 10th, 30th, 50th, 70th, 

and 90th percentiles for each distribution.

The number of bedrooms by building square footage is displayed in Figure A-4 and

Figure A-5, for one-story and two-story houses, respectively. When designing additional 

prototypes, any one-story house with 316 m2 (3400 ft2

) or less of conditioned floor area 

can be assumed to have 3 bedrooms while any one-story house with greater than 316 m

2

(3400 ft2

) can be assumed to have 4 bedrooms. Any two-story house with 204 m

2

(2200 ft2) or less of conditioned floor area can be assumed to have 3 bedrooms while any 

two-story house with greater than 204 m

2 (2200 ft2

) can be assumed to have 4 bedrooms.

Additional Building Designs. The two prototype homes, oriented due south, can be 

altered in a number of ways to account for alternative building designs. First, a two-car 

garage can be added to various locations around the house (east, southeast, and 

southwest).

29 Second, the orientation of the house can be adjusted to have the front of the 

house facing due west, due east, southwest, and southeast. Since the house is designed 

symmetrically, these four additional orientations would represent the remaining 

orientations in 45 degree increments. Third, the slab-on-grade foundation is not the 

primary foundation type in some regions in the United States. Alternative foundation 

types can be added to the prototype designs to better represent the U.S. housing stock. 

The slab-on-grade can be replaced with a slab-in-grade foundation, a crawlspace, or a 

basement (finished and unfinished).

Heating Fuel Type. Although natural gas is the most common heating fuel source in the 

nation, particular regions of the nation, such as the South, tend to use electricity at least 

as often as natural gas. Also, a significant portion of the homes in the Northeast use fuel 

oil for heating. The prototype designs can be expanded to account for such heating fuel 

type changes.

Additional Energy Codes. The prototype residential buildings, designed to comply with 

2009 IECC, can be modified to meet older IECC codes -- 2000, 2003, and 2006 IECC--

to account for the variation in state energy codes across the United States as well as 2012 

IECC to account for future state energy code adoptions.

Parametric Designs beyond Current Code. Once prototypes for current state energy 

codes have been created, parametric improvements can be simulated to estimate energy 

savings from additional energy efficiency improvements using conventional approaches 

as well as emerging technologies.

 28 Homes with less than 700 ft2 are assumed to have 700 ft2

. 29 The most typical garage in the housing stock is an attached two-car garage.
39

References

American Society of Heating Refrigerating and Air-Conditioning Engineers, Inc., 2007, 

ANSI/ASHRAE Standard 62.2-2010, Ventilation and acceptable indoor air 

quality in low-rise residential buildings.

American Society of Heating Refrigerating and Air-Conditioning Engineers, Inc., 2007, 

ANI/ASHRAE Standard 90.2-2007, Energy-efficient design of low-rise 

residential buildings.

American Society of Heating Refrigerating and Air-Conditioning Engineers, Inc., 2009, 

ASHRAE handbook – fundamentals.

Department of Energy, 2012a, Building Energy Codes Program, Residential Prototype 

Building Models, 

http://www.energycodes.gov/development/residential/iecc_models/.

Department of Energy, Building Technologies Program, EnergyPlus energy simulation 

software, 2012b, http://apps1.eere.energy.gov/buildings/energyplus/.

Energy Information Administration, Commercial building energy consumption survey, 

http://www.eia.doe.gov/emeu/cbecs/.

Energy Information Administration, Residential energy consumption survey, 

http://www.eia.doe.gov/emeu/recs/.

Environmental Protection Agency, 2001, EPA Energy star home sealing specification.

Field, K., Deru, M., Studer, D., August 2010, Using DOE commercial reference building 

for simulation studies, Conference paper, presented at SimBuild 2010, NREL/CP550-48588.

Hendron, R., Engebrecht, C., January 2010, Building America research benchmark 

definition, National Renewable Energy Laboratory, Technical Report NREL/TP550-47246.

Hendron, R., Engebrecht, C., September 2010, Building America house simulation 

protocols, National Renewable Energy Laboratory, Building Technologies 

Program.

International Code Council, 2009, International residential code for one- and two-family 

dwellings.

International Code Council, 2009, International energy conservation code.
40

Lawrence Berkeley National Laboratory, accessed 2012, Useful conversion equations, 

http://epb.lbl.gov/blowerdoor/docs/conversions.pdf.

Pacific Northwest National Laboratory, September 2009, Impacts of the 2009 IECC for 

residential buildings at state level, Department of Energy Building Energy Codes 

Program.

Persily, A., Musser, A., Leber, D., August 2006, A collection of homes to represent the 

U.S. housing stock, National Institute of Standards and Technology, NISTIR 

7330.

RSMeans, 2005, Square foot costs – 27th annual edition, Reed construction data.

U.S. Census Bureau, National american housing survey, 

http://www.census.gov/hhes/www/housing/ahs/ahs.html.

U.S. Census Bureau, Manufacturing, Mining, and Construction Statistics Division, 2011, 

Annual 2010 characteristics of new housing, 

http://www.census.gov/const/www/charindex.html.
41

A Appendix

Figure A-1 ASHRAE Climate Zones by County
42

Figure A-2 Conditioned Floor Area of New 1-Story Single-Family Housing

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

Housing Units

Conditioned Floor Area - m^2 (ft^2)

Frequency

Cumulative %
43

Figure A-3 Conditioned Floor Area of New 2-Story Single-Family Housing

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000

Housing Units

Conditioned Floor Area - m^2 (ft^2)

Frequency

Cumulative %
44

Figure A-4 Conditioned Floor Area of New 1-Story Single-Family Housing by Number of Bedrooms

0

5000

10000

15000

20000

25000

30000

35000

Housing Units

Conditioned Floor Area - m^2 (ft^2)

2 Bedroom

3 Bedroom

4 Bedroom

5 Bedroom
45

Figure A-5 Conditioned Floor Area of New 2-Story Single-Family Housing by Number of Bedrooms

0

5000

10000

15000

20000

25000

Housing Units

Conditioned Floor Area - m^2 (ft^2)

2 Bedroom

3 Bedroom

4 Bedroom

5 Bedroom