Performance of a Hot-Dry 

Climate Whole-House 

Retrofit 

E. Weitzel, A. German, and E. Porse

Alliance for Residential Building Innovation

June 2014
NOTICE

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iii

Performance of a Hot-Dry Climate Whole-House Retrofit

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: 

Elizabeth Weitzel

Alliance for Residential Building Innovation (ARBI)

Davis Energy Group, Team Lead 

123 C Street 

Davis, California 95616 

NREL Technical Monitor: Michael Gestwick

Prepared under Subcontract No. KNDJ-0-40340-03 

June 2014 
iv

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v 

Contents

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

List of Tables .............................................................................................................................................. vi

Definitions.................................................................................................................................................. vii

Acknowledgments ..................................................................................................................................... ix

Executive Summary.................................................................................................................................... x

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

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

1.2 Research Questions ..............................................................................................................2

2 Characterization of Site and Retrofit Measures ................................................................................ 3

2.1 Residence Description .........................................................................................................3

2.2 Retrofit Measure Options and Details..................................................................................4

2.3 Preliminary Savings Estimations .........................................................................................8

3 Evaluation Methodology .................................................................................................................... 10

3.1 General Technical Approach .............................................................................................10

3.2 Measurements ....................................................................................................................10

3.2.1 Short-Term Tests ...................................................................................................10

3.2.2 Monitoring Points ..................................................................................................10

3.3 Utility Bill Disaggregation and Model Calibration ...........................................................11

4 Results and Discussion..................................................................................................................... 13

4.1 Short-Term Test Results ....................................................................................................13

4.2 System Commissioning .....................................................................................................13

4.3 Annual Energy Use ............................................................................................................14

4.4 Project Economics .............................................................................................................18

4.5 Homeowner Feedback .......................................................................................................19

5 Conclusions and Recommendations ............................................................................................... 22

References................................................................................................................................................. 24

Appendix: Homeowner Survey................................................................................................................ 25
vi 

List of Figures

Figure 1. Front view of Stockton house.................................................................................................... 3

Figure 2. BEopt optimization curve........................................................................................................... 6

Figure 3. Assumed seasonal effect on water heating loads................................................................. 12

Figure 4. Natural gas usage (pre- and post-retrofit).............................................................................. 14

Figure 5. Electrical energy usage (pre- and post-retrofit)..................................................................... 15

Figure 6. Monthly calculated source energy savings from utility bill ................................................. 17

Figure 7. Normalized source energy savings (TMY3) ........................................................................... 17

Figure 8. Winter comfort levels ............................................................................................................... 20

Figure 9. Summer comfort levels ............................................................................................................ 20

Unless otherwise noted, all figures were created by the ARBI team.

List of Tables

Table 1. Building Energy Efficiency Improvements ................................................................................ 4

Table 2. Measure Incremental Costs......................................................................................................... 5

Table 3. BEopt Projected Annual Site Energy Use of the Pre-Retrofit and Post-Retrofit Building .... 8

Table 4. BEopt Projected Annual Source Energy for the Pre-Retrofit and Post-Retrofit Building..... 9

Table 5. Measurement Point List............................................................................................................. 11

Table 6. Sensor Specifications ................................................................................................................ 11

Table 7. Short-Term Diagnostic Test Results ........................................................................................ 13

Table 8. Characterization of Pre- and Post-Retrofit Weather, Projected Energy Use, and Costs .... 16

Table 9. Projected Savings and Cost Effectiveness.............................................................................. 18

Table 10. Comparison of Standard and Whole-House Retrofit Package Savings and Economics.. 19

Unless otherwise noted, all tables were created by the ARBI team.
vii 

Definitions

ACCA Air Conditioning Contractors of America

ACH50 Air changes per hour at a pressure difference of 50 Pascal

AFUE Annual Fuel Utilization Efficiency

ARBI Alliance for Residential Building Innovation

ASHRAE American Society for Heating, Refrigerating and Air 

Conditioning Engineers 

BEoptTM Building Energy Optimization simulation

Btu British Thermal Units

CDD Cooling Degree Day

CFL Compact Fluorescent Lamp

CFM Cubic feet per minute

CFM50 Cubic feet per minute at a pressure differential of 50 Pascal

DEG Davis Energy Group, Inc.

EER Energy Efficiency Ratio

EF Energy Factor

GHS Green Home Solutions by Grupe

HDD Heating Degree Day

HEU Home Energy Upgrade

HVAC Heating, Ventilation, and Air Conditioning

kWh Kilowatt-hour

MEL Miscellaneous Electric Load

RH Relative Humidity (%)

RTD Resistive temperature device

SCFM Standard cubic feet per minute
viii

SEER Seasonal Energy Efficiency Ratio

SHGC Solar Heat Gain Coefficient

TMY3 Typical Meteorological Year 3

UV Ultraviolet
ix

Acknowledgments

Davis Energy Group would like to acknowledge the U.S. Department of Energy Building 

America Program for its funding and support of this research effort. In addition, we would like to 

thank Green Home Solutions, for its cooperation and coordination throughout all stages of this 

project.
x 

Executive Summary

The Stockton house retrofit is a two-story Tudor style single-family home located in Stockton, 

California. Although classified as a hot-dry climate region, Stockton generally has relatively 

mild summers due to its proximity to the San Joaquin Delta that brings in cool night-time breezes 

from the San Francisco Bay Area. The homeowners completed a whole-house energy retrofit

under a Stockton area Large-Scale Retrofit Program administered by the Alliance for Residential 

Building Innovation (ARBI). The implemented retrofit package included: 

• Heating, ventilation, and air conditioning, water heater, and window replacements 

• Duct sealing

• Adding attic and floor insulation

• Envelope sealing

• Domestic hot water pipe insulation

• Compact fluorescent lamp replacements 

• Mechanical ventilation upgrades. 

The objective of this work is to expand the level of understanding of whole-house retrofit 

impacts in climates where lighting and miscellaneous electric loads represent a large fraction of 

annual energy consumption. In many climates with high space conditioning loads, whole-house 

retrofits can demonstrate significant operating cost savings and favorable economics through the 

reduction of space conditioning energy consumption. In milder climates, similar to that of 

Stockton, whole-house retrofits represent an opportunity to evaluate overall performance and 

cost-effectiveness, and to develop findings that will assist future efforts. This information is 

important for the home energy retrofit industry as it gains a better understanding of cost and 

performance tradeoffs in a range of applications and climates.

Source energy savings (normalized to a Typical Meteorological Year’s weather data, TMY3) 

with the whole-house retrofit were estimated at 23% compared to the pre-retrofit case, or 15 

percentage points higher than the projected 8% savings identified for the basic package of 

measures typically implemented in the Large-Scale Retrofit Program project1

. Projected (TMY3) 

annual energy savings totaling 1,377 kWh and 295 therms/year were largely a result of the water 

heater upgrade and reduced furnace heating consumption (improved furnace efficiency and load 

reduction benefits due to envelope sealing, added insulation, and duct sealing). Savings were 

considerably lower than the 47% savings identified with BEopt modeling, primarily due to very 

low cooling energy usage and much higher than typical miscellaneous electric loads 

(representing 40% of annual source energy in the Stockton house). The economics could not 

generate a favorable cash flow for the standard package of measures due to high financed costs 

and lower than typical heating, ventilation, and air conditioning system operation. This whole-

 

1 Standard package includes R-49 attic insulation, duct replacement, envelope sealing, hot-water pipe insulation,

water heater blanket, lighting upgrade to high efficacy lamps, low-flush toilet upgrade, and mechanical ventilation 

upgrade. 
xi 

house retrofit package promised additional utility savings, but could not bridge the gap of cost 

effectiveness. 

Despite the lower than expected savings, the homeowner expressed a high degree of satisfaction 

with the retrofit and the improved comfort. The project highlighted the complexities that occur in 

implementing projects that go beyond the simple envelope/duct sealing and attic insulation steps.

The more complicated whole-house retrofits must integrate homeowner priorities, as well as deal 

with more costly implementation issues. In this specific case, a window retrofit was a high 

priority for the homeowner, despite the $11,000 cost and poor economics. Mild climate wholehouse retrofits are challenged by reduced paybacks for many measures. Learning how to 

maximize the cost effectiveness of whole-house energy retrofits and developing a viable 

approach to addressing miscellaneous energy use are key needs for developing effective retrofit 

strategies.
1 

1 Introduction

1.1 Background

The Stockton (California) House retrofit is part of The Energy Challenge in Stockton project.

This pilot project is administered by Davis Energy Group (DEG) and funded by the California 

Energy Commission and the Alliance for Residential Building Innovation (ARBI) team for 

Building America. The Large-Scale Retrofit Program pilot project primary objective is to 

increase energy efficiency in the residential sector through improved uptake of whole-house 

Home Energy Upgrades (HEUs). The Energy Challenge aims to develop a market for energy 

efficiency retrofits through consumer outreach and education, identification of market 

efficiencies, and promotion of HEUs in the marketplace. The pilot uses a deemed cost-effective 

Standard Package of energy efficiency measures consisting of the following: 

• R-49 attic insulation

• Duct replacement

• Envelope sealing 

• Hot-water pipe insulation

• Water heater blanket

• Lighting upgrade to high efficacy lamps 

• Low-flush toilet upgrade 

• Mechanical ventilation upgrade. 

The Standard Package is designed to meet annual site energy savings of 25% and cost 

participants $9,456 ($6,706 after rebates and incentives). A comprehensive “whole-house” 

retrofit would include additional measures (e.g., heating, ventilation, and air conditioning 

[HVAC] equipment replacement and/or window replacement), generating additional energy 

savings and thermal comfort, but at a higher cost and tailored to the individual home. Although 

the Energy Challenge in Stockton has successfully marketed Standard Package HEUs with more 

than 165 retrofits completed to date, the Stockton House whole-house retrofit project is one of 

the few HEUs implemented that includes additional energy efficiency measures. Thus, the 

Stockton House offers a unique opportunity to study and document the energy performance and 

cost effectiveness of the more complicated retrofit savings, as well as gauge occupant 

satisfaction. Results can inform program design and marketing activities, including efforts to 

develop more effective incentives to homeowners participating in the HEU process. Previous 

research has identified early adopters as an important tool in encouraging broader 

implementation of retrofit programs within a neighborhood (Berman et al. 2012). 

For the Stockton House whole-house retrofit project, homeowner dissatisfaction with existing 

energy bills and overall comfort were key motivators for pursuing the whole-house retrofit. The 

link between energy efficiency, increased occupant satisfaction, and enhanced home resale price 

is a potentially powerful marketing tool that is just beginning to gain recognition (Kok and Kahn 

2012). Identifying cost-optimized climate appropriate packages through detailed modeling 

(Fairey and Parker 2012) is a valuable step in the evolution of the HEU industry, but the 
2 

implementation and documentation of projects such as this are also needed to develop case 

studies that inform stakeholders and the broader public on how implementation may be impacted 

by site constraints, homeowner input, and available financial resources. 

1.2 Research Questions

The following research questions were explored in this study: 

1. Are there measured savings and homeowner comfort benefits resulting from whole-house 

retrofits that may motivate homeowners to invest more in whole-house retrofits as 

opposed to more standard upgrades? 

2. What energy upgrade strategies are most effective (in terms of cost and energy savings) 

in whole-house retrofit projects? 

The study used a combination of pre- and post-retrofit energy simulations to predict energy 

savings, monitoring of site energy use to document end use performance, and an assessment of 

homeowner feedback to determine qualitative response to the retrofit activities. 
3 

2 Characterization of Site and Retrofit Measures 

2.1 Residence Description

The Stockton House is a two-story, Tudor-style single-family home located in Stockton, 

California (Figure 1), approximately 90 miles east of San Francisco. Although the climate is 

defined as Hot-Dry by Building America conventions,2 the summer climate is considerably more 

moderate than much of California’s central valley, due to the proximity to the San Francisco Bay 

Area. Based on Typical Meteorological Year (TMY3)3 data, Stockton experiences an average of

2,494 heating degree days (HDDs) and 1,295 cooling degree days (CDDs), on a 65°F base. 

Figure 1. Front view of Stockton house 

The 2,152-ft2 home was originally built in 1939 and is currently occupied by an adult couple. 

The house has a combined raised floor and partial basement foundation. Table 1 summarizes the 

pre-retrofit conditions and the energy efficiency improvements implemented as part of the 

whole-house retrofit. 

 

2 and climate zone 3B by the International Energy Conservation Code. 3 Statistics for USA_CA_Stockton.Metro.AP.724920_TMY3

http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=4_north_and_central_america_w

mo_region_4/country=1_usa/cname=USA#CA
4 

Table 1. Building Energy Efficiency Improvements

Measure Pre-Retrofit Post-Retrofit

Basic Building Characteristics

Building Type/Stories Single-family, 2-story, 

partial basement

Single-family, 2 story, 

partial basement

Conditioned Floor Area 2,152 2,152

Number of Bedrooms 3 3

Envelope

Attic Vented, R-11 Vented, R-49

Roof

Wall Insulation

Tile

None

Tile

None

Raised Floor Insulation None R-19

Framing Standard 2 × 4, 16 in. o.c. Standard 2 × 4, 16 in. o.c.

Glazing Properties

Window Type Metal single pane Vinyl dual pane

U-Value/SHGCa 1.28/0.80 0.30/0.30

HVAC Equipment

Heating System Type and 

Rated Efficiency

Natural gas (64% AFUEb)

Single speed, 105 kBtu/h

Natural gas (95% AFUE) 

Two speed, 64–92 kBtu/h

Cooling System Type and 

Rated Efficiency 8 SEERc

/7.7 EERd 16 SEER/12 EER

Ventilation

Ducting

Kitchen and one bath fan 

R-2.1 

Kitchen and two bath fans

Crawlspace and attic R-8, 

Interstitial space R-2.1 

Water Heating Equipment

Water Heater Type and 

Efficiency Natural gas storage 0.62 EFe Condensing tanklessNatural gas 0.96 EF

Tank Capacity/Gallons 40,000 Btu/h 50 gal 15,000 - 150,000 Btu/h

Appliances and Lighting

Appliances ENERGY STAR clothes 

washer, dryer

ENERGY STAR clothes 

washer, dryer

Dryer Fuel Electric Electric

Oven/Range Fuel Natural gas Natural gas

Lighting 100% CFLf 100% CFL a Solar heat gain coefficient

b Annual fuel utilization efficiency

c Seasonal energy efficiency ratio

d Energy efficiency ratio

e Energy factor

f Compact fluorescent lamp

2.2 Retrofit Measure Options and Details

The Stockton House retrofit opportunity was identified and executed by Building America 

Partner Green Home Solutions by Grupe (GHS). Construction work was completed early fall 

2011. Cost data provided by GHS indicated total upgrade costs of $38,000. Table 2 summarizes

the installed retrofit measures and their associated costs. The incremental cost for the new 
5 

HVAC system reflects the cost difference between a federal minimum efficiency unit and the 

selected high efficiency unit since the equipment had reached the end of its useful life. 

Table 2. Measure Incremental Costs

Measure Original Building Retrofit Measure Installed 

Costs

Incremental 

EEM Costs

Thermal Envelope

Attic

Raised Floor 

Insulation Glazing

Vented, R-11

None 

Metal/single pane 

U = 1.28; 

SHGC = 0.80

Vented, R-49

R-19 

Vinyl/dual pane 

U = 0.30; 

SHGC = 0.30

$3,464 

$1,882 

$10,897 

$3,464 

$1,882 

$10,897 

Asbestos Removal Ducting Removed $2,014 -

Infiltration 5,850 CFM50 2,500 CFM50 $1,754 $1,754

HVAC System

Heating

Air Conditioning

Ultraviolet (UV) 

Lamp

(45 years old)

Natural gas 

furnace 

64% AFUE

8 SEER/7.7 EER 

4.0 ton 

None

Natural gas two 

speed furnace

95% AFUE

16 SEER/12 EER

4.0 ton 

Installed

$7,892 

$300 

$1,164 (versus 

minimum 

efficiency system 

replacement cost)

– 

Ducting Insulation

Duct Leakage

Crawlspace R-2.1

Attic R-2.1 

36% CFM25

Crawlspace R-8

Attic R-8 

12% CFM25

$4,238 $4,238 

Fresh air 

Ventilation Existing bath fan Additional bath fan $852 – 

Water Heating 13 year old gas

storage (0.62 EF)

Condensing

Tankless (0.96 EF) $4,357 $4,357 

Lighting 100% CFL 100% CFL $350 –

Total

Available Incentives

Net Cost

$38,000

($4,000) 

$34,000

$27,756

$23,756

During the initial consultation and planning stages, an energy simulation model was completed 

using BEopt v1.1 (later updated to BEopt v1.2) to analyze the potential measures. The 

homeowner provided a maximum budget for the retrofit. The owner also requested that no 

modifications be made to the existing lath-and-plaster walls or the exterior stucco finish, which 

ruled out the additional wall insulation that would have made a deeper impact on savings. The 

existing HVAC system needed routine replacement and the identified replacement for the project 

was a two-speed 95% AFUE furnace and a 16 SEER/12 EER air conditioning unit, exceeding the 

code-compliant system nominal performance of 80% AFUE and 13 SEER. 

Figure 2 shows the least cost curve generated through the BEopt optimization process based on 

the costs presented in Table 2. The post-retrofit efficiency package is reflected by the red mark

on the chart and it can be seen that this package is above the least cost curve. Note that around 

50% savings, the slope of the curve steepens substantially indicating that further efficiency

improvements will only be achieved at a high cost. A point along the least cost curve which 
6 

achieves similar savings as the proposed package (47%) differs from the proposed package in the 

following areas: 

• R-13 wall insulation

• No additional attic insulation

• No window upgrade 

• No duct upgrade. 

The contractor’s costs for attic and floor insulation and duct sealing/insulating were substantially 

higher than what has been observed from other contractors in California. Case studies have 

demonstrated that these measures, particularly ductwork and attic insulation, are accepted as 

cost-effective components of retrofits in hot-dry climates (PNNL 2009a, 2009b; DOE 2010a, 

2010b). Window upgrades in single-family homes are rarely deemed cost effective from a purely 

energy savings perspective, especially in milder climates. However, there are other motivations 

for replacing windows, primarily from an occupant comfort perspective. As noted above, adding 

wall insulation was not an option in this project. 

Figure 2. BEopt optimization curve 

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

$4,000

$4,500

0 10 20 30 40 50 60

Annualized Energy Related Costs ($/yr)

Avg. Source Energy Savings (%/yr)

Least Cost Curve & 

Optimization Curve
7 

Using the BEopt model, the final set of recommended measures was optimized given the project

constraints. The following lists detailed information for many of the selected retrofit measures 

and discusses their tradeoffs as appropriate. 

• Raised floor insulation: The raised floor was insulated with R-19 fiberglass batt 

insulation using wire hangers installed at 18-in. intervals. Care was taken to prevent 

restriction of the crawlspace vents to maintain proper crawlspace airflow and avoid 

potential crawlspace moisture problems. A vapor barrier was not installed on the existing 

dirt floor due to the dry climate and low soil moisture content. 

• Windows: The existing windows were single-pane metal windows with an assumed Uvalue of 1.28 and an SHGC of 0.80. Based on homeowner feedback, the windows 

provided unacceptable performance and were therefore a high priority retrofit 

opportunity. The proposed windows have a U-value of 0.30 and an SHGC of 0.30, and 

are anticipated to contribute to the improved occupant comfort through reduced radiant 

heat transfer, noise reduction, and reduced drafts from both induced sources and direct air 

leakage. Window replacement also reduces the detrimental effects from condensation 

common with single pane, aluminum frame windows. In addition to the energy and 

comfort benefits associated with window replacement, there are also home and resale 

value benefits for the homeowner.

• Envelope sealing: During a blower door test, air leakage in the existing building was 

estimated to be above average at 21.2 ACH50.4

 DEG completed an inspection while the 

blower door was active and traced a large amount of envelope leakage to the basement 

door seals, upstairs storage space access doors to knee walls, openings to the crawlspace 

under the kitchen sink, and gaps at the stairs directly over the unconditioned basement. 

The measured post-retrofit air leakage at test out was 8.2 ACH50.

• HVAC: Although the existing HVAC system was 45 years old, it was well maintained 

and found to be in reasonably good condition. Based on equipment age, however, 

replacement was recommended. The upgraded system is a high efficiency (95% AFUE) 

two-stage furnace, coupled with a 16 SEER/12 EER condensing unit. GHS completed 

heating and cooling equipment sizing using Recurve software,

5

 which utilizes a sizing 

methodology equivalent to ACCA Manual J (ACCA 2006). Ducts are located in the 

crawlspace, in interstitial wall spaces between the first and second floors, and in the attic. 

Ducts in the crawlspace and attic spaces were upgraded with R-8 flex duct and 

inaccessible ducts located in interstitial spaces were not altered. 

• Water heating: The existing water heater is located in the partial basement and was 

installed in 1998. The upgraded water heating system is a high efficiency (96 EF) 

condensing tankless model that was installed on the exterior of the house. A demand 

recirculation pump with push button control was installed due to the long pipe run (and 

hot water wait times) to the first floor bathroom with the existing distribution system. The 

 

4 The blower door test was not able to reach 50 Pascal during test-in and the ACH50 was approximated using the 

following equation: ACH50 = ACHP*(50/P)^0.65, where P is the maximum pressure that was achieved. 5 http://apps1.eere.energy.gov/buildings/tools_directory/software.cfm/ID=593/pagename=alpha_list_sub 
8 

first floor bathroom was added after the house was built and modifying the existing hot 

water distribution system was deemed to be too expensive. 

• Lighting: While the house already had been upgraded to 100% CFL screw-in lights over 

time, the contractor still recommended to change out all bulbs, as is included in its

standard retrofit package.

2.3 Preliminary Savings Estimations

Energy simulations were performed using BEopt v1.2 to estimate energy savings of the house 

using the Building America House Simulation Protocols for existing buildings. The pre-retrofit 

energy use was estimated using existing building conditions and post-retrofit energy use was 

estimated by applying proposed energy efficiency measures to the existing building. The 

thermostat schedules were adjusted in BEopt to match actual set points employed by the owner. 

Additionally, annual miscellaneous electric load (MEL) usage was adjusted such that total noncooling/heating electricity use (lighting + appliances + MEL + exhaust fans) reflected actual 

annual consumption from monitoring data. Standard BEopt assumptions resulted in much higher 

MEL use than observed. Table 3 presents annual BEopt projected gas and electricity

consumption by end use and Table 4 presents site and source energy savings. 

Table 3. BEopt Projected Annual Site Energy Use of the Pre-Retrofit and Post-Retrofit Building

End Use Pre-Retrofit Post-Retrofit

kWh therm kWh therm

Space Heating 595 861 182 340

Space Cooling 4,517 – 1,448 –

DHW - 151 - 99

Lighting 1,130 – 1,130 –

Appliances and MELs 2,881 29 2,884 29

Fresh Air Ventilation 16 – 22 –

Total Usage 9,139 1,041 5,666 468
9 

Table 4. BEopt Projected Annual Source Energy for the Pre-Retrofit and Post-Retrofit Building 

End Use

Estimated Annual Source 

Energy6 Source Energy Savings 

PreRetrofit 

(MBtu)

PostRetrofit 

(MBtu)

% of End 

Use Versus

Pre-Retrofit

% of Total 

Versus

Pre-Retrofit

Space Heating 101 39 61% 28%

Space Cooling 52 17 68% 16%

DHW 17 11 35% 3%

Lighting 13 13 0% 0%

Appliances and MELs 36 36 0% 0%

Fresh Air Ventilation 0.2 0.3 –39%7 0%

Total Usage 219 116 47% 47%

 

6 Source ratios of 3.365 source Btu/kWh is used for grid electricity and 1.092 source Btu/Btu for natural gas.

7 The negative savings are due to the addition of a second bath fan. 
10 

3 Evaluation Methodology

3.1 General Technical Approach

Short-term tests, long-term monitoring, and modeling were all used to identify the attributes of 

performance, cost, and comfort related to the retrofit measures. A final homeowner assessment 

was performed to determine perceived comfort and value of the retrofit. Monitoring data for a 

full year were compiled for whole-house electric and HVAC and water heating equipment gas 

and electrical end use, along with indoor and outdoor temperature and relative humidity (RH). 

Data were compared to utility bill data to disaggregate uses and savings. 

Monitoring data were carefully reviewed and analyzed in an effort to respond to research 

questions and to identify sources of energy savings (e.g., reduced heating and cooling load, 

improved equipment efficiency). At the conclusion of the monitoring period, the homeowners 

were surveyed to qualitatively evaluate their satisfaction and perception of comfort in the postretrofit home. An economic analysis was completed to determine the cost effectiveness and 

viability of incremental costs for whole-house retrofit measures. Post-retrofit energy

consumption was compared relative to the pre-retrofit energy consumption using Building 

America House Simulation Protocol schedules.

The specific technical approach for evaluating the energy use of the post-retrofit house was to 

measure furnace and air conditioner energy use, total house energy use, and domestic hot water 

energy use. Indoor temperature and RH were recorded on the first and second floors, while 

outdoor temperature and RH were recorded on the north side of the house. 

3.2 Measurements

The site was equipped with a DataTaker data logger, sensors, and modem to continuously 

collect, store, and transfer data via telephone lines. Sensors were scanned every 15 seconds, with 

data summed or averaged, as appropriate, and stored in the data logger memory every 15 

minutes. Data were downloaded every 24 hours, and range checks were automatically performed 

to identify problems with monitoring sensors or the systems being monitored. The monitoring 

period lasted from mid-September 2011 to mid-September 2012. 

3.2.1 Short-Term Tests

Short-term tests were conducted before and after the retrofit to verify air tightness of the building 

envelope and the duct system. Blower door tests measured envelope leakage and a duct 

pressurization test measured duct leakage.

3.2.2 Monitoring Points

Table 5 lists all the measurement points that were monitored on a continuous basis. Total house 

electricity measured did not include the spa and workshop, which are included in the utility bills 

but are extraneous to the house performance. 

Standard specifications for the sensor types used are listed in Table 6. Sensor selection was based 

on functionality, accuracy, cost, reliability, and durability. Specific model numbers are listed as 

examples; similar models by other manufacturers may be used. Signal ranges for temperature 

sensors correspond approximately to listed spans. 
11 

Table 5. Measurement Point List 

Point 

No. Abbrev. Description Location Sensor Type

Sensor 

Manufacturer 

Model

1 TAO Temperature, air, 

outdoors North side RTD*, 4-20mA

Gen Eastern 

MRHT3-2-1

2 RHO RH, outdoors

3 TAI1 Indoor temperature, 1st 

floor 1st floor RTD, 4-20mA

Gen EasternHumitrac

4 RHI1 Indoor air RH, 1st floor

5 TAI2 Indoor temperature, 2nd 

floor 2nd floor RTD, 4-20mA

Gen EasternHumitrac

6 RHI2 Indoor air RH, 2nd floor

7 GASFURN Furnace gas use

Basement 

near Furnace

Pulsing

gas meter IMAC AC-250 

8 GASWH Water heater gas use Outside at 

tankless Unit

Pulsing 

gas meter IMAC AC-250 

9 EFAN Energy, air handler Basement at 

furnace

Power 

Monitor

Wattnode/WNA1P-240-P

10 ECOND Energy, condensing unit House 

breaker panel

Power 

Monitor

Wattnode/WNA1P-240-P

11 EHOUSE Energy, whole-house

(w/out spa/workshop)

House 

breaker panel

Power 

Monitor

Wattnode/WNA1P-240-P

* Resistive temperature device

Table 6. Sensor Specifications

Type Application Manufacturer/

Model Signal Span Accuracy

RTD

Outdoor 

temperature and 

RH

GE MRHT3 4-20 mA 

32°–132°F ±1.5%

0%–100% +2% RH

RTD Indoor/duct 

temperature/RH GE Humitrac 4-20 mA 32°–122°F ±1.5%

0%–100% +2% RH

Small 

Power 

Monitor

Fan and condenser 

power 

WattNode

pulse CTA/40 ±0.5% WNA-1-P-240-P 

Diaphragm 

Gas Meter Tankless gas use IMAC/Rockwell Pulse 250 SCFM ±1 ft3

3.3 Utility Bill Disaggregation and Model Calibration 

The pre-retrofit energy use was evaluated using a combination of utility bills, weather-station 

data and an estimate of weather-normalized water heating loads.

8 At first, the base loads were 

isolated by the assumption that the gas usage during the summer would be accounted for by the 

 

8 A curve that estimates the change in water heating loads based on heating degree days, based on prior research 

monitoring data (Berman et al. 2012).
12 

water heater and range only, while the electricity usage during the winter would account for the 

MELs and fan usage only. Any additional gas and electricity use would be assumed space 

heating and cooling respectively.

To separate the water heating gas usage from the gas cooking loads, the minimum gas use was 

applied to a curve (Figure 3) relating the change in consumption as a function of HDDs based on 

a method developed from prior monitoring at three homes in the Stockton climate (Berman et al. 

2012). The local weather station (Stockton Metropolitan Airport) provided the source for 

historical data, including HDDs and CDDs. 

Figure 3. Assumed seasonal effect on water heating loads

The data from the pre-retrofit utility bills were further analyzed to determine the weathernormalized effect on the energy use. The gas usage (in therms/day) was charted against daily 

HDD, to characterize the variation of heating gas use on outdoor weather conditions. The curve 

fit provided a direct relationship to use with TMY3 data to determine weather-normalized gas 

usage. The gas usage was then charted against average outdoor temperatures to determine the 

balance point, or the temperature at which the homeowner is more inclined to call for space 

heating. A similar process was completed to determine the cooling balance point. The electricity 

usage was charted against average daily HDDs and CDDs, to determine the seasonal influence 

on electric loads. The curve fits acquired were then combined to develop a relationship of 

electricity usage based on HDDs and CDDs. The same method was applied to post-retrofit utility 

bills, to provide a direct comparison of the pre-and post-retrofit performance over TMY3. 

0.00

0.50

1.00

1.50

2.00

2.50

Water Heating Monthly Multiplier
13 

4 Results and Discussion

4.1 Short-Term Test Results

Diagnostic testing was conducted at the start of the retrofit by DEG and GHS to verify existing 

conditions. At the conclusion of the retrofit, GHS retested to document post-retrofit envelope and 

duct leakage levels. Table 7 summarizes the short term test findings. 

Table 7. Short-Term Diagnostic Test Results

Short Term Test Original Post-Retrofit

Blower Door Infiltration 21.2 ACH509 8.2 ACH50

Duct Blaster Test @ 25 Pascals 36% of supply CFM 12% of supply CFM

4.2 System Commissioning

The contractor began the retrofit on August 9 and concluded the work on September 14, 2011. 

DEG commissioned the monitoring system 2 days later, September 16 and monitored through 

September 2012. Utility bill and modeling data were used to analyze pre-retrofit energy usage, as 

DEG was unable to gain access to install monitoring equipment before the construction was 

initiated. The electricity loads from the workshop and spa were extracted from the difference of 

post-retrofit monitoring and utility bill data and used in the base assumptions for the pre-retrofit 

period. The homeowner provided utility bills for the period of April 2009 through July 2011 

(pre-retrofit), and September 2011 through September 2012 (post-retrofit). 

Monitoring data were reviewed weekly to verify the integrity of the data stream, which proved 

valuable in aiding the commissioning process. Two weeks after commissioning of the HVAC 

system, the furnace shut off due to sensed exhaust flow restrictions, which required a technician 

visit. During the site visit, DEG noticed a continual 30-Watt draw from the air handler and 

determined the UV lamp was incorrectly configured and was operating continuously. The 

technician was able to reconfigure the UV lamp to operate only during fan operation. The UV 

lamp was an additional retrofit option requested by the homeowner and is not typical of most 

furnace installations.

By December, the homeowner noted that the furnace was running more frequently than he 

expected and was therefore concerned about higher gas bills. The thermostat has an adaptive 

recovery function that controls furnace operation so that full temperature setup is achieved by the 

time the thermostat schedule moves from “sleep” to “wake.” The adaptive control was activating 

earlier than expected and was subsequently disabled. With some continual concerns over system 

heating operation, a DEG technician visited the site to review the system configuration and 

discovered a disconnected duct for a second floor register. The duct was repaired and the duct 

system was retested and acceptable post-retrofit leakage rate was confirmed. The cause for the 

disconnected duct was not identified, though it appears to have happened after the retrofit was 

completed, as the leakage rate was the same as was tested at the conclusion of the retrofit work. 

 

9 The blower door test was not able to fully pressurize, therefore the ACH50 was approximated by the equation 

ACH50 = ACHP*(50/P)^0.65 where P is the pressure below 50 Pascal. 
14 

4.3 Annual Energy Use

The monitoring system was installed on September 16, 2011 and data were captured 

continuously over 1 full year with little interruption other than isolated modem connection faults. 

The following discussion compares monitored post-retrofit data with pre-retrofit utility bill data, 

as well as normalization efforts to bring the pre-retrofit data in line with the post-retrofit data and 

also TMY3 “typical” weather conditions. The normalization process is important for a climate 

like Stockton’s, which although characterized as hot-dry, is impacted by changing summer 

weather that can significantly influence annual cooling energy consumption.10 

Figure 4 plots pre-retrofit (sourced from utility bills) and post-retrofit natural gas usage 

(monitored October 2011 through September 2012). In addition to the furnace and water heater, 

the only other appliance that uses natural gas was the range/cooktop, which was calculated as the 

difference between the post-retrofit billed and monitored usage. The range load averaged 1.5 

therms/month and this value was used to update the previous estimate for the pre-retrofit case.11

The graph also shows normalized pre-retrofit gas usage based on the methodology presented in 

Section 3.3. During the summer months, the source of savings is entirely water heating usage, 

with the tankless unit estimated to save approximately 18 therms/month. 

Figure 4. Natural gas usage (pre- and post-retrofit) 

 

10 This effect can be further compounded in households that have higher cooling set points. 11 The original BEopt estimate of appliance + miscellaneous gas usage was 3 therms/month.

0

100

200

300

400

500

600

700

0

20

40

60

80

100

120

140

160

180

October

November

December

January

February

March

April

May

June

July

August

September

Heating Degree Days (65 °F Base) 

Natural Gas (Therms/month)

Natural Gas Usage

Pre Retrofit (Normalized to Post Retrofit Weather) Post Retrofit (Utility Bill)

Post Retrofit Furnace and Water Heating HDD Pre Retrofit

HDD Post Retrofit
15 

Figure 5 plots site electricity usage by month and classification for the pre- and post-retrofit 

billing periods. Cooling energy use was minimal as evidenced by the limited variation in HVAC 

electricity consumption during the year. The garage/spa load represents a significant non-weather 

dependent base load. The garage contains a workshop that is used regularly. Combined with 

house non-HVAC electrical loads, monthly total MEL use varied from 534 kWh to 942 

kWh/month (average of 662 kWh/month). The highest MEL usage in December and January 

stands out and may be attributable to higher consumption associated with the holidays (outdoor 

lights, more cooking, guests, etc.). 

Note that the base load includes a substantial energy use contribution from the spa and the 

garage, which are used regularly. For the post-retrofit monitoring period these loads represented 

almost half of the total base load (gray series in bar chart) and 23% of total house electricity 

(~3,750 kWh). This end use could not be disaggregated in the pre-retrofit data and was not 

targeted in the retrofit work.

Figure 5. Electrical energy usage (pre- and post-retrofit)

Actual and normalized energy costs are summarized in Table 8. The pre-retrofit utility bill data 

are presented in the first column, with the base case weather normalized to the post-retrofit 

monitoring period in the third column. Both pre- and post-retrofit energy use was also 

Garage + Spa House Misc. HVAC

---Pre Retrofit (Utility Bill)

------Post Retrofit

0

200

400

600

800

1000

1200

0

200

400

600

800

1,000

1,200

October

November

December

January

February

March

April

May

June

July

August

September

Electricity (kWh /month)
16 

normalized to TMY3 data for Stockton to approximate a typical year. Utility costs for 

normalized energy use were calculated using the current Pacific Gas & Electric rate schedule as 

of January 2012 (PG&E 2014). These rates vary monthly, ranging from $0.87 to $1.06/therm for 

baseline usage and $1.16 to $1.37 for usage in excess. 

Table 8. Characterization of Pre- and Post-Retrofit Weather, Projected Energy Use, and Costs

PreRetrofit

Pre-Retrofit 

(Normalized 

to PostPeriod)

PostRetrofit Diff. 

Pre-Retrofit 

(Normalized 

to TMY3) 

Post-Retrofit 

(Normalized 

to TMY3) 

Diff. 

Period July 2010

July 2011

October 2011

September 2012

HDD/CDD 2,656/1,135 2,276/1,490 2,494/1,295

Electric 

kWh 10,108 9,870 8,560 1,31

0 9,887 8,511 1,376 

Electric 

Cost $1,988 $2,001 $1,565 $436 $2,013 $1,378 $635 

Gas 

therms 942 826 544 282 882 587 295 

Gas Cost $1,234 $1,036 $633 $403 $1,119 $718 $401

Under a typical year scenario (TMY3) total annual electricity use is projected to decrease by 

14% (1,377 kWh/year) and natural gas use by 33% (295 therms/year). The total electricity cost 

savings were 32% ($636/year), and gas savings of 36% ($402/year). 

Actual monthly source energy use (non-weather normalized) is presented in Figure 6. On an 

annual basis the retrofit achieved 23% source energy savings with respect to the base case. 

Source energy usage was greatest in the winter months due to the higher heating demands. The 

occupants’ use of natural ventilation during the summer months reduced the available savings 

that may have been realized with compressor cooling. The BEopt model shows approximately 

112 annual hours of cooling demand for the retrofit case, down from 667 hours in the pre-retrofit 

case, while the post-retrofit monitoring data reported only 61 hours of cooling demand. 

Pre- and post-retrofit source energy use (normalized to TMY3 data) results are presented in 

Figure 7. On a normalized base, 48 MMBtu in source energy savings are projected. If the garage 

and spa energy is removed from total house energy, the projected savings increase to 29%.

Overall, about one-third of the source energy savings was achieved by the water heater alone, 

saving 23,852 kBtu/year, or 5.5 kBtu/year-dollar spent. The source energy savings attributed to 

the envelope and HVAC upgrades was approximately 24,127 kBtu/year, or 1.02 kBtu/year-dollar 

spent.12 

 

12 Omitting the cost for asbestos removal and like-kind lighting upgrades.
17 

Figure 6. Monthly calculated source energy savings from utility bill

Figure 7. Normalized source energy savings (TMY3)

16%

20%

27% 29% 27%

20%

17% 14%

22% 24% 22% 22%

0%

20%

40%

60%

80%

100%

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

October

November

December

January

February

March

April

May

June

July

August

September

% Source Energy Savings

Source Energy (kBtu)

Billing End Date (month )

 

 

Source Energy Savings (%) Pre-Retro Post-Retro

84.8

40%

92.7

44%

32.3

16%

Pre Retrofit

Source Energy Usage 

(209 MMBtu/Year)

60.6

29%

92.7

44%

8.5

4%

48.0

23%

Post Retrofit 

Source Energy Usage

(162 MMBtu/year)

HVAC

House Base Load 

+ Garage/Spa

Water Heating

Savings
18 

4.4 Project Economics 

During the course of the monitoring period, DEG acquired pre-and post-retrofit utility bills, 

which were used in conjunction with the monitored data to revise the BEopt model base 

assumptions. The simulation reported a much higher space conditioning load, based on standard 

BEopt assumptions. The thermostat schedules were adjusted to match actual set points employed 

by the owner, yet the model still overpredicted the heating and cooling loads. The difficulties in 

reconciling the model with monitored performance are due in part to the DOE-2 and EnergyPlus 

simulation tools’ difficulty in accurately modeling heat transfer through uninsulated exterior 

walls. The space heating energy use estimated in the model was nearly twice that observed. 

The GHS standard retrofit package does not typically include HVAC replacement; however, in 

order to better align the savings with the retrofit measures, a pre-retrofit case with a standard 

HVAC replacement was simulated with BEopt. The simulation results, which overpredicted 

heating and cooling loads, were then adjusted using monitoring and utility bill data to obtain a 

better estimate of performance. This pre-retrofit case with a standard HVAC was used to 

determine the project economics presented in Tables 8 and 9.

Table 9. Projected Savings and Cost Effectiveness

Capital Cost $23,756 Electricity

(kWh)

Gas 

(therms)

Savings 

($) 

Annual 

Cash 

Annualized Cost $944 Flow

Post-Retrofit Energy Savings

(normalized to monitoring period

weather)

1,310 282 $893 ($105) 

Estimated Average Energy Savings

(normalized to TMY3 weather13) 887 284 $837 ($107) 

The incremental total project cost was $23,756 (after incentives and excluding standard HVAC 

upgrade cost and asbestos abatement), which financed over 30 years at a 4.5% interest rate 

amounts to an annualized cost of $944/year. The projected energy savings are presented in Table 

9. The realized energy savings is based on a direct comparison of utility bills, in which the utility 

savings were $1,025. The weather was only slightly warmer in the winter following the retrofit 

and substantially warmer in the summer, therefore the weather normalized comparison of the 

pre- and post-retrofit utility bills resulted in even less savings than was expected. Finally, the 

pre- and post-retrofit usage patterns were normalized to TMY3 to determine “typical year” 

savings of approximately $837/year. 

While the existing HVAC system needed to be replaced, the selection of a two-speed furnace and 

a 16 SEER air conditioner was not determined to be cost effective. BEopt models were run for a 

comparison of the energy impacts of selecting a minimum code-compliant furnace and 

condensing unit, which showed that the high efficiency unit contributes only 3% to site energy 

savings, or approximately 3.2 MBtu/year over the code-compliant model. 

The package selected for this retrofit was one of several packages being offered by GHS to 

neighborhood retrofits. The measures included in the standard package (described in Section 1.1) 

 

13 Assumes pre-retrofit case with code-compliant HVAC unit. 
19 

did not include replacing the existing windows or insulating the floor. The total for the GHS 

standard package is $9,456 with $2,750 in incentives, making the installed cost $6,706. The 

annualized cost for the standard package is $266 (if financed at 30 years and 4.5%). The updated 

BEopt model was simulated with the standard retrofit package to provide a base from which to 

determine the incremental savings associated with the whole-house retrofit. The base package 

would have achieved about 27% of the whole-house retrofit package source energy savings, with 

most of the reduction in space heating costs. While neither the base package nor the retrofit was 

cost effective, the base package would have saved $196 of the pre-retrofit annual utility costs. 

The additional measures needed to quadruple the energy savings come at a cost that surpasses 

the benefit, most significantly the window package and water heating change. Table 10 compares 

the annualized cost and savings for the standard and whole-house retrofit packages.

Table 10. Comparison of Standard and Whole-House Retrofit Package Savings and Economics

Model Annualized 

Cost ($) 

Source Energy 

Savings (MBtu)

Savings 

($) 

Annual 

Cash Flow

Base Package $266 11.1 $196 ($70)

Whole-House Retrofit 

Package $944 41.6 $837 ($107)

Difference $678 30.5 $641 $37

4.5 Homeowner Feedback

The homeowner was surveyed at the conclusion of the monitoring period to ascertain overall 

satisfaction and the perceived change in comfort related to retrofit measures. During the initial 

proposal for work, the homeowner expressed discomfort with the upstairs rooms, specifically 

that they were too warm in the summer. Although comparative pre-retrofit data weren’t 

available, a temperature and humidity sensor was installed upstairs and downstairs after the 

retrofit to evaluate comfort. According to ASHRAE Standard 55, there exists a range of 

temperature and humidity at which 80% of sedentary or slightly active people would find the 

environment comfortable. The ranges, as shown in Figure 8 and Figure 9, are defined by clothing 

level, where 1 clo is equivalent to a winter business suit, and 0.5 clo is equivalent to short sleeves 

and trousers, representing summer comfort. 

Throughout the heating season (from the middle of October to the middle of April), 95% of the 

time the first floor is within the acceptable range; less than 1% of the time temperatures were 

lower than the comfort range. The second floor is often warmer than the comfort range due to 

thermal stratification and the fact that the thermostat is located on the first floor. In the summer 

(Figure 8) nearly half the time the temperatures exceeded standard comfort levels; however, the 

homeowner considers the home to be more comfortable, and set the thermostat to a higher set 

point, than prior to the retrofit. Overall the difference in the first and second floor temperatures 

during the summer months was less than 2°F. 
20 

Figure 8. Winter comfort levels

Figure 9. Summer comfort levels

CLO 0.5

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

50 60 70 80 90 100

Humidity Ratio (lbw/lbda)

Dry Bulb Temperature (°F)

Zone1

Zone2

First Floor

Second Floor

CLO 1.0

CLO 0.5

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0.0160

0.0180

0.0200

50 60 70 80 90 100

Humidity Ratio (lbw/lbda)

Dry Bulb Temperature (°F)

Zone1

Zone2

First Floor

Second Floor

CLO 1.0
21 

Specific questions to the homeowner were targeted to determine any pre-/post- retrofit 

behavioral changes, including occupancy, water heating usage patterns, and thermostat settings. 

No occupancy pattern changes between the pre-retrofit and post-retrofit periods were noted. 

Questions were posed to determine any sensitivities with respect to water heating time lag, flow 

sensitivity, and cold-water sandwich behaviors that are commonly experienced with tankless 

water heaters and known to affect usage. The homeowners had a recirculation pump installed to 

minimize the wait times normally experienced when tankless units are installed in large branch 

distribution systems. Overall the homeowners reported no significant behavioral influences that 

would affect energy consumption. The homeowners did note that they were less inclined to 

adjust the thermostat set points after the retrofit, an indicator that the house remains more 

comfortable. The full homeowner survey report is included in the Appendix. 
22 

5 Conclusions and Recommendations

1. Are there measured savings and homeowner comfort benefits resulting from whole-house 

retrofits that may motivate homeowners to invest more in whole-house retrofits as 

opposed to more standard? 

Overall the whole-house retrofit package implemented at the Stockton, California, site 

demonstrated 23% source energy savings with respect to the prior year’s TMY3 normalized 

utility bills. The energy savings were largely due to projected water heating savings, as well as 

reductions in heating energy use due to load impacts from envelope and duct sealing, increased 

ceiling and floor insulation, and improved furnace efficiencies. Cooling savings were minimal 

due to a combination of it being in a moderate climate and the occupants having fairly low 

cooling demands. 

The preliminary BEopt model projected 47% source energy savings; however, it overestimated

the heating and cooling loads in comparison with what was experienced, likely due to how the 

software handles uninsulated exterior and transitional walls. The BEopt model was adjusted 

using monitored data and reported thermostat schedules to determine the proportion of savings 

attributed to the whole-house retrofit package over the base package. The base package is 

estimated to have achieved 8% source energy savings (normalized to TMY3) over prior year 

utility bills ($196 projected annual utility bill savings). The whole-house retrofit package is 

projected to save an additional 15% in source energy savings with a corresponding savings in 

utility bills of an additional $641/year. 

The financed annualized cost of the whole-house retrofit ($944) exceeded the projected energy 

savings ($837). This was largely due to the inclusion of an expensive window upgrade 

(~$11,000) and an expensive tankless water heater retrofit ($4,400). The standard package was 

also not cost effective, with an annualized cost of $266 and a projected utility savings of 

$196/year. The window upgrade improved occupant comfort and increased the perceived value 

of the house, both of which were desired by the homeowner. However, from a cost effectiveness 

perspective, window retrofits are very hard to justify through energy savings in mild climates 

such as Stockton’s. With whole-house retrofits in many climates, the homeowner will need to 

make value assessments about which measures to add beyond a basic package that will increase 

overall performance, although the economic justification may not be strong. 

Overall savings were much lower than projected in the original BEopt model for a variety of 

reasons. Cooling energy use and the resulting savings were much lower than projected. In 

addition miscellaneous electrical consumption (house loads, garage, and spa) amounted to 

~7,000 kWh/year. This report highlights the complexities of achieving energy savings on 

projects where miscellaneous end uses represent nearly half of the household source energy use

and opportunities to reduce those loads are not addressed.

2. What energy upgrade strategies are most effective (in terms of cost and energy savings) 

in whole-house retrofit projects? 

Whole-house retrofits combine a standard package of measures that represent the most costeffective options, with additional measures that balance the desires and budget of the 

homeowner, site constraints, and the recommendations of the participating building performance 
23 

contractor. For each individual project, this can be an imprecise process which brings less costeffective measures into play to satisfy homeowner preferences and project constraints. In the 

case of the Stockton house, the Standard Package of measures was found to reduce pre-retrofit 

source energy consumption by 8% while the annualized cost was slightly higher than the 

savings. The whole-house retrofit, which included new windows ($11,000) and a tankless water 

heater retrofit ($4,400), resulted in a 15 percentage point increase in savings (from 8% to 23%) 

relative to the standard package, but the annualized homeowner cash flow decreased from a 

negative $70/year, to $107 a year. Neither windows nor a gas tankless water heater retrofit are 

considered cost-effective retrofit measures in relatively mild climates14 and low occupant loads 

as seen with this retrofit. The moderate summer climate and high cooling set points utilized in 

the house also minimized the expected cooling energy savings associated with the high SEER 

equipment. 

The variability in impacts for a whole-house retrofit package is highly dependent on the selected 

measures, the climate, the characteristics of the house, and how the occupant interacts with the 

house. In most cases, the occupant will influence the selection of measures based on areas of 

concern, aesthetic desires, and budget constraints. For a whole-house retrofit to be successful, it 

should both make measurable reductions in energy use and be cost effective. In the case of the 

Stockton project the selected whole-house retrofit measures improved the annual savings, but did

not improve the overall package cost effectiveness. 

 

14 Windows due to the mild climate and tankless water heater due to gas line and venting upgrade costs.
24 

References 

ACCA (2006). Manual J. HVAC Residential Load Calculation, 8th Edition. Arlington, VA: Air 

Conditioning Contractors of America. 

ASHRAE. ANSI/ASHRAE Standard 55-2010 “ Thermal Environmental Conditions for Human 

Occupancy.” Atlanta GA: American Society of Heating, Refrigerating and Air-Conditioning 

Engineers, Inc. 

Berman, M.; Smith, P.; Porse, E. (2012). Evaluation of Retrofit Delivery Packages. Prepared for 

Building America, Building Technologies Program by the Alliance for Residential Building 

Innovation, December.

DOE. (2010a). “Case Study: SMUD’s Energy Efficient Remodel Demonstration Project – Fair 

Oaks, CA.” Building America Comprehensive Energy Retrofit – Efficient Solutions for Existing 

Homes. October, 2010. PNNL-SA-76139. 

DOE. (2010b). “Case Study: SMUD’s Energy Efficient Remodel Demonstration Project – 

Sacramento, CA.” Building America Comprehensive Energy Retrofit – Efficient Solutions for 

Existing Homes. October, 2010. PNNL-SA-75681. 

Fairey, P.; Parker, D. (2012). Cost Effectiveness of Home Energy Retrofits in Pre-Code Vintage 

Homes in the United States. Prepared for Building America, Building Technologies Program by 

Building America Partnership for Improved Residential Construction, November.

Kok, N.; Kahn, M. (2012). The Value of Green Labels in the California Housing Market. 

Accessed June 2014. 

www.usgbc.org/sites/default/files/ValueofGreenHomeLabelsStudy_July2012.pdf. 

PG&E (2014). Tariff Book. Accessed June 2014. www.pge.com/tariffs/ERS.SHTML.

PNNL. (2009a). “Case Study: Green Home Solutions by Grupe – Lodi, CA.” Efficient Solutions 

for Existing Homes – Home Performance with ENERGY STAR Case Study. September. PNNLSA-68406. 

PNNL. (2009b). “Case Study: HartmanBaldwin Design/Build – Pasadena, CA.” Efficient 

Solutions for Existing Homes – Home Performance with ENERGY STAR Case Study. 

September. PNNL-SA-68405. 
25 

Appendix: Homeowner Survey
26 
27 
28 

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