Measured Whole-House 

Performance of TaC 

Studios Test Home

T. Butler, O. Curtis, and R. Stephenson

Southface Energy Institute

Partnership for Home Innovation (PHI)

December 2013
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iii

Measured Whole-House Performance of TaC Studios Test Home

Prepared for: 

The National Renewable Energy Laboratory

On behalf of the U.S. Department of Energy’s Building America Program

Office of Energy Efficiency and Renewable Energy

15013 Denver West Parkway

Golden, CO 80401

NREL Contract No. DE-AC36-08GO28308

Prepared by: 

T. Butler, O. Curtis, R. Stephenson

Southface Energy Institute

As part of the Partnership for Home Innovation (PHI)

400 Prince George’s Boulevard

Upper Marlboro, Maryland 20774

NREL Technical Monitor: Stacey Rothgeb

Prepared under Subcontract No. KNDJ-0-40335-00

December 2013
iv

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v

Contents

List of Figures ............................................................................................................................................ vi

List of Tables ............................................................................................................................................. vii

Definitions................................................................................................................................................. viii

Executive Summary................................................................................................................................... ix

Acknowledgements .................................................................................................................................... x

1 Introduction and Background ............................................................................................................. 1

1.1 Introduction..........................................................................................................................1

1.2 Background..........................................................................................................................1

1.3 Home Specifications............................................................................................................2

1.4 Research Questions..............................................................................................................4

1.5 Scope of Analysis ................................................................................................................5

2 Research Methods................................................................................................................................ 5

2.1 Energy Modeling .................................................................................................................5

2.2 Data Collection ....................................................................................................................6

2.3 Monitoring Period................................................................................................................7

3 Results................................................................................................................................................... 8

3.1 Whole House Energy Use....................................................................................................8

3.2 Energy Modeling Comparison...........................................................................................10

3.2.1 Comparison of Modeled and Actual Consumption ...............................................10

3.2.2 Comparison of BEopt 1.1 and 1.3 Outputs............................................................13

3.3 Ground Source Heat Pump ................................................................................................14

3.4 Desuperheater (DSH).........................................................................................................19

3.5 Ventilation..........................................................................................................................20

4 Discussion........................................................................................................................................... 23

5 Conclusion .......................................................................................................................................... 24

References................................................................................................................................................. 26

6 Appendices ......................................................................................................................................... 27

Appendix A: Monitoring Diagrams.........................................................................................27

Appendix B: Project Map and Location ..................................................................................29
vi

List of Figures

Figure 1. TaC Studios residence. .............................................................................................................. 2

Figure 2. TaC Studios residence HVAC zoning diagram. ....................................................................... 4

Figure 3. Source energy savings for TaC Studios compared to the B10 Benchmark, BEoptE+ v1.1.5

Figure 4. Source energy savings for TaC Studios compared to the B10 Benchmark, BEoptE+ v1.3.6

Figure 5. Whole house energy consumption, January 15 to July 15, 2012. ......................................... 8

Figure 6. February whole house end-use electric consumption. .......................................................... 9

Figure 7. Actual versus TMY3 weather data........................................................................................... 10

Figure 8. Whole house energy consumption, typical end uses versus modeled outputs. ............... 11

Figure 9. Whole house energy consumption, measured component end uses................................. 12

Figure 10. HVAC energy consumption comparison between TMY3, AMY, and actual usage. ......... 12

Figure 11. Comparison between GSHP and high efficiency ASHP...................................................... 13

Figure 12. GSHP measured efficiency. ................................................................................................... 16

Figure 13. GSHP run time and incoming loop temperatures................................................................ 17

Figure 14. House performance, June 30................................................................................................. 18

Figure 15. HVAC System draw profile..................................................................................................... 19

Figure 16. DSH influence on DHW tank temperature. ........................................................................... 20

Figure 17. Ventilation control settings.................................................................................................... 21

Figure 18. HVAC system operation, March 2012. .................................................................................. 22

Figure 19. System fractional on time. ..................................................................................................... 23

Figure 20. Monitoring diagram. ............................................................................................................... 27

Figure 21. TaC Studios residence location. Credit: Map Data © 2012 Google, Sanborn................... 29

Unless otherwise noted, all figures were created by Southface.
vii

List of Tables

Table 1. TaC Studios Residence Building Specifications....................................................................... 2

Table 2. Test and Monitoring Parameter Description.............................................................................. 6

Table 3. Georgia Power Seasonal Base Rates......................................................................................... 9

Table 4. HDDs and CDDs, Actual Versus TMY3 for Atlanta.................................................................. 10

Table 5. List of Monitoring Equipment.................................................................................................... 28

Unless otherwise noted, all tables were created by Southface.
viii

Definitions

ACCA Air Conditioning Contractors of America

ACH50 Air changes per hour at 50 Pascals, infiltration measurement

AHRI Air-conditioning, Heating, and Refrigeration Institute

AMY Actual meteorological year

ASHP Air-source heat pump

BEopt Building energy optimization software

CFIS Central fan integrated supply, ventilation method

CFL Compact fluorescent lamp

CFM Cubic feet per minute, air flow volume measurement

COP Coefficient of performance, heating efficiency

DSH Desuperheater

EER Energy efficiency ratio, cooling efficiency

GSHP Ground-source heat pump

HSPF Heating seasonal performance factor, heating efficiency

HVAC Heating, ventilation, and air conditioning

kW Kilowatt, power measurement

kWh Kilowatt hour, energy measurement

LFL Linear fluorescent lamps

NREL National Renewable Energy Laboratory

SEER Seasonal energy efficiency ratio, cooling efficiency

SLA Specific leakage area, infiltration measurement

TMY Typical meteorological year
ix

Executive Summary

As part of the Partnership for Home Innovation (PHI), Southface partnered with TaC Studios, an 

Atlanta-based architecture firm specializing in residential and light commercial design, on the 

construction of a new test home in Atlanta, Georgia, in the mixed-humid climate zone. This 

home serves as a residence and home office for the firm’s owners, as well as a demonstration of 

their design approach to potential and current clients. Southface believes the home demonstrates 

current best practices for the mixed-humid climate, including a building envelope featuring 

advanced air sealing details and low density spray foam insulation, glazing that exceeds 

ENERGY STAR® requirements, and a high performance heating and cooling system. 

Construction quality and execution was a high priority for TaC Studios and was ensured by a

third-party review process through the project’s involvement in the LEED for Homes program.

Post-construction testing showed that the project met stated goals for envelope performance, an 

air infiltration rate of 2.15 ACH50. The homeowners wished to further validate whole house 

energy savings through the project’s involvement with Building America and this long-term 

monitoring effort. As a Building America test home, this home was evaluated to detail whole 

house energy use, end use loads, and the efficiency and operation of the ground source heat 

pump (GSHP) and associated systems. Given that the home includes many non-typical end use 

loads including a home office, pool, landscape water feature, and other luxury features not 

accounted for in Building America modeling tools, these end uses were separately monitored to 

determine their impact on overall energy consumption.

The home has been occupied since completion in September 2011. Short-term characterization 

testing was completed in October 2011, with long-term monitoring equipment installed in 

December 2011. This report includes analysis of the data collected through this effort, focusing 

on the six-month period from January 15 to July 15, 2012.

Monitored data for whole house energy consumption showed that the home exceeds projected 

energy consumption from Building America modeling tools, using roughly twice the energy 

expected; however, with the non-typical loads removed from the whole house total, the actual 

energy use is much more in line with BEopt outputs. The non-typical loads account for 48% of 

total energy consumption over the monitored period, with the pump associated with a landscape 

water feature making up three quarters of total non-typical use. Removing these non-typical 

loads results in consumption within 21% of weather-normalized BEopt projections. A closer 

examination of the data revealed that HVAC energy use exceeding modeled projections was 

primarily responsible for the difference in modeled and actual consumption. 

Southface has found that GSHPs have considerable cachet value in the local residential market, 

and the question of real versus perceived value was a major research focus for this project. The 

research results showed measured efficiency values that fell below rated and manufacturer’s 

published data, finding an average cooling efficiency of 14.3 energy efficiency ratio (EER) for 

the monitoring period. This measured efficiency does not greatly exceed the efficiency provided 

by currently available high efficiency air-source heat pump options, making the recommendation 

of GSHPs over more traditional options a hard sell on cost effectiveness alone. However, the 

long-term monitoring effort did reveal that the GSHP in this home may have insufficient loop 
x

sizing to provide adequate ground heat exchange and other installation issues that contributed to 

this drop in performance. These findings and other issues with the home’s HVAC and ventilation 

controls show that HVAC system design and installation best practices should remain focus 

areas for Building America.

This long-term monitoring effort will continue through early 2013, and Southface hopes to take 

that opportunity to determine measured heating efficiency for the home’s GSHP, providing 

additional information on the cost effectiveness of these systems. Southface will also assist the 

homeowners with recommendations to reduce whole house energy consumption, particularly 

from the large loads associated with the home’s pool and landscape water feature. The LEED 

Silver certified home continues to serve as a demonstration project for TaC Studios, Southface, 

and the Building America program, and has been featured in multiple home tours, regional 

conferences, and local newspaper articles.

Acknowledgements

Southface would like to thank Dr. Russell Gentry, and James Veldhorst of the Georgia Institute 

of Technology for their assistance with equipment set-up and data collection.
1

1 Introduction and Background

1.1 Introduction

Space conditioning represents the largest portion of residential energy consumption and has been 

a primary target for achieving substantial use reductions. Regarded as one of the most efficient 

system choices, ground source heat pumps (GSHPs) incorporate complex components and 

extensive infrastructures to reduce the impact of fluctuating ambient conditions for heat 

exchange and rely on sophisticated controls strategies to extract efficiency out of part-load 

conditions. Research and testing have documented efficiencies that exceed standard efficiency 

conventional air-to-air systems (Puttagunta & Shapiro, 2012), but in the case of this home, a 

GSHP system came at more than double the initial cost of high efficiency conventional systems. 

When this cost premium is considered along with the lowered space conditioning loads of high 

performance homes and the capabilities of the typical HVAC contractor to size, install and 

commission a GSHP, the question of cost effectiveness becomes a major issue in the choice of 

this technology over high efficiency traditional systems or emerging technologies such as 

variable refrigerant flow split systems. 

Currently, the market has demonstrated that the high price, technological complexity, available 

tax incentives, and acoustic/aesthetic benefits of GSHPs from the elimination of exterior 

condensers have given the system a cachet value in the high-end residential market, similar to 

marquee kitchen appliances and luxury automobiles. As with more traditional durable consumer 

goods, an appreciable improvement in performance and comfort may be seen; however, given

the less tangible and more personal factors associated with thermal comfort and indoor air 

quality, it remains to be seen if these improvements represent real value to overall home energy 

efficiency.

This test home provided the opportunity to gather real world performance data for a GSHP 

system, and the primary research focus of this study is the evaluation of the GSHP performance 

against rated efficiency values and previous studies. Monitoring equipment installed in the home 

gathered the data necessary to complete this evaluation, as well as whole house energy use and 

the isolation of non-typical loads found in this home including a home office, pool, landscape 

water feature, and other luxury features not accounted for in Building America modeling tools. 

The long-term monitoring results provided data to address the question of real versus perceived 

value.

1.2 Background 

As part of the Partnership for Home Innovation (PHI), Southface partnered with TaC Studios, an 

Atlanta-based architecture firm specializing in residential and light commercial design, on the 

construction of a new Building America test home in Atlanta, Georgia, in the mixed-humid 

climate. This home serves as a residence and home office for the firm’s owners, as well as a 

demonstration of their design approach to potential and current clients.

The three-story design has 3,570 ft2 of conditioned floor area over a sealed crawlspace 

foundation. The first floor includes the kitchen, dining, and living areas with a half bath and an 

attached garage (564 ft2

). The second floor includes two bedrooms, a library, three full baths, and 

a home office that has the flexibility to function as two bedrooms at a future date. The third floor 
2

includes a small entertaining space with access to a roof top deck. Ceilings are 10 ft at the first 

floor and 9 ft at the second floor. The third floor ceiling is sloped. The home’s modern 

architecture includes many unique overhang and cantilevered details that required special 

attention in the air sealing and insulation design, and installation. Luxury features that are not 

included in the Building America Benchmark include a pool, landscaping water feature, electric 

radiant floor heat, home office, and an all-electric gourmet kitchen. 

Figure 1. TaC Studios residence.

The home has been occupied since the completion of construction in September 2011. Shortterm characterization testing and system commissioning was completed in October 2011, with 

long-term monitoring equipment installed in December 2011. 

1.3 Home Specifications

This home incorporated features to improve the overall thermal performance of the building 

envelope, provide high performance space conditioning and domestic hot water (DHW) delivery,

and bring mechanical components within conditioned space. Table 1 lists the building 

specifications for the home, with further detail provided on the home’s HVAC system below. 

Building America 2010 Benchmark specifications have been included for reference.

Table 1. TaC Studios Residence Building Specifications.

Measure B10 Benchmark TaC Studios Residence

Foundation Sealed Crawlspace Sealed Crawlspace

Foundation Insulation R-5 R-7, continuous open cell 

spray foam, interior

Wall Construction 2×4 2×6

Wall Insulation R-13 R-13, partial fill open cell 

spray foam

Ceiling Construction Vented Attic Cathedral attic, with flat 

roof trusses

Ceiling Insulation R-30 R-20 open cell spray foam 

to underside of sheathing

Cantilever Floor R-30 R-19, open cell spray foam 
3

Insulation to underside of sheathing

with floor trusses

Window Ratings U-0.40, SHGC-0.30 Varies:

U-0.34, SHGC-0.26 max

U-0.28, SHGC-0.19 min

Infiltration 6.6 ACH50 2.5ACH50

Heating Efficiency 7.7 HSPF 3.9 COP

Cooling Efficiency 13 SEER 18 EER

Supply Duct Location 65% crawlspace, 35% 

conditioned space

50% crawlspace, 50% 

conditioned space

Return Duct Location 100% crawlspace 50% conditioned space, 

50% crawlspace

Duct Leakage 15% total < 15% total

Ventilation Exhaust 100% ASHRAE 

62.2

Central fan integrated 

supply, 100% ASHRAE 

62.2

Hot Water Efficiency 0.86 EF, electric 0.92 EF, electric (DSH)

Lighting 66% incandescent,

21% CFL,

13% LFL

100% incandescent w/ 

automated dimming

Appliances Benchmark Induction cooktop, 

ENERGY STAR

The primary system investigation in this home includes researching the HVAC system. The 

GSHP included in this project presents an opportunity to evaluate the cost effectiveness and infield efficiency of this technology in a ground loop application. Per AHRI/ISO 13256, this dual 

stage GSHP is rated at 18.0 EER and 3.9 COP at full load with full load cooling and heating 

capacities of 67.6 kBtuh and 45.8 kBtuh, respectively. At part load, it is rated at 25.6 EER and 

4.2 COP, with 51.1 kBtuh and 36 kBtuh of heating and cooling capacity respectively. The unit 

also includes a desuperheater (DSH) to provide water pre-heating. The ground exchange loop for 

the system includes five 250 ft deep vertical wells. The home was designed with four separate 

HVAC zones, shown in Figure 2, all served by this single unit. Characterizing the operation of 

the unit during part load conditions, when a single zone calls for conditioned air for example, 

was a research priority for this study. 
4

Figure 2. TaC Studios residence HVAC zoning diagram.

Meeting ASHRAE 62.2 ventilation rates introduces another tradeoff choice to builders in the 

mixed-humid climate zone. Builders want to meet the air flow requirements in the most costeffective manner, while choosing a system that mitigates the added costs and latent loads that are 

introduced by ventilation air. Southface has observed that the most prevalent ventilation strategy 

in the local market is the central fan integrated supply (CFIS). This strategy consists of a ducted 

outside air intake connected directly to the return plenum of the central HVAC system. The 

negative pressure of the return pulls ventilation air through the intake and the air is distributed 

throughout the home using the supply fan and ductwork of the central system. The intake duct 

includes a mechanical damper equipped with a ventilation timer allowing for variable amounts of 

outside air to be introduced into the central system. This timer ensures adequate ventilation on 

mild days when the central system is not calling for heating or cooling by opening the damper 

and calling on the central fan to run.

Monitoring the additional system run time linked to the CFIS controller will provide further data 

regarding the energy costs and effectiveness of this ventilation approach. Southface hopes to 

build upon the past Building America ventilation studies by focusing on the additional fan 

energy consumption associated with this ventilation strategy.

1.4 Research Questions

The data gathered from this new construction test home will be used to address the following 

research questions:

• Is the measured energy use for heating and cooling consistent with modeled estimates,

given similar ambient weather conditions?

• How does the efficiency of the GSHP compare to AHRI ratings and manufacturer’s 

published data?

• Is “rule of thumb” loop sizing adequate for this application? 

• What is the additional fan energy associated with the CFIS ventilation system?
5

1.5 Scope of Analysis

This report reviews the results of the long-term monitoring effort for this test home. Whole house 

energy consumption and HVAC energy consumption will be compared to modeled results from 

BEopt energy modeling software using actual weather conditions. The efficiency and operational 

characteristics of the home’s GSHP will be examined in greater detail, comparing monitored 

results to manufacturer’s data and past research studies. Also, the ability of the home’s 

ventilation system to meet ASHRAE 62.2 ventilation requirements will be determined, as well as 

the fan energy consumption associated with the system.

2 Research Methods

2.1 Energy Modeling

Southface completed energy simulations and cost tradeoff analysis for this project using the 

BEopt energy optimization tool, BEoptE+ version 1.1. Several assumptions were made for this 

analysis based on gaps in the available BEopt inputs. Without an input option to accurately

capture the functionality of the home’s lighting system, the final design was simulated using the 

B10 Benchmark lighting package. Similarly, BEoptE+ version 1.1 does not include option for

the GSHP or DSH included in this project. In lieu of these options, the most efficient air-source 

heat pump (ASHP) and electric storage tank options were chosen for the simulation, 18 SEER, 

9.2 HSPF and 0.95 EF respectively. This analysis showed a 30.7% whole house source energy 

savings with respect to the Building America B10 Benchmark (BAB in Figure 3).

Figure 3. Source energy savings for TaC Studios compared to the B10 Benchmark, BEoptE+ v1.1.

Following the end of construction, Southface completed additional energy modeling using an 

updated version of BEopt, BEoptE+ version 1.3, which includes options for GSHPs. This 

analysis showed a drastically different result, a 15.8% whole house source energy savings with 

respect to the Building America B10 Benchmark. Possible explanations for this discrepancy are 

discussed later in this report.
6

Figure 4. Source energy savings for TaC Studios compared to the B10 Benchmark, BEoptE+ v1.3.

2.2 Data Collection

The technical approach for this research home included short-term testing to verify the whole 

house infiltration rates and commissioning of the mechanical systems to ensure the system’s 

operation and performance meets design parameters. The long-term monitoring effort collected

whole house and end use electric consumption data, as well as measurements necessary to 

determine efficiency, capacity, and operation characteristics of the GSHP and hot water systems. 

Table 2 covers a brief description of the test methods employed and purposes.

A monitoring layout for the home is detailed in Appendix A.

Table 2. Test and Monitoring Parameter Description.

Parameter of 

Interest

Test Method Purpose

House infiltration 

rate

Blower door test and 

diagnostic evaluation

At construction completion – provide overall 

infiltration rate and locate remaining major 

leakage paths

HVAC duct 

tightness and 

overall duct system 

performance 

Duct leakage test; Air 

handler and diffuser 

flow rates; Room 

pressure differentials

(air handler running, 

doors closed); total 

external static pressure

At construction completion – characterize 

overall air delivery system

Ventilation system 

performance

Balometer 

measurements

At construction completion – measure supply 

ventilation air flow rate and exhaust fan flow 

rates. Measure house depressurization during 

exhaust fan operation
7

Parameter of 

Interest

Test Method Purpose

Whole house 

electric

Power Monitoring Record whole house electricity use

End use loads Power Monitoring Record end use electricity consumption for;

Lighting, Home office, Refrigerator, Induction 

Cooktop, Oven, and Steam Oven

Identify demand profiles

Space conditioning 

and hot water 

equipment

Power Monitoring, 

Ground Loop and 

DHW Conditions 

Monitoring

Document the operation of the HVAC system 

relative to interior setpoints and exterior 

ambient drivers

Document the real time efficiency of the 

HVAC system

Document the added run time attributed to the 

CFIS ventilation system

Document the operation of the water heater 

system relative to resident demand 

Document the contribution of the DSH to the 

hot water load

Indoor 

Environment

Temperature/Relative 

Humidity (RH) 

measurements

Analyze the operation of the HVAC system 

relative to interior and exterior temperature 

and humidity drives

2.3 Monitoring Period 

The long-term monitoring effort began in December 2011 and continues to the present. The 

installation of this many data points presented challenges that had to be overcome by the 

Southface research team. Using Modbus-RTU as the communications protocol to the logger 

allowed for the connection of various recording devices, but the programming of the Trendpoint 

consumption registers presented issues, as problems with scaling and the bit size of the registers 

led to the counters resetting. The researchers overcame this issue by calculating consumption 

from the power draw readings. 

The loop temperature measurements posed a greater challenge. Initial measurements showed the 

change in incoming and outgoing loop temperatures did not return realistic values, with the 

incoming loop temperatures measured at unusually high levels. The thermocouple calibration 

was checked and found to be acceptable. After reviewing the newly released Building America 

Field Test Best Practices website, Southface determined that the loop temperature sensor was not 

seeing appropriate flow. Longer probes were installed facing directly into the flow of both loops, 

providing better measurements. Unfortunately, the heating season had passed before reaching 

this solution, and valid measurements were not available to derive COP performance with water 

side calculations. An air-side performance value could be determined using the other collected 

data, but determining correct airflow volume from power readings given the multiple zones of 

the system presents additional challenges. This report includes analysis of the data collected 

through this effort focusing on the six-month period from January 15 to July 15, 2012. 
8

Monitoring will continue through early 2013, providing an opportunity to determine water side 

COP values.

3 Results

3.1 Whole House Energy Use

Given that the home functions as the primary workspace for the owner/architects and features 

several non-typical end uses loads including a home office, pool, landscape water feature, and 

other luxury features not accounted for in Building America modeling tools, the monitoring of 

power consumption at the circuit breaker level was determined to be necessary to validate whole 

house usage against the modeled results. Usage for appliances not found in a typical residential 

kitchen (i.e., a steam oven, ice maker, and wine refrigerator) and electric radiant floor heating 

have been labeled as “luxury” loads. The pumps associated with the pool and a landscape water 

feature have been labeled as “outside” loads. The home office has also been separately 

monitored and labeled “home office” load. Figure 5 shows whole house energy consumption for 

the six-month period from January 15 to July 15, 2012 broken down by end use.

Figure 5. Whole house energy consumption, January 15 to July 15, 2012.

This end-use monitoring brought to light how energy intensive the pool and pond are in relation 

to the whole house end use, representing approximately 34% of total consumption over the 

monitoring period. Total consumption for the non-typical loads—luxury, outside, and home 

office—accounted for 48% of total consumption. 

The monitoring data also revealed that all end uses are fairly consistent from month to month 

except for the HVAC and the luxury loads. While the change in HVAC makes sense based on 

fluctuations in weather, a closer look at energy consumption for February 2012 in Figure 6, the 

month with the highest luxury load consumption, shows that the major contributor to this 

0

20

40

60

80

100

120

140

160

180

200

1/15/12 2/15/12 3/15/12 4/15/12 5/15/12 6/15/12

kWh

Whole House Energy Consumption

Unmonitored Kitchen Laundry DHW HVAC Home Office Outside Luxury
9

consumption is electric radiant floor heating. In April, this load is less than half the February 

total, and it goes away completely in May. The other loads in this group stay fairly consistent. 

Figure 6. February whole house end-use electric consumption.

The large whole house energy consumption, approximately 3,600 kWh per month over the 

monitoring period, leads to excessive energy bills in the summer months. The homeowner 

contacted Southface complaining of a huge jump in electric utility bills in the summer of 2012. 

Examination of the consumption data did not show a corresponding rise in total consumption, 

but a closer look at the tiered rate structure used by Georgia Power, Table 3, revealed the cause. 

A home at this consumption level pays $0.10/kWh in the winter, spring and fall, but that rate 

jumps to nearly $0.17/kWh in the summer months, with more than half of these rates going to 

fees, fuel recovery, and taxes. 

Table 3. Georgia Power Seasonal Base Rates.

Tier Usage (kWh) Winter Summer % Increase

1st tier up to 650 $0.052465 $0.052465 0.0%

2nd tier next 350 $0.045015 $0.087211 93.7%

3rd tier over 1000 $0.044190 $0.090126 104.0%
10

3.2 Energy Modeling Comparison

3.2.1 Comparison of Modeled and Actual Consumption

Before comparing model projections to actual monitored data, Southface updated the energy 

model using Actual Meteorological Year (AMY) weather data. Table 4 compares the cooling and 

heating degrees days for the AMY data and the Typical Meteorological Year 3 (TMY3) file used 

for the initial modeling. TMY3 data sets are a compilation of hourly weather data for a specific 

geographical location usually based on a 30-year time period (Wilcox & Marion, 2008). This 

weather profile is then used in building simulations to predict climate specific performance. 

Figure 7. Actual versus TMY3 weather data.

The results summarized in Table 4 show a significantly milder winter heating season and a 

warmer summer cooling season than is typical for Atlanta. Although TMY3 data should not be 

used to predict actual weather in any location, it is useful as a possible explanation for large 

variations in predicted versus actual HVAC energy performance. 

Table 4. HDDs and CDDs, Actual Versus TMY3 for Atlanta

Actual September 2011 to 

August 2011 Degree Days 

(reference here)

TMY3 File Degree 

Days

% Difference of 

Actual to TMY3

HDDs 2478 2826 -12.3%

CDDs 1955 1722 13.5%

In order to create a valid comparison between the modeled and actual results, Southface 

individually metered non-typical end uses loads including a home office, pool, koi pond, and 

other luxury features not accounted for in Building America modeling tools. Removing these end 

uses from the monitored consumption data allows for a comparison between actual and modeled 

energy consumption. Figure 8 compares the actual “typical” energy usage to the predicted total 

energy consumption based on the BEopt model with AMY weather data. It should be noted that 

removing the non-typical end uses from whole house energy consumption does not remove any 

0

100

200

300

400

500

600

700

800

900

Degree Days (65F)

Actual vs. TMY3 Weather Data

TMY3 HDD Actual HDD TMY3 CDD Actual CDD
11

internal gains or other effects on the home’s HVAC energy use. Measured typical energy use 

showed 21% greater energy use than weather normalized modeled projections.

Figure 8. Whole house energy consumption, typical end uses versus modeled outputs.

The data shows excellent agreement for the monitoring period from January 15, to March 15,

before unknown, non-weather related increases in the HVAC consumption cause the measured 

energy consumption to spike. Analyzing the component end use data further, as shown in Figure 

9, showed that the HVAC system appeared to be constantly operating for several days at a time

in mid-March. Given that the house has a large amount of east-facing glass, these discrepancies 

may be driven by solar gain. The system run profiles shown in Figure 14 indicate a high 

frequency of run cycles early in the morning, despite ambient temperatures being below the 

maintained set-point. 

0

20

40

60

80

100

120

1/15/12 2/15/12 3/15/12 4/15/12 5/15/12 6/15/12

kWh

Whole House Energy Consumption

Measured "Typical" Beopt Output, Weather Normalized
12

Figure 9. Whole house energy consumption, measured component end uses.

Figure 10 demonstrates that weather normalizing the BEopt model AMY data inputs shows a 

stronger correlation to monitored HVAC usage when the actual weather varies significantly from 

the TMY3 file. 

Figure 10. HVAC energy consumption comparison between TMY3, AMY, and actual usage.

0

10

20

30

40

50

60

70

80

3/1/12 3/6/12 3/11/12 3/16/12 3/21/12 3/26/12 3/31/12

kWh

Whole House Energy Consumption

Unmonitored Kitchen Laundry HVAC

Home Office Outside Luxury

0

200

400

600

800

1000

1200

2/1/2012 3/1/2012 4/1/2012 5/1/2012 6/1/2012

kWh

Modeled versus Actual HVAC Energy Consumption

TMY3 (modeled) AMY (modeled) Actual
13

3.2.2 Comparison of BEopt 1.1 and 1.3 Outputs

As previously discussed, differences in the outputs of BEopt v.1.1 and v.1.3 drastically reduced 

the projected source energy savings for this home. The BEopt development team at NREL 

related that this decrease from 30.7% to 15.8% source energy savings can be traced to changes in 

the natural ventilation rates, HVAC sizing procedure, and dehumidification loads used by the 

program. 

The initial optimization analysis for TaC Studios was conducted in BEopt v.1.1, an early 

software release. This version did not have the capability to model GSHPs, a critical energy 

saving component of the TaC Studios design. As a result, the initial optimization analysis 

substituted the highest efficiency library input ASHP (18 SEER, 9.3 HSPF) to simulate the 

predicted energy performance of the GSHP. The most current release, BEopt v.1.3, incorporates 

GSHPs into the options library; therefore, the model was updated to reflect the actual system 

type. Southface selected a default option, 18.2 EER and 3.7 COP with low-k soil GSHP, instead 

of creating a custom library because certain installation performance characteristics were not 

known, such as loop pipe diameters, grout type, and on-site soil conductivity. Southface 

conservatively assumed low soil conductivity and standard grout. 

Figure 11 shows the results, a 3.6% increase in total source energy use, of the comparison 

between the GSHP and high efficiency ASHP. 

Figure 11. Comparison between GSHP and high efficiency ASHP.

The GSHP option shows lower heating energy use and marginally higher cooling energy use 

than the ASHP; however, the reductions do not offset the increased pump energy required to 

operate the GSHP.
14

3.3 Ground Source Heat Pump

The primary research focus for this study was the evaluation of the home’s GSHP and comparing 

in-field performance against rated efficiency values and the results of previous studies. Southface 

has found that homeowners and builders select GSHP systems due to perceived increased 

efficiency and the lack of exposed external equipment outside the home, improving aesthetics 

and reducing noise. The question becomes whether the efficiency and additional aesthetic and 

comfort factors associated with these systems offsets their higher initial installation cost. Similar 

to a conventional air-source heat pump, this cost is a factor of the air handler and associated 

ducting and controls, as well as the costs for installing the heat exchange loop. For the TaC

Studios residence, the loop is a series of five vertical bore wells. The monitoring effort measures 

overall system power use, electric use for individual system components (compressor, fan, loop 

pump and DSH pump), loop flow, and temperatures for the ground loop and the DSH. Air 

temperature and humidity in the supply, return and outside air ducts are also monitored.

The data points are used to calculate system efficiencies for heating and cooling using the 

following formulas.

Heating Coefficient of Performance:

( )

W W W W Btu/Wh

Q W W W Btu/Wh

net energy input

useful heating energy COP

comp fan pump DHW pump

h fan comp DHW pump

( ) 3.413

3.413

,

,

+ + + ×

+ + + × = =

(1)

where:

COP = coefficient of performance of the complete system [dimensionless]

Qh = useful heat extracted from loop [Btu]

Wcomp = energy consumed by the compressor [Wh]

Wfan = energy consumed by the fan [Wh]

Wpump = energy consumed by the loop pump [Wh]

WDHW,pump = energy consumed by DSH pump [Wh]

Heat extracted from the ground loop:





 



 = ∆ × × × •

Qh TT −T V Cp ρ in out (2)

where:

Tin Tout ∆T − = Tin minus Tout (°F) •

V = volumetric loop flow rate [ft3/hr]

Cp = specific heat of loop fluid [Btu/lbm°F]

ρ = density of loop fluid [lb/ft3]
15

Cooling Energy Efficiency Ratio

( )

( )

3.413 Btu/Wh

net energy input

useful cooling energy

comp fan pump DSH , pump

c DSH fan comp

W W W W

Q Q W W

EER

+ + +

+ − + × = =

(3)

where:

EER = energy efficiency ratio [Btu/Wh]

Qc = heat dumped to loop [Btu]

QDSH = heat transferred to DWH by desuperheater [Btu]

Wcomp = energy consumed by the compressor [Wh]

Wfan = energy consumed by the fan [Wh]

Wpump = energy consumed by the loop pump [Wh]

WDSH,pump = energy consumed by the desuperheater pump [Wh]

As noted earlier, there were issues in obtaining accurate loop temperatures during the heating 

season that made the calculation of COP impossible. Cooling performance measurements 

showed that the system is performing below the rated and manufacturer’s published efficiencies;

see Figure 12. From previous research, this discrepancy is to be expected given that the rated 

conditions do not account for pump energy or increased static pressure from a full duct system

(Puttagunta, Aldrich, Owens, & Mantha, 2010). Looking at one week of data with a broad range 

of temperature conditions reveals a slight increase in the difference between rated and actual 

performance as the loop temperatures decrease. The overall average EER for this period is 14.3 

at an average loop temp of 77.5oF. These results indicate a 20% reduction from the rated 

efficiency and are consistent with a similar study (Puttagunta and Shapiro, 2012), which found a 

23% lower measured efficiency from the rated performance.
16

Figure 12. GSHP measured efficiency.

Southface believes inadequate ground loop capacity may be partly responsible for this drop in 

efficiency, as the incoming loop temps, which are measured after the heat exchange fluid has 

circulated completely through the loop, show large temperature rises during system run time. 

The loop temp fluctuations are influenced by the run time of the system (Figure 13). This 

reduction in performance over time suggests that the loop design could have benefited from a 

more thorough analysis in the design stage. The vertical bores for this project were based on 

basic rule of thumb assumptions and no soil analysis was completed. While the cost of this 

design work is greater, the fact that the loop is essentially a permanent component of the system 

may make this cost worthwhile. Controlling the thermal envelope and internal gains will have an 

indirect impact on the overall performance of the system by reducing the amount of time a

system runs.

0

5

10

15

20

25

60 65 70 75 80 85 90 95

EER

Incoming Loop Temperature Deg F

EER at Loop Temp

AHRI EER Actual EER Manufacturer EER
17

Figure 13. GSHP run time and incoming loop temperatures.

This also points to an issue of system run time, which is influenced by the zoning of the system. 

Looking at the hottest day of the summer, June 30 (shown in Figure 14), when ambient 

temperatures greatly exceeded design conditions for a significant portion of the day, it would be 

expected that a properly sized system would run continuously to keep up with the load, but the 

system short cycled throughout the day with an average run time of 12 minutes.

0

2

4

6

8

10

12

14

16

0

10

20

30

40

50

60

70

80

90

12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM12:00 AM

Temperature degF

Run time and Loop Temp

loop_temp_in_f loop_flow
18

Figure 14. House performance, June 30.

As shown in Figure 2, the house is divided into four distinct zones of varying sizes and 

orientations. Each zone has a programmable thermostat set to provide conditioning when that 

zone is most typically occupied; early morning and evening for the main floor, daytime for the 

office zone and night for the master bedroom. The guest room zone is rarely used and typically 

not directly conditioned. The system was sized using ACCA Manual J and took into account the 

increased air sealing and improved glazing values over conventional, code minimum values, but 

it is not apparent if the zoning was factored in the design. Essentially, a system designed for a 

3,500 ft2 house is being operated to meet loads for significantly smaller areas, which most likely 

leads to the short cycling indicated in Figure 14. This data also indicated very little difference in 

power consumption between low and high stage operation. Figure 15 shows the individual 

component loads from a longer run event that displays a brief period of low stage operation,

from 6:00 to 6:03 PM, then full compressor operation with fluctuations in fan speed. From this, it 

appears that the staging is minimally effective in dealing with part load conditions. 

0

20

40

60

80

100

120

0

2

4

6

8

10

12

14

16

6:00 8:00 10:00 12:00 14:00 16:00 18:00

Electric Load, kW

Temperature dgeF

HVAC and Total House Load 

HVAC Load House Load Ext Temp Int Temp (F)
19

Figure 15. HVAC System draw profile.

3.4 Desuperheater (DSH)

The DSH operation was not initiated until September 2012, after the monitoring period covered 

in this report. Initial data gathered from early September, shown in Figure 16, suggests that there 

is an issue in which the operation of the DSH may be lowering the temperature of the water in 

the water heater tank. It is not clear if this is due to a change in temperature settings by the owner 

or if the DSH is truly reducing the temperature of the stored hot water. Comparing power draw 

of the DHW tank element to the tank and DSH loop temperatures suggests that the tank 

temperature settings have been altered. As monitoring continues, this will be studied further.

0

500

1000

1500

2000

2500

3000

3500

4000

6:00 PM 6:04 PM 6:09 PM 6:14 PM 6:19 PM 6:24 PM 6:29 PM

Demand (w)

System Draw Profile

dshpump_demand fan_demand loop_demand

compressor_demand Total System
20

Figure 16. DSH influence on DHW tank temperature.

3.5 Ventilation

Building America has identified the development of ventilation best practices as a critical path 

milestone on the path towards achieving 50% whole house energy savings (NREL, 2012). 

Southface has observed that the prevalent strategy used to meet the ventilation flow and controls 

requirements of ASHRAE Standard 62.2 in the local market is the CFIS, the approach 

implemented in this test home. In order to evaluate the viability and energy impacts of this 

system choice, Southface completed system commissioning to ensure the system had adequate 

flow to meet Standard ASHRAE 62.2 requirements and installed long-term monitoring 

equipment to track the additional run time and energy consumption of the air handler fan.

The ASHRAE 62.2 ventilation standard sets a minimum continuous ventilation rate based on a 

home’s conditioned floor area and number of bedrooms.

Qfan = 0.01Afloor + 7.5(Nbr + 1) (4)

where

Qfan = fan flow rate, cfm

Afloor = floor area, ft2

Nbr = number of bedrooms

For this test home, the continuous ventilation rate would be 66 cfm (3,570 ft2 of conditioned 

floor area and three bedrooms). The system commissioning tested the ventilation flow rate as 

133 cfm with the air handler operating in fan only mode. ASHRAE Standard 62.2 allows an 

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0

20

40

60

80

100

120

140

9/14/12 9/15/12 9/16/12

Demand, W

Temperature, F

DSH Loop Influence on DHW Tank Tempearture

DSH Loop Temp In DSH Loop Temp Out

DHW Tank Temp DHW Power Draw
21

exception for the effective ventilation rate of an intermittently operating system based on the fan 

flow rate during the on cycle, the base ventilation rate requirement, ventilation effectiveness, and 

system fractional on time.

Qf = Qr⁄(εf) (5)

where

Qf = fan flow rate during the on-cycle

Qr = ventilation air requirement

ε = ventilation effectiveness

f = fractional on time, defined as the on-time for one cycle divided by the 

cycle time

Given the tested ventilation flow rate for this home, the ventilation system could operate with a 

fractional on-time of 50% and deliver an effective ventilation rate that meets the ventilation 

standard. The ventilation controller used on this project, the Honeywell Y8150, includes 

simplified inputs for conditioned floor area, number of bedrooms, and ventilation airflow that 

were set for the test home and measured flow rate, Figure 17. This control also features a 

microcontroller, which optimizes ventilation air delivery based on normal HVAC run times 

(Honeywell International Inc., 2011). 

Figure 17. Ventilation control settings.

The energy impact of the system includes the added fan run time necessary to deliver ventilation 

air, above that of the system run time to meet space conditioning loads. To facilitate this 

analysis, measurements of air handler fan power draw and ventilation air dry-bulb temperature 

and relative humidity were collected. 

Following system commissioning and the installation of monitoring equipment, the homeowner 

contacted Southface complaining that the air handler fan ran continuously regardless of system 

calls for heating or cooling. Consultation with the system installer did not lead to a satisfactory 

solution, and the homeowner disconnected the controller in March 2012. The fan power draw 

data, shown in Figure 18, demonstrates the problem with the system. 
22

Figure 18. HVAC system operation, March 2012.

Until March 16, when the homeowner turned off the ventilation controller, the air handler fan ran 

continuously regardless of normal system operation, drawing a constant 290 W. Consultation 

with Honeywell revealed that improper wiring to the home’s zoned thermostats may have caused 

the problem, but the homeowner was not willing to revisit the ventilation operation and has since 

left the ventilation controller in the “off” position, relying on windows, natural air exchange, and 

point source exhaust to provide ventilation to the home. Since this change, the homeowner has 

not complained of any adverse health or comfort effects. 

Despite the installation issues with the ventilation controller, the measured data can still be used 

to determine the fan energy impact of this ventilation approach if the system had been operating 

correctly. Reviewing the measured data on a daily basis over the six-month period from January 

15 to July 15, 2012, revealed that, except for peak heating and cooling periods, the system 

fractional run time was below the 50% fractional run time needed to deliver an effective 

ventilation rate that meets ASHRAE 62.2; see Figure 19.

0

500

1000

1500

2000

2500

3000

3/1/12 3/6/12 3/11/12 3/16/12 3/21/12 3/26/12 3/31/12

Demand (kW)

HVAC System Operation

compressor_demand fan_demand
23

Figure 19. System fractional on time.

In order to deliver the 50% fractional run time needed to meet ASHRAE 62.2, the system would 

be required to run an additional 1,363 hours. Given the measured fan power draw for the system 

in fan-only mode, 290 W, this would result in 395 kWh of additional consumption, or roughly 

2% of the total house consumption, for this six-month period. Given that this house has high 

electric usage because it functions as a home office and has high exterior power loads, this 

percentage would be significantly higher in a typical home. 

4 Discussion

Reviewing whole house energy consumption for this home showed the significant additional 

energy consumption associated with non-typical end use loads including a home office, pool, 

landscape water feature, and other luxury features not accounted for in Building America 

modeling tools. While these end uses do not find their way into the typical home, these features 

are expected for the clientele of the owner architect. Over the six-month monitoring period, these 

non-typical loads made up 48% of the whole house energy consumption, as shown in Figure 5.

Removing these non-typical loads from the monitored whole house energy consumption, the 

measured results showed 21% greater energy use than modeled projections.

The results of energy modeling analysis and the monitored data gathered from this home reveal 

some limitations with using current Building America energy modeling tools to project whole 

house energy consumption. Most residential energy modeling tools, including BEopt, do not 

allow for the addition of non-typical end uses, so providing a realistic picture of anticipated 

whole house energy use will be difficult in similar cases where non-typical loads will be present.

Southface also found a large shift in the projected savings delivered by different BEopt software 

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Fractional on Time (%)

System Fractional on Time

System fractional on time 50% fractional on time
24

versions, BEoptE+ v1.1 and v1.3. These discrepancies were explained by updates to the 

software’s natural ventilation rates, HVAC sizing procedure, and dehumidification loads, but the 

large reduction in predicted savings reduces confidence in using the software as a tool to help 

future projects meet Building America savings goals. 

Similar to past Building America research on GSHPs, Southface found the in-field cooling 

efficiency for the home’s GSHP to be lower than the AHRI rated performance and 

manufacturer’s published product data, averaging 14.3 EER over the monitoring period 

compared to a rated efficiency of 18 EER. Adding the ground loop and DSH pump energy into 

the efficiency calculations accounts for some of this degraded performance, as does the added 

static pressure from the home’s duct system, but other installation issues likely caused additional 

loss of efficiency. Increased loop temperatures following system run times indicate that the 

ground loop for the system is likely undersized and that rule of thumb loop sizing did not provide 

adequate heat exchange for this home. The system zoning also likely contributed to reduced 

efficiency, as the system often short cycled, running in the high stage to meet the load of a single 

zone. Additional issues with the installation of the home’s ventilation control show that HVAC 

system design and installation best practices should remain focus areas for Building America.

In answering the question of real versus perceived value for GSHP systems, the research findings 

do not show an increase in efficiency far above that of traditional air-source systems. Data rated 

from AHRI for high efficiency ASHPs gives cooling efficiency values ranging from 

approximately 11 to 14 EER (AHRI, 2013). While the in-field performance for these systems 

would suffer the same reduction associated with the home’s duct system and other factors that

are not included in rated conditions, there is no added energy consumption associated with 

ground loop or DSH pumps. The in-field efficiency measurements from this research do not 

show a cost-effective argument for the inclusion of GSHPs in the pursuit of increased energy 

savings; however, these systems do provide additional aesthetic and comfort factors that may be 

of value to homeowners. If properly sized and controlled, a GSHP may also provide better part 

load performance and avoid the use of electric supplemental heat in extreme heating conditions 

associated with traditional ASHP systems.

The monitoring effort for this home will continue through early 2013. Southface plans to collect 

information on GSHP heating efficiency and assist the homeowners with recommendations to 

reduce whole house energy consumption, particularly from the large loads associated with the

home’s pool and landscape water feature. 

5 Conclusion

This new construction test home provided valuable information on current construction best 

practices for homes in the mixed humid climate. The information can be used to provide 

guidance to future Building America industry partners on the path towards achieving 50% whole 

house energy savings. Following are research questions and answers regarding this home:

• Is the measured energy use for heating and cooling consistent with modeled estimates, given 

similar ambient weather conditions?
25

Removing non-typical loads from the monitored whole house energy consumption, measured 

data showed 21% greater energy use than weather normalized modeled projections with a 

majority of this increase traced to HVAC consumption.

• How does the efficiency of the GSHP compare to AHRI ratings and manufacturer’s 

published data?

The measured in-field cooling efficiency for the home’s GSHP was 14.3 EER, a 20% 

reduction from the rated efficiency. The reduced efficiency can be traced to the addition of 

ground loop and DSH pump energy to the efficiency calculation and other differences from 

rated conditions, including a full duct system with higher static pressure. Southface believes 

inadequate loop sizing and improper controls settings, which caused the unit to short cycle in 

the high stage, also had an impact on lowering the measured efficiency.

• Is “rule of thumb” loop sizing adequate for this application? 

Given the large rise in incoming ground loop temperatures observed during periods of 

extended run time, Southface does not believe that the home’s ground loop, including five 

250-ft vertical wells, provides adequate heat exchange. The vertical bores for this project 

were based on basic rule of thumb assumptions and the rate at which the loop temp increases 

suggests that the design may have benefitted from more detailed analysis including soil 

conductivity testing. While the cost of this is greater, the fact that the loop is essentially a 

permanent component of the system may make this cost worthwhile.

• What is the additional fan energy associated with the CFIS ventilation system?

While the ventilation system controls did not function as intended, the monitored data for system 

run time provided enough information to determine the added fan power associated with this 

ventilation strategy had the system been controlled properly. In order to deliver the 50% 

fractional run time needed to meet ASHRAE 62.2, the system would be required to run an 

additional 1,363 hours. Given the measured fan power draw for the system in fan-only mode, 

290 W, this would result in 395 kWh of additional consumption for the six-month monitoring 

period.
26

References

AHRI. (2013.). Directory of Certified Product Performance. Air-conditioning, Heating, and 

Refrigeration Institute. Retrieved September 26, 2012, from 

http://www.ahridirectory.org/ahridirectory/pages/hp/defaultSearch.aspx

Honeywell International Inc. (2011). Y8150 Fresh Air Ventilation System, W8150 Fresh Air 

Ventilation Control Product Data. Golden Valley, MN. Accessed at: 

http://www.forwardthinking.honeywell.com/related_links/ventilation/y8150/install/68_0282.pdf.

NREL. (2012). Building America Critical Path Innovations Leading to 50% Savings (Internalonly report). Golden, CO: National Renewable Energy Laboratory on behalf of U.S. Department 

of Energy.

Puttagunta, S., Aldrich, R., Owens, D., and Mantha, P. (2010). Residential Ground-Source Heat 

Pumps: In-Field System Performance and Energy Modeling. GRC Transactions, vol. 34, 941-8. 

Accessed at: 

http://www.builditsolar.com/Projects/SpaceHeating/InField%20PerformanceTestingofGSHP_up

dated%2011_11_2010.pdf.

Puttagunta, S. and Shapiro, C. (2012). An In-Depth Look at Ground Source Heat Pumps and 

Other Electric Loads in Two GreenMax Homes. Norwalk, CT: Consortium for Advanced 

Residential Buildings on behalf of the U.S. Department of Energy Building America program. 

Accessed at: 

http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/ground_sourcehp_gre

enmax.pdf.

Wilcox, S. and Marion, W. (2008). Users Manual for TMY3 Data Sets (Revised). Golden, CO: 

National Renewable Energy Laboratory. Accessed at: 

http://www.nrel.gov/docs/fy08osti/43156.pdf
27

6 Appendices

Appendix A: Monitoring Diagrams

Figure 20. Monitoring diagram.
28

Table 5. List of Monitoring Equipment.

Measurement Equipment

Electric energy Trendpoint Enersure Power Meter 

Duct air temperature, humidity Vaisala HMD40Y

Ground/DSH loop flow Seametrics SPX-100/SPX-050

Pulse Counter Obvius Modhopper 9120-3SN

Ground/DSH loop temperature Omega TC-J-NPT-U-72

Water heater tank temperature Omega M12JSS-1/4-U-12-B

Thermocouple Data Acquisition Adam 4118 Thermocouple Input 

Module

Wireless Sensor Receiver Obvius Modhopper 9120-3SN

Temperature, Humidity Point Six Wireless 

Temperature/Humidity Sensor

Sensor Signal Conversion/Data 

Recording 

Obvius Acquisuite A8812-1
29

Appendix B: Project Map and Location

Figure 21. TaC Studios residence location. Credit: Map Data © 2012 Google, Sanborn
buildingamerica.gov

DOE/GO-102013-3889 ▪ December 2013

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