Occupant-in-Place Energy 

Efficiency Retrofit in a 

Group Home for 30% Energy 

Savings in Climate Zone 4

Mike Moore

Building America Partnership for Improved 

Residential Construction

August 2013
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iii

Occupant-in-Place Energy Efficiency Retrofit in a Group Home for 

30% Energy Savings in Climate Zone 4

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: 

Mike Moore

Newport Partners, LLC.

of the

Building America Partnership for Improved Residential Construction (BA-PIRC)

Cocoa, FL 32922

NREL Technical Monitor: Stacey Rothgeb

Prepared under Subcontract No. KNDJ-0-40339-03

August 2013
iv

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v

Contents

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

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

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

Executive Summary................................................................................................................................. viii

1 Problem Statement............................................................................................................................... 1

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

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

1.3 Relevance to Building America’s Goals..............................................................................2

1.4 Cost Effectiveness Relative to Energy Savings...................................................................2

1.5 Tradeoffs and Other Benefits...............................................................................................3

2 Experiment ............................................................................................................................................ 6

2.1 Research Questions..............................................................................................................6

2.2 Technical Approach.............................................................................................................6

2.3 Retrofit Measures and Results.............................................................................................7

2.3.1 Building Airtightness...............................................................................................7

2.3.2 Duct Tightness.........................................................................................................9

2.3.3 Appliance and Plug Loads Energy End Use and Savings......................................10

2.3.4 Air Source Heat Pump Energy End Use ................................................................13

2.3.5 Indoor Temperatures..............................................................................................15

2.3.6 Domestic Hot Water Consumption........................................................................16

2.3.7 Ventilation..............................................................................................................18

2.3.8 Window Operation.................................................................................................19

3 Analysis ............................................................................................................................................... 22

3.1 Building Energy Simulations.............................................................................................22

3.2 Building Energy Use—Utility Bills and End Use Disaggregation....................................24

3.2.1 Post-Retrofit Energy Savings.................................................................................24

3.2.2 Post-Retrofit Energy End Uses..............................................................................24

3.3 Cost Effectiveness..............................................................................................................25

4 Conclusion .......................................................................................................................................... 29

5 References .......................................................................................................................................... 32

Appendix A. ASHRAE 62.2-2010 Whole-House Mechanical Ventilation Calculations....................... 33

Appendix B. Calculation of Minimum Dynamic Equivalent Leakage Area ......................................... 35

Appendix C. Floor Plan of Sasha Bruce Group Home .......................................................................... 37
vi

List of Figures

Figure 1. Sasha Bruce Home, rear ............................................................................................................ 1

Figure 2. Sasha Bruce Home, front: center and right units.................................................................... 1

Figure 3. Exposing a hidden fireplace and flue ....................................................................................... 7

Figure 4. Air sealing in the attics with limited clearance........................................................................ 8

Figure 5. Kitchen and hallway average dry-bulb temperature profile during the month of February15

Figure 6. Thermostat “cheat sheet” provided for the building staff.................................................... 16

Figure 7. Window state sensor................................................................................................................ 19

Figure 8. Effect of window operation (during hours with ASHP cycles) on building ELA at various 

outdoor to indoor temperature differentials .................................................................................... 21

Figure 9. Total energy use (pre- and post-retrofit) and disaggregated energy use (post-retrofit 

only) as a function of outdoor dry-bulb temperature ..................................................................... 25

Unless otherwise noted, all figures were created by BA-PIRC.

List of Tables

Table 1. EER Measures............................................................................................................................... 4

Table 2. Building Leakage: Blower Door Test Results............................................................................ 9

Table 3. Duct Leakage Test Results........................................................................................................ 10

Table 4. Annual Appliance and Plug Load Energy Consumption, Modeled Versus In-Situ.............. 11

Table 5. 11-Month Monitoring Period Appliance and Plug Load Post-Retrofit Energy Consumption12

Table 6. Post-Retrofit Normalized ASHP Energy Use, Heating, and Cooling ..................................... 14

Table 7. DHW Gallons and Energy Use................................................................................................... 17

Table 8. Ventilation Location and Flow Rates........................................................................................ 18

Table 9. Pre-Retrofit Mechanical Equipment Performance Assumptions........................................... 22

Table 10. Building Envelope Modeling Assumptions ........................................................................... 23

Table 11. Estimated Annual Site Energy, Initial and Revised Simulations ......................................... 23

Table 12. Investment Cost of Retrofit Measures.................................................................................... 27

Unless otherwise noted, all tables were created by BA-PIRC.
vii

Definitions

ASHP Air source heat pump

CFM Cubic feet per minute

CDH Cooling degree hour, base 74

DHW Domestic hot water

ECM Energy conservation measure

EER Energy efficiency retrofit

EF Energy factor

ELA Equivalent leakage area

HDD Heating degree day, base 65

HSPF Heating season performance factor

IAQ Indoor air quality

SEER Seasonal energy efficiency ratio

SIR Savings to investment ratio
viii

Executive Summary

Energy efficiency retrofits (EERs) face many challenges on the path to scalability. Limited 

budgets, limited accessibility of envelope penetrations, cost effectiveness, and risk factors impact 

the type and the extent of measures that can be implemented feasibly to achieve energy savings 

goals. Group home retrofits can face additional challenges to those encountered in single-family 

homes, such as reduced access (occupant-in-place restrictions) and lack of incentives for 

occupant behavioral change. 

Building owners, operators, and other groups need to have a firm grasp on the feasibility and cost 

effectiveness of EERs to group homes. These stakeholders also need guidance regarding

common risk factors and the potential impact on energy retrofit measures in addition to the 

impact of occupant behavior on building energy use. This is particularly the case for older 

buildings.

This project studies the specification, implementation, and energy savings from an EER in a 

group home, with an energy savings goal of 30%. This final report chronicles the retrofit 

measures specified, their cost effectiveness based on pre-retrofit and post-retrofit utility bill 

analysis, and the test results that were used to characterize pre-retrofit and post-retrofit 

conditions.

The following energy conservation measures were implemented on the group home:

• 17.55 seasonal energy efficiency ratio, 8.8 heating season performance factor air source 

heat pump (ASHP)

• Electric water heater, 0.92 energy factor

• R-49 ceiling insulation

• Air sealing, as accessible

• Aerosolized duct sealing

• Partial window replacement

• ENERGY STAR® refrigerator, freezer, dishwasher, and clothes washing machines

• Programmable thermostats

• Lighting occupancy sensors.

Significant findings include:

• Sensors installed to monitor the operation of 32 windows and one door showed up to a 

19% increase in the minimum dynamic effective leakage area of the building as a result 

of window openings during hours when the ASHP recorded a cycle. This points to an 

opportunity to further reduce energy use through future adjustments to occupant behavior 

(i.e., through reducing window openings during ASHP operation).
ix

• Replacement of ASHPs identified and addressed a risk factor that existed in the preretrofit home, which in this case was improper condensate drainage that had resulted in 

more than 4 in. of water accumulating in one unit’s return plenum. 

• While air sealing measures may typically garner a 30% reduction in infiltration rates in 

weatherized dwellings (Blasnik 2007), unless specific, accessible measures are identified 

and targeted prior to the retrofit, more conservative estimates should be made for older, 

attached buildings with potential air sealing accessibility issues. A 10% improvement 

expectation is more reasonable given that certain areas may be inaccessible and certain 

retrofit measures may be impractical due to restrictions such as project budget or 

occupancy during construction.

• Based on utility bill data and onsite monitoring of major end loads, the overall savings to 

investment ratio of the combined retrofit measures over a 10-year time horizon was found 

to be 2.4.
1

1 Problem Statement

1.1 Introduction

This project identifies and documents the installation and performance of cost-effective measures 

for an occupant-in-place energy efficiency retrofit (EER) in a group home in inner city 

Washington, D.C., called the Sasha Bruce Home. Retrofit measures that were pursued included 

minimally invasive air sealing, improved ceiling insulation, duct sealing, appliance replacement, 

high efficacy lamps, improved lighting controls, and mechanical system replacement. 

Short-term data were gathered through building diagnostic tests of duct systems and building 

airtightness. Long-term data were collected on overall performance of measures, cost

effectiveness, percent of energy consumed by various end uses, and occupant behavior. This

research effort builds upon the current body of knowledge of retrofits, specifically occupant-inplace group home retrofits. 

1.2 Background

Recent focus of Building America teams is resulting in more information on cost-effective EERs

of 30% or greater energy savings for multifamily buildings. Examples include retrofits of largescale cold climate apartments (Neuhauser et al. 2012), and forthcoming research on mixed 

climate dwellings (Building America teams NAHBRC-IP’s 

Greenbelt and BA-PIRC’s Bay Ridge retrofits) and hot-humid 

dwellings (NAHBRC-IP’s Fort Benning retrofit). Three of 

these studies address retrofits in occupied units. The Sasha 

Bruce Home differs from these previous studies in that it is a 

group home composed of two attached inner city row houses. 

Group homes have characteristics of both multifamily (e.g., 

high occupancy) and single-family dwellings (e.g., common 

bathrooms and kitchen), and are covered within the scope of 

the International Building Code, where they are recognized as 

R-4 occupancies. Built in 1900, the home houses variable, 

short-term youth occupants who have little to no motivation 

to save energy. The home includes six bedrooms that house 

up to eight occupants, three active offices for up to five staff, 

five bathrooms 

(two with 

active bathing 

facilities), three 

recreational or TV areas, and a kitchen that is used 

very heavily to prepare three meals per day for 

occupants and staff. A floor plan of the unit may be 

found in Appendix C. Utilities are paid by the 

owner, and pre-retrofit annual electricity bills for 

the all-electric 4,392 ft2 building are extremely 

high—in excess of $11,000. Annual energy use 

intensity was high as well, at 65 kBtu/ft2. 

Figure 2. Sasha Bruce Home, 

front: center and right units

Figure 1. Sasha Bruce Home, rear
2

Prior to the retrofit, the aged home’s appliances and equipment were reaching the end of their 

useful lives, with most equipment and appliances in need of replacement. The advanced age of 

the equipment was a key to making the EER more attractive from an economic perspective. (See 

Section 3.3 for more details.) Funds and support for the retrofit were contributed by Walmart, 

HomeAid, and the Home Builder’s Care Foundation. While a full shell retrofit would have been

an attractive research project, the building owner, Sasha Bruce Youthwork, faced practical 

limitations on the use of the funds, and was required to ensure that, at a minimum, the aging 

equipment and appliances were replaced. Remaining funds were used to improve the building 

envelope, reduce the air infiltration, install high efficacy lighting, reduce hot water consumption, 

and improve lighting controls.

1.3 Relevance to Building America’s Goals

Within existing homes, the goal of the U.S. Department of Energy’s Building America program 

is to reduce energy use by 30%–50% versus pre-retrofit conditions. To this end, Building 

America teams conduct research to advance market-ready energy efficiency solutions in homes 

across climate zones, with consideration given to improving comfort, safety, and durability.

Building America’s energy savings goals are particular to individual climate zones. The project 

site is located in Washington D.C., in a mixed-humid climate. As related to existing homes 

within mixed-humid climates, Building America has a goal of 30% energy savings from the preretrofit condition by 2013. This EER sought to achieve this goal by specifying a set of retrofit 

measures expected to provide a minimum of 30% energy savings in the 2011–2012 time frame. 

A wide breadth of measures were applied to achieve this target, including improvements to or 

replacements of mechanical equipment and distribution systems, appliances, lighting and lighting 

controls, the building envelope, and hot water conservation measures. 

The results are expected to provide valuable information on the cost effectiveness of retrofit 

measures to the building owner, who owns and manages several similar properties in the area, as 

well as be directly applicable to hundreds of other group homes that operate within the same 

climate zone. 

1.4 Cost Effectiveness Relative to Energy Savings

Recommended EER measures were assessed and prioritized based on cost effectiveness relative 

to predicted energy savings. Installed costs were recorded, and energy modeling with REM/Rate 

was conducted to project the cost effectiveness of various measures on the basis of savings to 

investment ratio (SIR, which is highly relevant to multifamily projects that receive 

weatherization funding) and other metrics. The SIR can be defined as the present value of 

savings over a given time relative to the incremental cost of the measure. BEopt software was 

also evaluated for this task, but was ultimately bypassed due to lack of functionality in several 

key areas; more detail is provided in Section 3.1. As is typical in the industry, a SIR of ≥ 1.0 

was considered to be cost effective within the confines of this project.

Equipment and appliances that were near the end of their useful lives were assumed to require 

replacement, in which case, the costs associated with the measures were taken as the incremental 

cost between an energy-efficient replacement and a baseline, standard efficiency replacement

plus the residual value of the existing equipment or appliance. Residual value of existing 

equipment was calculated as the cost of a new standard efficiency replacement, depreciated
3 

linearly with the age of the equipment, until it reached a value of zero at the equipment’s useful 

life, as determined by industry sources. 

Estimates of energy savings associated with selected retrofit measures were made using building 

energy simulations and were refined with data from short-term testing. Long-term monitoring of 

utility bills and individual end uses confirmed energy savings. 

1.5 Tradeoffs and Other Benefits

Targeted retrofit measures were identified through REM/Rate building energy simulations. 

Initial REM/Rate simulations were completed by modeling individual measures separately, but 

final simulations included the projected energy savings of multiple combined measures. 

The final measures, listed in Table 1, were selected by the building owner, who had additional 

concerns besides maximizing cost effectiveness, such the desire to replace as much equipment as 

possible while funds were available. Hence, some moderately efficient equipment was replaced 

prior to the end of its useful life (e.g., a 13 seasonal energy efficiency ratio [SEER]/7.7 heating 

season performance factor [HSPF] heat pump that was only 3 years old). However, because the 

building, equipment, and appliances were in a general state of disrepair, some of the measures 

were necessitated by the age of the equipment (such as replacement of a 19-year-old air source 

heat pump [ASHP]). When possible, higher efficiency appliances and equipment were selected 

for replacement. All considered, cost effectiveness for the project was still demonstrated by 

maintaining a SIR ≥ 1.0. 

Advanced controls, such as programmable thermostats and lighting occupancy sensors, were 

expected to not only reduce energy used at the home, but also to improve the building owner’s 

ability to control the energy used by short-term occupants. Aerosolized duct sealing was

specified to improve the supply of conditioned air to registers throughout the home, providing a 

more comfortable environment and perhaps reducing the impetus for occupants to open windows 

during the operation of the ASHPs from any overheating or undercooling of zones. 
4 

Table 1. EER Measures

Item Category Retrofit Measure

Reasons for 

Retrofit 

(E,A,O)**

Pre-Retrofit Measure

1 Space 

heating/cooling

ASHP: 17.55 SEER, 8.8 HSPF with 

electric resistance backup O, E

ASHP: 3 years old. Rating when new: 13 

SEER, 7.7 HSPF. Adjusted ratings*: 11.9 

SEER, 7.0 HSPF. Electric resistance 

backup. 

2 Space 

heating/cooling 

ASHP: 17.55 SEER, 8.8 HSPF with 

electric resistance backup E, A

ASHP: ~19 years old. Rating when new: 

10 SEER, 6.8 HSPF. Adjusted ratings*: 

5.6 SEER, 4.0 HSPF. Electric resistance 

backup. 

3 Water heating Electric water heater 50 gal., 0.92 

energy factor (EF) A, E Electric, 80 gal, 15 years old. Rating when new: 0.82 EF. Adjusted rating*: 0.8 EF. 

5 Refrigerator ENERGY STAR qualified O, E 5 years old, non-ES qualified

5 Freezer ENERGY STAR qualified O, E 3 years old, non-ES qualified

6 Clothes washer 1 ENERGY STAR qualified A, E 18 years old, non-ES qualified

7 Clothes washer 2 ENERGY STAR qualified A, E, O 9 years old, non-ES qualified

8 Dishwasher ENERGY STAR qualified E, O 6 years old, non-ES qualified

9 Thermostat 1 Programmable thermostat compatible 

with ASHP E, A Mercury thermostat

10 Thermostat 2 Programmable thermostat compatible 

with ASHP E, A Mercury thermostat

11 

Lighting—

occupancy/motion 

sensor

Occupancy sensors in two recreation 

rooms and one dining room (6 sensors 

total)

E No occupancy sensors 

12 Windows 

Replace all 18 windows on the front of 

the building to meet 2012 International 

Energy Conservation Code 

requirements (U-0.32) 

E, A, O 

Vinyl, double-pane. 12 years old. Leaky, in 

poor operating condition. Assume U = 0.5, 

SHGC = 0.62, per ASHRAE Fundamentals 
5 

Item Category Retrofit Measure

Reasons for 

Retrofit 

(E,A,O)**

Pre-Retrofit Measure

13 Luminaires 0% of luminaires are incandescent E 25% of luminaires are incandescent

14 Permanent 

lighting fixtures

Replace up to 10 permanent lighting 

fixtures as needed. A, O Multiple lighting fixtures broken

15 Attic insulation Install loose fill cellulose insulation in 

the attic to reach R-49. E R-19 

16 Duct sealing Aerosolized duct sealing to reduce 

leakage to outside E Leaky. See Table 3. 

17 Air sealing Caulk/foam all accessible 

interior/exterior penetrations E Leaky. See Table 2. 

18 Water reduction 2 low-flow shower heads (2.2 gpm); 

5 aerator faucets (2.0 gpm) E 2.5 gpm shower heads;

2.2 gpm faucets 

19 Clothes dryer 1 Clothes dryer with moisture sensor O No moisture sensor

20 Clothes dryer 2 Clothes dryer with moisture sensor O No moisture sensor

Table 1 Notes: *Adjusted ratings are a factor of age and maintenance per Building America protocol (Hendron and Engebrecht 2010). **Reasons for Retrofit: 

Expected energy savings, “E”; Advanced age of equipment or poor operating condition, “A”; Owner preference, “O”.
6

2 Experiment

2.1 Research Questions

The following primary research questions were answered within this project:

• What is the post-retrofit energy use of various end use loads in this group home (i.e., 

space heating and cooling, water heating, laundry, food storage, offices, entertainment 

center, etc.); and what percent of the total building energy use is accounted for by the 

energy end use categories that were monitored?

• What are the estimated annual energy savings from the retrofit based on data collected 

over the monitoring period?

• What SIR is expected for an EER with a 30% energy savings target?

• What are the challenges and solutions to making the retrofit packages replicable on 

similar building types? 

• How does the occupant operation of windows affect the building airtightness during the 

operation of the ASHP?

Ancillary research questions answered within this project included the following:

• Based on short-term tests, were targeted airtightness levels achieved, and if not, why?

• How effective is aerosolized duct sealing at reducing total duct leakage?

• Can thermostat setbacks be employed to save more energy?

• What is the typical pre- and post-retrofit hot water consumption? What are the expected 

energy savings associated with replacement of the large, old water heater with a new, 

smaller water heater?

• Using Appendix A of ASHRAE 62.2, what are the recommended local exhaust flow rates 

and whole house ventilation rates for acceptable indoor air quality (IAQ)?

As they pertain to individual retrofit measures, primary research questions are addressed in 

Sections 2.3, 3.2, and 3.3 and then summarized within the Conclusion in Section 4. Additional, 

ancillary research questions that are specific to individual retrofit measures are listed and 

addressed within Section 2.3.

2.2 Technical Approach

Building energy simulations of pre- and post-retrofit scenarios were used to estimate energy 

savings. Both pre- and post-retrofit short-term tests and data analysis were used to gauge the 

performance of the home in relation to the prescribed retrofit measures. Schedule and resource 

constraints limited the period of pre-retrofit data collection. Prior to retrofit, some parameters 

were monitored for a period of 3 weeks, whereas others were monitored for only 8 days. Longterm monitoring occurred over a period of 11 months. This was deemed to be a sufficient length 

of time to accurately characterize performance given the excellent curve fit of post-retrofit 

whole-building energy use as a function of outdoor dry-bulb temperature. (See Section 3.2 and 
7

Figure 9 for more information.) Across both pre-retrofit and post-retrofit periods, diagnostic tests 

and monitoring included the following:

• Building airtightness: Blower door test with two Model 3 Minneapolis Blower Doors and 

DG-700 Digital Gauge. See Section 2.3.1.

• Bathroom ventilation flow rate: Test using the Exhaust Fan Flow Meter from The Energy 

Conservatory. See Section 2.3.6; pre-retrofit only.

• Duct leakage: Duct leakage test using the Minneapolis Duct Blaster and DG-700 Digital 

Gauge. See Section 2.3.2.

• Hot water use: Short-term and long-term monitoring of hot water gallons using Jerman 

Company’s DLJ-SJ75C meter with Onset UX120-017M data logger.

• Indoor temperature and relative humidity: Short-term and long-term monitoring of indoor 

thermal conditions using Onset U10-003s at the following locations: East basement: TV 

room (ceiling); West basement: unused storage room (ceiling); First floor: laundry/west 

thermostat (wall), kitchen (ceiling), east hallway at thermostat (wall); Second floor: east 

bathroom (ceiling), hallway (ceiling), west bathroom (ceiling). 

• Appliance energy use: 

o Refrigerator, freezer, and washing machines: Short- and long-term monitoring of 

appliance energy use (kWh) with P3 International Kill-A-Watt EZ meters.

o Clothes dryer, water heater, ASHP compressor, electric resistance backup, and 

fan: Short- and long-term monitoring of appliance energy use (kWh) with CCS’ 

WNB-3Y-208-P Watt Node with associated current transducers and Onset 

UX120-017M data logger.

2.3 Retrofit Measures and Results

Short- and long-term tests results are grouped according to category impacted and include a 

narration of the retrofit measure pursued as well pre- and post-retrofit test results where 

applicable. 

2.3.1 Building Airtightness 

In an old, leaky home, air sealing of the envelope can 

be expected to result in about a 30% reduction in 

infiltration (Blasnik 2007), and is commonly viewed 

as one of the most cost-effective retrofit measures. 

Similar expectations were held for this home, but the 

final implementation of air sealing fell far short of 

this goal due to limitations in scope, budget, and 

accessibility of envelope penetrations. 

Ancillary Research Question: Based on short-term 

tests, were targeted airtightness levels achieved, and if 

not, why?

Figure 3. Exposing a hidden fireplace and flue
8

The original retrofit scope called for sealing of the three chimneys that were visible from the 

exterior of the building. This was to be accomplished by sealing the one visible fireplace from 

the interior and then removing drywall as required to find and seal the two additional fireplaces,

also from the interior. Prior to the retrofit, there was no attic access, but when an attic access 

hatch was created during the retrofit, a fourth chimney was discovered. When first-floor drywall 

was removed to reveal what was hidden behind, the retrofit crew soon realized that the home 

housed not three, but 16 fireplaces, with four fireplace flues routed to each chimney. The retrofit 

crew was able to seal three of the fireplaces flues from within the home, and four additional 

fireplace flues within the attic. Flues were stuffed with bags of insulation and then air sealed with 

spray foam. 

The remaining nine flues, each measuring approximately 12 in. × 12 in., were not sealed, 

because the project did not have sufficient funds within its scope to accomplish this work, nor 

the personnel qualified to access and seal chimneys from the exterior. As a result, most of the air 

sealing efforts occurred in the attic, including capping and sealing around noninsulation contact 

rated recessed lights and foaming at top plates and around light boxes and abandoned chimney 

chases. (See Figure 4.) This work was highly labor intensive, due to limited clearance in one of 

the attics and the need to move pre-existing batt insulation to access penetrations. 

Figure 4. Air sealing in the attics with limited clearance

2.3.1.1 Short-Term Test Results

Pre- and post-retrofit short-term blower door tests revealed significant improvements from the air 

sealing (a reduction of 935 CFM 50 and improvement of 7%), but the reduction fell far short of 

the typical 30% improvement in air sealing inferred from weatherization agency data (Blasnik 

2007). Given the challenges often presented by group and multifamily buildings and the fact that 

the Blasnik reference did not differentiate between single family, multifamily, attached, or 

detached buildings, our initial target was a more conservative 20% improvement in air sealing.

The unique characteristics of this building that were discovered during the retrofit process (i.e., 

16 flues, 9 of which were inaccessible) would have ultimately required greater funding than was 

available to fully leverage the potential air sealing improvements. Achieving a 7% improvement 

in airtightness instead of a 20% improvement resulted in an approximate 4% reduction in 

projected whole-building energy savings. (See Section 3 for more details.)
9 

Table 2. Building Leakage: Blower Door Test Results

Leakage Pre-Retrofit Post-Retrofit Reduction Diagnostic 

Equipment

CFM@50 Pa 12,716 11,781 935 Blower Door

ACH@50 Pa 22.2 20.6 1.6 Blower Door

 

The modest reduction in air infiltration achieved during this retrofit project is not atypical, 

especially in older group homes or multifamily buildings. Reasons include limited budgets, 

limited work scope due to occupant-in-place conditions, inability to fully investigate the building 

and identify all deficiencies, and limitations in the skills of the available workforce. It is also true 

that a few very large leakage pathways will dominate, and unless those can be accessed, it will 

be difficult to realize significant improvement.

2.3.2 Duct Tightness

Two old, leaky central duct systems offered a good opportunity for energy savings and improved 

comfort. Because the ducts were inaccessible, aerosolized duct sealing was specified to seal the 

ducts. All ducts were located within conditioned space. 

Ancillary Research Question: How effective is aerosolized duct sealing at reducing total duct 

leakage?

Aerosolized duct sealing began with a thorough duct cleaning to ensure that aerosolized particles 

would be able to adhere to the duct walls. Next, supply registers were sealed with duct mask or 

temporarily blocked with foam, and the supply plenum was capped just above the ASHP’s 

indoor coil. Using a fan, a compressor, and a spray nozzle, the sealant was released into the ducts 

as an aerosolized spray. Technicians monitored the air leakage through the ducts, and when the 

leakage bottomed out, the equipment was relocated to the return ducts to perform sealing on that 

side as well. The system works best when addressing small holes, but does have its limitations, 

as in the case of large holes or disconnected ducts. Even with the aerosolized sealant doing the 

work, sealing of each individual duct system took several hours for a two-man crew to complete. 

Due to the complex layout of the home, a significant portion of this time was spent locating

obscure supply registers. On retrofit applications, an infrared camera can save hours of work by 

quickly identifying hard to find registers. 

2.3.2.1 Short-Term Test Results

After sealing, the west side ducts showed a total leakage reduction of 201 CFM @ 25 Pa, 

representing a 38% reduction in leakage. During the pre-retrofit testing, the east side ducts were 

too leaky to successfully pressurize with the duct blaster, so a leakage-to-outside test was 

performed instead. The pre- and post-retrofit tests of leakage to the outside for the east side ducts 

showed a leakage reduction of 323 CFM @ 25 Pa, a 62% reduction in leakage. These measures

were considered successful (Table 3). 
10

Table 3. Duct Leakage Test Results

Duct System Location Pre-Retrofit Leakage 

(CFM@25 Pa)

Post-Retrofit Leakage 

(CFM@25 Pa)

Leakage 

Reduction

(CFM@25 Pa)

East, Total Leakage Unable to quantify due 

to instrument limitations 521 ?

East, Leakage to 

Outside 543 220 323

West, Total Leakage 534 333 201

2.3.3 Appliance and Plug Loads Energy End Use and Savings

The retrofit featured the replacement of several major appliances that were nearing the end of 

their useful lives, including two clothes washers, two clothes dryers, a dishwasher, a refrigerator, 

and a freezer. Because these appliances were old, the building owner, Sasha Bruce Youthwork, 

stipulated that these appliances be replaced. While the building owner elected to replace the old 

clothes dryers, they were not recommended as part of the energy retrofit and were excluded from 

the energy savings analysis due to low expectations for energy savings. Additionally, several 

plug loads were not targeted for replacement but were monitored for post-retrofit energy use to 

determine their impact on overall building energy consumption (i.e., three offices and one 

entertainment center).

Primary Research Question: What is the post-retrofit energy use of various end use loads in this 

group home?

For those appliances targeted for replacement as part of the energy retrofit (i.e., one refrigerator, 

one freezer, two clothes washers, and a dishwasher), modeled annual energy use was estimated 

using various sources, including Energy Guide labels and ENERGY STAR calculators. From 

these sources, total energy savings from replacement of these appliances were projected at 898

kWh. (See Table 4.)
11

Table 4. Annual Appliance and Plug Load Energy Consumption, Modeled Versus In-Situ

Appliance

Annual Energy Profile 

From Models

Annualized Energy Profile 

From In-Situ Data

Old 

Appliance 

Energy 

Use 

(kWh)

New 

Appliance 

Energy 

Use 

(kWh)

Modeled 

Savings 

(kWh)

Old 

Appliance 

Energy 

Used

(kWh)

New 

Appliance 

Energy 

Usee

(kWh)

In-Situ 

Savings 

(kWh)

Refrigerator 527a 415a 112 753 667 86

Freezer, First 

Floor 621a 559 a 62 880 546 334

Clothes 

Washer 1 438c 200c 238 174 87f 87

Clothes 

Washer 2 438c 200c 238 Data logger 

failure 87f Unknown

Dishwasher 892a 644a 248 No 

Monitoring

No 

Monitoring

No 

Monitoring

Clothes Dryer 

1 and 2 1951 1951 0 No 

Monitoring 1956 No Monitoring

Entertainment 

Center

Not 

Modeled N/A 0 346 N/A 0

Offices (3 

total)

Not 

Modeled N/A 0 478 N/A 0

Table 4 Notes: a). Energy Guide label, with energy use doubled to assume 8 loads per week instead of 4; b). 

ENERGY STAR Refrigerator Retirement Calculator; c). Energy Guide label for new clothes washer. For old clothes 

washer, assumed EF of 1.18, based on minimum allowable by federal standards in effect at the time of manufacture; 

d). Annualized data are based on short term energy monitoring that occurred over a period of 20 days for all 

appliances but Clothes Washer 1, which spanned a 10 day period. Data are projected forward to 8760 hours to 

estimate totals for a full year of operation; e). Annualized data are based on long term energy monitoring over 8064 

hours that are projected forward to 8,760 hours to estimate totals for a full year of operation; f). One data logger was 

used to monitor the energy use of the two new clothes washers. Total clothes washer energy use is divided evenly 

between the two washers.

2.3.3.1 Short- and Long-Term Test Results

Prior to the replacement of appliances, Kill-A-Watt meters were installed on the refrigerator, 

freezer, and both clothes washers, and monitored for a period of 10–20 days; a longer period was 

desired, but not possible. These in-situ data were then used to project their pre-retrofit energy 

consumption over a typical year. Of these meters, one washing machine’s meter failed during 

this period, so no data were available. Due to budget and scheduling restrictions, no energy 

monitoring equipment was installed on the pre-retrofit clothes dryers, dishwasher, office 

equipment, or entertainment center; no energy monitoring equipment was installed on the postretrofit dishwasher either. Using the short-term in-situ monitoring results of the three reporting 

meters to estimate the energy consumption of the associated appliances over the entire year, the 

result was 14% higher than what was modeled. As a whole, the difference was deemed 

reasonable given the difficulty in estimating frequency of use. Taken individually, however, 

there were some large discrepancies between the modeled energy use estimates and the shortterm measured results when projected over the course of a year, for instance, the freezer and the 

clothes washer. Further detail is provided below and grouped according to end use category. A 
12

summary of the results below can be found in Table 4 and Table 5. Note that Table 4 contains 

annualized values while Table 5 reports on data collected on 11 months of post-retrofit 

monitoring. Therefore, the values in Table 4 and Table 5 do not match for this reason.

Table 5. 11-Month Monitoring Period Appliance and 

Plug Load Post-Retrofit Energy Consumption

End Use Category Average Daily 

Energy Use (kWh)

Total Energy Use 

During 11-Month 

Period (kWh)

Energy Use as 

Percent of WholeBuilding Energy

Food Storagea 5.3 1775 5%

Laundryb 5.8 1960 5%

Entertainment Centerc 1.0 319 1%

Offices (3 total)d 1.3 440 1%

Table 5 Notes: a). Includes two freezers (one old, one new) and one new refrigerator; b). Includes two new clothes 

washers and dryers; c). Includes a DVD player, TV, and cable box; d). Includes a printer, 4 desktop computers and 

monitors, two sets of speakers, two lamps, a radio, a router, and a paper shredder.

2.3.3.1.1 Food Storage

The modeled pre-retrofit annual energy use for the refrigerator and freezer (527 kWh and 621 

kWh, respectively) was lower than the annual energy use projections developed from the shortterm monitoring (753 kWh and 880 kWh), by about 30%. (See Table 4.) Similarly, the modeled 

annual post-retrofit energy use for the refrigerator (415 kWh) was much lower than the postretrofit annualized energy use based on in-situ monitoring (667 kWh). The modeled annual postretrofit energy use for the freezer (559 kWh) was slightly larger than the post-retrofit annual 

energy use based on in-situ data (546 kWh). With results that included both overestimation and 

underestimation of actual energy use, there is no clear explanation for the discrepancy between 

modeled and actual energy use. 

Over the 11 months of post-retrofit data monitoring that occurred, the energy use for food 

storage (one new refrigerator, one new freezer, and one old refrigerator) was 1,775 kWh, which 

represented 5% of total building energy consumption. (See Table 5.)

2.3.3.1.2 Laundry

The ENERGY STAR clothes washer calculator was used to estimate the pre- and post-retrofit 

annual energy use of the clothes washers. This calculator estimates energy use by combining the 

effects of machine energy, water heating energy, and clothes drying energy required for 

additional moisture removal, without disaggregating the individual effects. Using this calculator, 

the pre-retrofit estimated combined energy use was 438 kWh for each of two washers. Based on 

in-situ monitoring over a 10-day period, the imputed annual machine energy use was 174 kWh 

for each of two washers. (See Table 4.) In-situ energy use for coincidental water heating and 

additional clothes drying was deemed too expensive to collect. 

Using the same ENERGY STAR clothes washer calculator, the modeled post-retrofit combined 

annual energy use (machine, water heating, and additional clothes drying energy) was 200 kWh 

for each of two washers. Based on in-situ monitoring, the post-retrofit annual machine energy 

use was calculated as 87 kWh for each of two washers. Any coincidental water heating and 

clothes drying energy savings from the specification of new clothes washers could not be 
13

verified due to limitations of the data logging equipment; however, if these savings were 

realized, they were accounted for within the whole-house energy savings. (See Section 3.2 for 

more information.)

The post-retrofit clothes drying energy use (1,951 kWh) was as modeled (1,956 kWh), based on

the assumption of 16 loads/week, suggesting that the assumption of 16 loads/week was 

reasonable. Based on the energy data collected for clothes washing and drying, it seems 

reasonable to estimate one to two loads per week per group home resident. Over the 11 months

of post-retrofit data monitoring that occurred, the total post-retrofit energy use for laundry 

(machine energy use and electric resistance heating for clothes drying and washing) was 1,960 

kWh, which represented 5% of total building energy consumption. (See Table 5.)

2.3.3.1.3 Entertainment Center

The entertainment center consisted of a TV, cable box, and DVD player. It was not targeted as 

part of the energy efficiency retrofit, so no modeling of the energy use was performed prior to 

the retrofit. Post-retrofit, a Kill-A-Watt meter was installed to estimate the total energy use over 

the full period monitoring period. Based on 1,593 hours of data collected, the projected energy 

use over the 11 months of post-retrofit site-monitoring was 319 kWh, accounting for 1% of the 

total building energy consumption. (See Table 5.)

2.3.3.1.4 Office Plug Loads

Similar to the entertainment center, office plug loads were not targeted as part of the energy 

efficiency retrofit. However, the energy use of the offices was of interest. Office plug loads that 

were monitored included a printer, four desktop computers and monitors, two sets of speakers, 

two lamps, a radio, a router, and a paper shredder. Based on 3,432 hours of data collected from 

four Kill-A-Watt Power Strips installed in three offices, the projected energy use over the 11 

months of post-retrofit site-monitoring was 440 kWh, accounting for 1% of the total building 

energy consumption. (See Table 5.)

2.3.4 Air Source Heat Pump Energy End Use

Replacement of the existing ASHPs was prioritized based on 

building energy simulations that showed great opportunity for 

energy savings. See Section 3.1 for more detailed information 

on the simulations.)

Research Question: What is the post-retrofit energy use of 

various end use loads (e.g., ASHPs) in this group home?

2.3.4.1 Short- and Long-Term Test Results

Due to the aggressive schedule for the retrofit, short-term insitu data on the energy consumption of the compressor and 

fan for both ASHPs was available for only 21 days prior to 

the scheduled retrofit. During this period, which occurred 

from September 23 to October 14, weather conditions were 

mixed and very mild, resulting in a total of just 40 heating 

degree days (HDDs, Base 65) and 495 cooling degree hours 

Risk Mitigation Opportunity

When removing the west ASHP 

during the retrofit, the mechanical 

contractor discovered that the 

existing condensate line was 

plumbed into the sewage disposal 

line, a practice that is against code 

and could result in sewage effluent 

backing into the return plenum. The 

line had clogged—whether due to 

sewage or other blockage was not 

determined—and resulted in more 

than 4 in. of stagnant water that was 

sitting in the return plenum. This 

situation was corrected when the 

new unit was installed, resulting in a 

great improvement in expected IAQ! 
14

(CDHs, Base 74). Without a strong demand for heating or cooling, it was not possible to develop 

a meaningful correlation between space conditioning energy use and outdoor temperatures. 

While short term, pre-retrofit data were inconclusive, 11 months of long-term, post-retrofit data 

on the energy consumption of both ASHPs provided conclusive findings. Combined space 

heating and cooling energy use (i.e., blower, compressor, and resistance heating) for the two 

ASHPs came to 9,570 kWh, accounting for 23% of the total building energy use. This compared 

well with the building energy simulations performed with REM/Rate v12.95 over a typical year, 

which estimated that combined space heating and cooling energy use would account for 28% of 

total building energy use. 

However, once heating and cooling energy use were separated and normalized for weather, the 

in-situ data and modeling data were not as closely aligned. Based on the building energy 

simulation, 25% of post-retrofit total building energy use was expected to be used for heating

(16,881 kWh over 4,459 HDDs, or 3.6 kWh/HDD), with just 3% required for cooling (2,031 

kWh over 10,034 CDHs, or 0.20 kWh/CDH). According to the in-situ post-retrofit data, 

however, just 10% of the total building energy use over the 11 months of monitoring (4,014 kWh 

over 2,651 HDDs, or 1.5 kWh/HDD) was required for heating, while 14% (5,556 kWh over 

19,080 CDHs, or 0.29 kWh/CDH) was required for cooling. In other words, normalized postretrofit heating energy use was 58% less than expected, and normalized post-retrofit cooling 

energy use was 45% more than expected. (See Table 6 for a summary.)

Table 6. Post-Retrofit Normalized ASHP Energy Use, Heating, and Cooling

End Use Category

Modeled, 

Normalized Energy 

Use

In-Situ Normalized 

Energy Use

Percent Increase for 

In-Situ Versus 

Modeled

Space Heating 3.6 kWh/HDD 1.5 kWh/HDD –58%

Space Cooling 0.20 kWh/CDH 0.29 kWh/CDH 45%

The most probable explanation for the increase in normalized cooling energy use and decreased 

heating energy use versus the modeled prediction is the larger-than-expected internal load from 

excessive kitchen operation (and the model’s inability to account for this). Software tools that are 

equipped to handle typical single- and multifamily buildings are not equipped to handle group 

home kitchens where cooking can occur over several hours each day. In the Sasha Bruce home, 

staff typically cooked two to three meals each day for five to 13 people. This resulted in very 

large internal heat gains, as shown by Figure 5, which profiles average kitchen dry-bulb 

temperatures versus average hallway dry-bulb temperatures during the month of February. The 

data showed consistently elevated temperatures in the well-used kitchen, which was typically 

locked when not in use, resulting in elevated temperatures even at night. The lesson learned here 

is that cooking frequency can have a major impact on heating and cooling energy use in group 

homes, and projected savings should be adjusted accordingly. 
15

Figure 5. Kitchen and hallway average dry-bulb temperature profile during the month of February

2.3.5 Indoor Temperatures

Pre-retrofit temperature and relative humidity data were collected near the first-floor thermostats 

and within the west and east basements. Because the weather conditions during the pre-retrofit 

monitoring period were mixed and mild, it was not possible to draw any conclusions (e.g., 

energy use as a function of indoor and outdoor temperature difference, typical set points under 

cooling and heating) from the short-term monitoring of indoor temperatures. However, there was 

sufficient information collected from short-term tests and onsite observations to address the 

following research question related to indoor conditions.

Ancillary Research Question: Can thermostat setbacks be employed to save more energy?

Regarding the opportunity for employing setbacks for the home’s thermostats, transitioning from 

a mechanical thermostat to a digital, programmable thermostat proved difficult for the building 

staff. On multiple post-retrofit site visits, Newport staff noted that “emergency heat” was 

selected as the heating mode, meaning the ASHP was running in electric resistance mode, and 

consuming far more electricity than necessary to heat the home. Initially, maintaining a 

consistent set point also proved difficult for the staff, and thermostat setbacks were deemed 

unacceptable based on concerns for maintaining comfort for staff working the night shift at the 

group home. To address these challenges, the staff was provided a thermostat “cheat sheet,”

which helped to provide an easy reference for maintaining comfort and equipment efficiency, 

while stressing the importance of closing windows during system operation.

70

72

74

76

78

80

82

84

0 2 4 6 8 10 12 14 16 18 20 22 24

Average Indoor Drybulb Temperature (dF)

Hour of Day

Kitchen Hallway
21 

Figure 6. Thermostat “cheat sheet” provided for the building staff 

Perhaps a better solution than cheat sheets and re-education is automation and centralization of 

controls. Internet programmable thermostats are now available that cost less than $300, can lock 

out the maximum heating setting and minimum cooling setting, and can ensure that there are no 

options for “emergency heat” settings. With such a thermostat, the building owner could exercise 

reasonable control over the heating and cooling settings remotely, with little expected sacrifice in 

occupant comfort. 

2.3.6 Domestic Hot Water Consumption 

At the time of the retrofit, the home had two electric resistance tank water heaters, one 15-yearold 80-gal model, and one 3-year-old 50-gal model. Each tank served one shower. An inspection 

of the 80-gal model revealed that this unit was plumbed incorrectly, with the cold water inlet 

piped to the hot water outlet of the tank, and restricting the volume of hot water that could be 

supplied to the home. There were no complaints from the building owners regarding the hot 

water supply from the 50-gal or 80-gal tank, so the design team elected to replace the 80-gal with 

a 50-gal and replumb the unit correctly, which would have the dual benefit of reducing standby 

energy losses and supplying more hot water on demand. A heat pump water heater was 

considered for this application, but was ultimately bypassed due to space constraints in the 

mechanical room. 

Ancillary Research Questions: What is the typical pre- and post-retrofit hot water consumption? 

What are the expected energy savings associated with replacement of the large, old water heater 

with a new, smaller water heater? 

Primary Research Question: What is the post-retrofit energy use of various end use loads (e.g., 

water heating) in this group home? 

 
17

2.3.6.1 Short- and Long-Term Test Results

Pre-retrofit hot water consumption was estimated through short-term monitoring over an 8-day 

period, from September 22 to September 30, for both the west and east side water heaters. A 

longer monitoring period was preferred, but was not feasible based on tight scheduling.

Monitoring was accomplished with a DLJ-SJ75C single-jet water meter that provided 1 pulse per 

gallon. On an hourly basis, total pulses were recorded by an Onset UX120-017M data logger. 

During the 8-day period, the building occupants (approximately eight overnight residents and up 

to five office staff) used an average of 191 gal/day of domestic hot water (DHW). (See Table 7.)

Table 7. DHW Gallons and Energy Use

Pre-Retrofit, 

8-Day Monitoring 

Period

Post-Retrofit, 11-Month Monitoring Period

Average Daily 

DHW Use 

(gal/day)

Modeled 

Average Daily 

DHW Use 

(gal/day)

In-Situ 

Average 

Daily DHW 

Use 

(gal/day)

In-Situ Maximum 

Average Daily 

DHW Use of Any 

Consecutive 8-

Day Period 

(gal/day)

In-Situ 

Normalized 

Energy Use 

(kWh/gal)

In-Situ 

DHW 

Energy 

Use as % 

of Total 

Building

191 90 104 190 0.2 18%

Reductions in hot water use were expected in the post-retrofit home based on the retrofit of two 

clothes washers, a dishwasher, low-flow shower heads, and a faucet aerator with improved water 

use efficiency. Eleven months of long-term post-retrofit data showed a much smaller average 

daily consumption (104 gal/day over the full period), but the same long-term data taken in blocks 

of consecutive 8-day periods contained one 8-day period where the average DHW consumption 

was 190 gal/day. 

A histogram of the post-retrofit 8-day periods showed that the frequency of measuring an 

average daily DHW consumption of 190 gal/day across any 8-day period was less than 1%.

Assuming the average daily consumption over the 8-day periods was normally distributed, the 

likelihood of any 8-day sample underestimating or overestimating the mean by two standard 

deviations is ~5%. For the post-retrofit dataset, this meant that there was a 95% confidence level 

that any 8-day period of monitoring would fall between 55 and 153 gal/day (i.e., within ± 47% of 

the mean of 104 gal/day). If the monitoring periods were extended to 30-day segments within the 

11 months of long-term data, then there would be a 95% confidence that any 30-day monitoring 

period would fall within ± 36% of the mean. In other words, extending the short-term monitoring 

period from 8 days to 30 days would likely result in a closer approximation of the true mean, but 

the difference is not huge; so, collecting water heating and use data over as short of a period of 8 

days does have some merit. Based on these considerations, it is likely that the post-retrofit hot 

water gallons used were significantly reduced, though the magnitude of the reduction cannot be 

conclusively determined due to the limited period of the pre-retrofit dataset.

Building energy simulations were performed to estimate the energy savings associated with 

replacement of the 15-year-old, 80-gal electric resistance water heater with a 50-gal electric 

resistance water heater. Using REM/Rate v12.95, the estimated savings were 506 kWh (7% 
18

savings) with an average consumption of 90 DHW gal/day, representing a normalized postretrofit energy use of 0.2 kWh/gal. A detailed explanation of the building energy simulations and 

assumptions can be found in Section 3 of this report.

Based on in-situ data, the model slightly underestimated the post-retrofit average gal/day (102 

gal/day, actual). However, the model of post-retrofit normalized energy use of 0.2 kWh/gal, was 

right on the mark, as confirmed through in-situ data. Over the 11 months of post-retrofit data 

monitoring that occurred, the energy use for water heating was 7,143 kWh, which represented 

18% of total building energy consumption over the period. (See Table 7.)

2.3.7 Ventilation

To mitigate any negative effects that the retrofit’s air sealing measures could have on IAQ, 

ASHRAE 62.2-2010 was referenced to determine the recommended ventilation rates for the 

building. Normative Appendix A of this standard is provided for the specific application of 

calculating local exhaust and whole-house mechanical ventilation requirements for existing 

buildings. Using Appendix A, the designer has more flexibility to credit the infiltration rate of 

the building as well as the ventilation rate of local exhaust toward the required whole-house 

ventilation rate, Qfan. Further, the designer also has the option to increase Qfan to offset any 

local exhaust rates in kitchens and bathrooms that would otherwise be required.

Ancillary Research Question: Using Appendix A of ASHRAE 62.2, what are the recommended

local exhaust flow rates and whole house ventilation rates for acceptable IAQ?

2.3.7.1 Short-Term Test Results

Across two bathrooms and one kitchen, there was only one exhaust fan installed in the preretrofit home. Using the Energy Conservatory’s Exhaust Fan Flow Meter, the measured flow rate 

of the east bathroom fan was 54 cfm. (See Table 8.) The post-retrofit building infiltration rate 

was 11,781 cfm at 50 Pascals, as described previously in Section 2.3.1. Using these inputs, and 

following the methodology in ASHRAE 62.2-2010, no additional ventilation requirements were 

identified beyond what was provided in the pre-retrofit case; see the calculation worksheet in 

Appendix A of this report. 

Table 8. Ventilation Location and Flow Rates

Ventilation 

Location

Pre-Retrofit 

Flow Rate 

(CFM)

Diagnostic Equipment

East Bath 54 Energy Conservatory’s Exhaust Fan Flow 

Meter, Accuracy ± 10%

West Bath No fan N/A

Kitchen Recirc only N/A

Whole House No fan N/A

When following the methodology of ASHRAE 62.2-2010 Appendix A, it is important to 

remember that the standard is meant to identify the minimum airflows that are recommended for 

maintaining acceptable IAQ. No doubt the IAQ of this group home could have been improved 

by increasing ventilation and filtration. In fact, the preference of the design team was for 
19

installation of humidity-controlled local exhaust in the kitchen and bathrooms. However, this 

measure was ultimately not pursued due to budget constraints and lack of any recommended 

changes to ventilation rates using ASHRAE 62.2-2010. One of the lessons learned from this 

project was that to achieve IAQ objectives, buy-in from the project sponsor should be pursued as 

early in the process as possible.

2.3.8 Window Operation

Historically, inefficient occupant window operation has posed a challenge to temperature control 

and efficient operation of space conditioning equipment. When building occupants are not 

responsible for utility bills (the case for this and other group homes), there is often little 

motivation for the occupants to consider the energy impact of window operation. 

Primary Research Question: What is the estimated impact of window openings on the equivalent 

leakage area (ELA) of the building?

2.3.8.1 Long-Term Test Results

During the energy retrofit, window state sensors were installed at each 

window and one door of the home, a total of 33 sensors in all. These

on/off remote state sensors recorded the time interval that a window was

open and closed. Window state sensors measured 1.8 × 2.4 × 0.8 in. and 

were easily installed on the surface of a vinyl window frame. Because 

state sensors measure only on/off events, they were not capable of 

indicating the actual opening dimension (i.e., the opening height would 

be an analog measurement, not an on/off digital measurement), but 

they were useful in recording the time during which the window was 

known to be open a minimum distance. These particular state 

sensors tripped when a window was opened a minimum of 1.5 in. 

To estimate the minimum impact of window openings on the building leakage, the following 

steps were taken (a detailed explanation of these calculations may be found in Appendix B).

• The building’s baseline ELA was calculated using results from a multipoint 

depressurization test with windows closed.

• The minimum opening area for each monitored window and door was calculated using 

measurements taken on-site, and assuming that the minimum opening distance was 1.5

in., based on the minimum distance required to trigger an “open” event.

• Flow through the opening was calculated at a pressure difference of 4 Pa, assuming the 

window opening can be characterized as a sharp-edged orifice.

• For each hour during the monitoring period, the ELA of each window was calculated 

based on the flow through the opening at 4 Pa, and the fraction of the hour that the 

window was open. 

• The minimum “dynamic ELA” (i.e., the real-time minimum ELA of the building 

calculated based on window openings) was determined at each hour of the monitoring 

period by summing the baseline ELA with the ELA of each open window. 

Figure 7. Window state sensor
20

Once the minimum dynamic ELA was calculated on an hourly basis (8,064 hours total during the 

period of monitoring), the data were filtered to qualify the interaction of window operation and 

ASHP energy use; all hours where no ASHP cycles were recorded were dismissed, leaving 6,273 

hours of data. The dynamic ELA percent increase was calculated versus the building’s baseline 

ELA on an hourly basis. Data were then grouped into bins based on the hourly outdoor 

temperature minus the indoor dry-bulb temperature, resulting in Figure 8.

From Figure 8, it is obvious that dynamic ELA and use of the ASHP are not well coordinated. 

Generally speaking, in a building operated for maximum efficiency, ASHP energy use and 

window openings would not overlap. The operators of this building, however, had windows open 

each hour of the 11 months monitored, regardless of whether the ASHP was operating. 

Occupants also tended to open more windows as outdoor temperatures became colder, increasing 

the minimum dynamic ELA by more than 19% when temperature differentials across the 

envelope were the largest. Interestingly, window openings fell off as outdoor temperatures 

increased, suggesting that occupants were less tolerant to the introduction of warmer outdoor air 

than colder outdoor air. Overall, the data point to opportunities for energy savings through better 

management of window operation by the occupants, especially during periods of colder outdoor 

temperatures.

Building occupants were not surveyed as to reasons for window operation. However, staff did 

communicate that the basement was typically cold in the winter, regardless of how high they set 

the first-floor thermostat. Cold basements in old buildings are not unusual, and could be a factor 

of poor insulation, stack effect, undersized ducts, etc. However, the large internal heat gains 

produced by extensive cooking without exhaust ventilation could be partially to blame for 

temperature variation across floors that could lead to overheating of the first and second floors 

and ultimately, occupant operation of windows. For this reason (and for reasons of IAQ), 

installation and operation of kitchen exhaust ventilation merit consideration. Without further 

study, it is unclear whether venting the kitchen would reduce or increase heating season energy 

use.
21

Figure 8. Effect of window operation (during hours with ASHP cycles) on building ELA at various 

outdoor to indoor temperature differentials

0

2

4

6

8

10

0%

4%

8%

12%

16%

20%

-55 -45 -35 -25 -15 -5 5 15 25

ASHP Average Houlry Energy Use 

(kWh)

Minimimum % Increase in ELA

Temperature Differential (Outdoor minus Indoor)

ASHP Energy Min Dynamic ELA
22

3 Analysis

This section contains information on the methods and results of building energy simulations, a 

summary of post-retrofit energy end use and savings, and an economic analysis. 

3.1 Building Energy Simulations

Building energy simulations were used to estimate expected savings. While the latest version of 

BEopt (v1.2 at the time the simulations were conducted) was the preferred simulation tool for 

this effort, use of the tool proved difficult due to its inability to model the following site-specific 

parameters:

• Exterior wall orientations of multiple wall types (e.g., a common wall and exterior wall 

sharing the same orientation)

• Number of bedrooms exceeding maximum permitted by BEopt

• Finished basement wall height of less than 8 feet

• Multiple ceiling sections with different insulation configurations (e.g., blown-in cellulose 

in vented attic and fiberglass batts in vaulted ceiling)

• Multiple ASHPs of different efficiencies and equipment ages

• Multiple water heaters of different sizes and EFs.

Based on these limitations, and prior to the retrofit, an initial round of simulations was conducted 

using REM/Rate v12.95. Where possible, building and mechanical characteristics were verified 

through short-term testing and onsite inspection. Where site inspections or measurements were 

not possible, critical assumptions were made regarding expected performance or characteristics. 

For example, lacking a low-cost, reliable protocol for field verification of ASHP performance, 

performance parameters were estimated based on Building America House Simulation Protocols, 

as a function of assumed maintenance schedules and equipment age (Hendron and Engebrecht 

2010). (See Table 9.)

Table 9. Pre-Retrofit Mechanical Equipment Performance Assumptions

Equipment Assumed Performance Age (years) Maintenance

ASHP, West 11.9 SEER; 7.0 HSPF 3 Seldom

ASHP, East 5.6 SEER; 4.0 HSPF 19 Seldom

DHW, West 80 gallon, 0.80 EF 15 Seldom

DHW, East 50 gallon, 0.89 EF 3 Seldom

Other assumptions were made for the pre-retrofit condition of the building envelope as well as 

the expected impact of retrofit measures. For example, because the home was built in 1900, and 

because there was no attic access, it was assumed that there was no attic insulation. However, 

when an attic hatch was created for access during the retrofit, the attic was found to have R-19 

fiberglass batt insulation. Similarly, it was assumed that retrofit air sealing efforts would result in 

a 20% improvement in the building leakage, which was thought to be conservative based on 

weatherization program reports that are typically in the range of 30% (Blasnik 2007). However, 
23

the post-retrofit measured improvement was a 7% reduction in leakage. (See Section 2 for more 

information.)

These findings warranted a revision to the building energy simulation heating and cooling energy 

use estimates. Initial and revised expected energy savings are shown in Table 10. The data show 

an initial expected site and source energy savings of 44%, and a revised expected site and source 

energy savings of 22%. The majority of this gap between the initial projections and revised 

projections was due to under estimating the R-value of the ceiling insulation, though it was also 

impacted by correcting for the overestimation of the air sealing benefit. 

Table 10. Building Envelope Modeling Assumptions

Assumed Performance

Parameter Initial Simulation Set Revised Simulation Set

Ceiling Insulation R-0 R-30 R-19 R-49

Air Sealing (ACH 50) 22.2 17.7 22.2 20.6

Interestingly, both the initial and revised simulations of the pre-retrofit home fell short of 

predicting the total energy consumed by the home, as determined by pre-retrofit utility bill data. 

The difference between actual (based on utility bill data) and expected annual site energy 

consumption was found by subtracting modeled heating, cooling, DHW, lighting, and targeted 

appliance energy use from the utility bill use, and is listed as “Other, Unaccounted” in Table 11. 

The initial simulation’s projections were 20% short of the actual total site energy consumed, 

which seemed acceptable due to high variability in occupants, high cooking loads, and the 

existence of three fully staffed offices within the building. However, the revised simulation was

~40% short of the total – pointing toward some gaps between the modeled home and its 

operation (e.g., window operation, likely higher cooking loads, three offices, etc.). The data 

acquisition system, which included individual energy monitoring for the refrigerator, freezers, 

washing machines, clothes dryers, water heaters, and ASHPs and post-retrofit utility bill 

collection were helpful in clarifying the actual, post-retrofit savings.

Table 11. Estimated Annual Site Energy, Initial and Revised Simulations

End Use

Estimated Annual Site Energy 

(kWh)

Initial Simulation Revised Simulation

PreRetrofitPostRetrofit Savings Percent 

Savings

PreRetrofitPostRetrofit Savings Percent 

Savings

Heating 44,285 16,881 27,404 62% 28,457 16,026 12,431 44%

Cooling 8,015 2,310 5,705 71% 5,361 2,031 3,330 62%

DHW 7,233 5,795 1,438 20% 7,233 6,727 506 7%

Lighting 2,218 1,277 941 42% 2,218 1,277 941 42%

Targeted 

Appliances 2,916 2,018 898 31% 2,916 2,018 898 31%

Other, 

Unaccounted 18,377 18,377 0 0% 36,859 36,859 0 0%

Total 83,044 46,658 36,386 44% 83,044 64,938 18,106 22%
24

3.2 Building Energy Use—Utility Bills and End Use Disaggregation

Pre-retrofit and post-retrofit performance data are the ultimate basis for quantifying energy 

savings. When overlaid with in-situ data on energy end use (collected via discrete data loggers) 

and normalized for outdoor temperature, a good approximation of the energy and dollar savings 

can be made. 

Primary Research Questions: What is the estimated annual energy savings from the retrofit 

based on data collected over the monitoring period? What percent of the total building energy 

use is accounted for by the energy end use categories that were monitored?

3.2.1 Post-Retrofit Energy Savings

By examining a graph of 19 months of pre-retrofit utility bills versus outdoor temperature, it was 

obvious that outdoor temperature was a large driver in the monthly whole-building energy 

consumption. A second-order polynomial regression of these data yielded an acceptable curve 

fit, with an R2 of 0.84. A similar exercise on 11 months of post-retrofit data yielded an even 

closer fit, with an R2 of 0.92. Based on this close correlation, the post-retrofit monitoring period 

was curtailed at 11 months, which was deemed to be a sufficient length of time to accurately 

characterize post-retrofit performance. The one missing month was November, which had low 

space conditioning loads and an outdoor average temperature that fell within the range of 

temperatures recorded for other months. 

By applying the polynomial regressions from the pre- and post-retrofit data to 30-year climate 

normal monthly average temperatures, annual energy use under pre- and post- conditions were 

estimated for a typical year. This method resulted in an estimated 41% savings for the postretrofit home, or roughly 33,867 kWh of energy savings valued at $4,403 in the first year of 

operation (based on a utility rate of $0.13/kWh).

3.2.2 Post-Retrofit Energy End Uses

Energy end use as a percent of total building energy use was computed by comparing end use 

logged data with whole building energy use as reported on utility bills. Hourly, in-situ energy use 

data on clothes drying, water heating, space heating and cooling was collected through 

monitoring over an 11-month period. In-situ energy use data on clothes washing, food storage 

(refrigerator and freezers), office plug loads, and an entertainment center were collected for 

discrete periods during this time, averaged on a daily basis, and projected onto monthly billing

periods based on the number of days in the month. 

Total building energy use was derived from utility bills, after subtracting the energy use of a 

dehumidifier. A stand-alone dehumidifier was installed post-retrofit to address pre-retrofit 

moisture conditions in the basement, and so was excluded from the post-retrofit analysis. 

Monthly energy end uses were then subtracted from the total building energy use across the same 

period to quantify the energy end use for lighting, cooking, and other miscellaneous plug loads. 

The largest metered end use over the 11 months of monitoring belonged to the ASHPs at 24% 

(with roughly 10% for heating and 14% for cooling), followed by the water heaters at 18%. 

Laundry and food storage each accounted for 5%, and three offices and the entertainment center 

each accounted for 1%. Unmonitored loads such as lighting, cooking, and other miscellaneous 

loads accounted for 46%.
25

Figure 9. Total energy use (pre- and post-retrofit) and disaggregated energy use 

(post-retrofit only) as a function of outdoor dry-bulb temperature

3.3 Cost Effectiveness

While cost effectiveness of energy retrofits relative to energy savings can be measured by many 

methods, the metric typically used for multifamily retrofits is the SIR. Stated simply, the SIR 

evaluates the present value of total expected savings over a time horizon, divided by the 

investment cost of the measures. Within typical industry guidelines, and for the purposes of this 

project, a SIR of ≥ 1.0 was considered to be cost effective.

Primary Research Question: What SIR can be expected for an EER with a 30% energy savings 

target?

For this exercise, the following assumptions were made in calculating the SIR:

• 10-year time horizon

• Discount rate of 2% (based on survey of currently available, 5-year CD rates)

• Retail pricing for installed cost of measures (incentives and other discounts were 

ignored). 
26

• Residual value of existing equipment is equal to the cost of a standard efficiency 

replacement at year zero, and decreases linearly over time. When the equipment reaches 

its industry accepted useful life, it is assumed to have a residual value of zero. 

• Useful life derived from an NAHB/Bank of America survey (Seiders et al. 2007), or 

estimated from industry data/experience. 

• Investment cost of retrofit measures taken as installed cost of the high efficiency 

replacement less the installed cost of a standard efficiency replacement, plus the residual 

value of the existing measure

• Year zero electricity price of $0.13/kWh

• Annual electricity price escalation rate of 3%.

The total incremental energy retrofit investment cost was determined to be $22,678. (See Table 

12.) A project’s SIR is highly dependent on the incremental investment cost of the individual 

energy conservation measures (ECMs) (high efficiency replacement cost less low efficiency 

replacement cost plus residual value of existing equipment). So, as much as possible, the team 

focused on recommending replacement of existing equipment with low residual value and 

minimal incremental costs. However, some individual ECMs with high incremental investment 

costs were selected based on their expected energy savings benefit, as determined by modeling 

or calculations (e.g., the ASHP). 

The total incremental investment cost of the retrofit was also significantly impacted by the 

choice to replace some items that still had high residual value, such as an ASHP that was only 3 

years old and appliances that performed fairly well but not as well as new ENERGY STAR 

appliances. The SIR would likely have been even more attractive without specifying some of 

these measures, but the magnitude of energy savings would not have been as high, and the goal 

of the team was to maximize energy savings while maintaining a SIR > 1, not to maximize 

the SIR. 
27

Table 12. Investment Cost of Retrofit Measures

Retrofit Measure Retrofit 

Action Estimated 

Age

Estimated 

Useful 

Life

Estimated 

Installed 

Costs, High 

Efficiency 

Replacement

Estimated 

Installed 

Costs, 

Standard 

Efficiency 

Replacement

Residual 

Value of 

Existing 

Measure at 

Time of 

Retrofit

Retrofit 

Net 

Investment 

Cost

ASHP, West Replace 3 16 $8,790 $6,422 $5,218 $7,585

ASHP, East Replace 19 16 $13,184 $9,634 $1,606 $5,156

DHW, West Replace 15 11 $1,200 $1,800 $0 ($600)

TStat, West Replace The incremental costs of programmable thermostats are not included in the 

analysis because replacement is typical with new HVAC equipment. Also, 

programmable thermostats are required by the 2009 International Energy 

Conservation Code. 

$0

TStat, East Replace $0

Windows Replace 12 20 $8,775 $8,775 $0 $0

Luminaires Replace 1 0.11 $125 $100 $0 $25

Exterior Light 

Fixtures Replace 15 15 $687 $687 $0 $0

Attic Insulation Improve N/A N/A N/A N/A N/A $1,979

Duct Sealing Improve N/A N/A N/A N/A N/A $5,550

Air Sealing Improve N/A N/A N/A N/A N/A $500

Interior Lighting 

Occupancy Sensors Improve N/A N/A N/A N/A N/A $950

Refrigerator Replace 5 13 $949 $949 $584 $584

Freezer Replace 2 11 $579 $579 $474 $474

Clothes Washer 1 Replace 9 10 $999 $999 $100 $100

Clothes Washer 2 Replace 18 10 $999 $999 $0 $0

Dishwasher Replace 6 9 $549 $449 $150 $250

Low-Flow Aerators Replace N/A N/A $125 N/A N/A $125

Total – – – – – $22,678
28

Though the SIR is a measure of the economic performance across a basket of ECMs, further 

detail on some of the individual measures is warranted. The high cost of the ASHP was driven 

both by its high efficiency (equipment costs for 17 SEER versus a standard 13 SEER can be 

about 80% higher) and also by unique challenges of its installation. For example, the east 

outdoor unit was located on the roof and required special equipment to access, which is reflected 

in the pricing, assumed to account for 60% of the total quote for both the east and west units.

While duct sealing can be an effective measure for energy savings, its investment cost was high 

because it was regarded as an elective measure or an improvement, rather than a replacement.

Clothes dryers were not included in the investment cost because they were not expected to 

significantly contribute to energy savings. In several cases, the installed cost of the high 

efficiency replacement was equal to the installed cost of the standard efficiency replacement. 

This generally occurred when the high efficiency replacement was a commoditized product, and 

lower efficiency products were not readily available (e.g., it was difficult to find non-ENERGY 

STAR appliances). In one case, the replacement of an 80-gal water heater with a 50-gal water 

heater, the selected ECM was actually lower cost than the standard efficiency measure.

Based on the initial building energy simulation results, expected annual electricity savings were 

36,386 kWh, valued at $54,659 over 10 years (after applying discount and electricity price 

escalation rates). This resulted in an initial SIR of 2.4 ($54,659/$22,678=2.4). The SIR was 

adjusted to 1.2 after short-term test results were incorporated into a revised building energy 

simulation set, and expected annual electricity savings were adjusted to 18,106 kWh ($27,199

valuation over 10 years). Once long-term energy use data were collected, it was apparent that the 

project saved much more than the revised simulations had projected, at 33,867 kWh over a 

typical year for a SIR of 2.2 ($50,875 valuation over 10 years). The simple payback of the

retrofit was calculated at 5.2 years ($22,678 net investment to provide annual energy savings 

of $4,403).

In practice, decisions are made not on a purely economic basis, but on the basis of other factors 

as well, such as comfort, function, safety, age of equipment, quality, and consumer preferences. 

For example, the pre-retrofit home had nonfunctioning exterior lighting that, in its 

nonfunctioning state, was not consuming any energy. Replacement of the lighting with any type 

of fixture, no matter how efficient, will ultimately result in higher post-retrofit energy 

consumption. Nonetheless, this measure was incorporated within the scope of the retrofit because 

having adequate lighting was considered a safety feature.

It is also important to note that the revised building energy simulations used to project cost 

effectiveness fell short of projecting the total energy consumption on site and the energy savings,

suggesting gaps between the model’s assumptions and actual operation of the group home. For 

more accurate modeling, more flexibility is needed within the inputs of software models to 

adequately characterize the unique characteristics of group homes.
29 

4 Conclusion

Conclusions are grouped according to primary research questions, as listed below. 

What are the estimated annual energy savings from the retrofit based on data collected over the 

monitoring period? 

Post-retrofit annual energy savings versus pre-retrofit conditions were estimated at 44%, well 

above the Building America target of 30% savings. This estimate was built up through a secondorder polynomial regression of pre- and post-retrofit monthly energy use as a function of average 

monthly outdoor dry-bulb temperature. Using 30-year climate normal monthly average dry-bulb 

temperatures, the regressions were then used to approximate the monthly and annual energy use 

for a typical year under both the pre- and post-retrofit scenarios. Energy savings were then 

calculated by subtracting the post-retrofit estimated energy use from the pre-retrofit estimated 

energy use, showing 41% annual savings. The monetized value of the 41% savings was $4,403 

(based on an electric utility rate at $0.13/kWh). (See Section 3.2 for more information.) 

What SIR can be expected for an EER with a 30% energy savings target? 

Based on initial, utility-bill calibrated simulations, this group home was expected to save 44% of 

site and source energy and to achieve a SIR of 2.4. Due to limitations in accomplishing retrofit 

measures (e.g., air sealing limitations due to restricted accessibility) and the mid-retrofit 

discovery of higher than expected ceiling insulation, the initial simulated energy savings estimate 

was revised from 44% to 22% with an associated SIR of 1.2. (See Sections 2.3.1 and 3.1 for 

more detail.) However, based on long-term data collection, a 41% annual energy savings was 

achieved, corresponding to a SIR of 2.2. From these results, a group home EER with a target of 

30% energy savings may expect to achieve a SIR between 1 and 2. 

What is the post-retrofit energy use of various end use loads in this group home (i.e., space 

heating and cooling, water heating, laundry, food storage, offices, entertainment center, etc.); 

and what percent of the total building energy use is accounted for by the energy end use 

categories that were monitored? 

Over the 11-month monitoring period (deemed a sufficient length of time to characterize postretrofit performance based on the goodness of fit of a regression of building energy use as a 

function of outdoor dry-bulb temperature), post-retrofit energy use was tabulated at 24% for 

space heating and cooling (~10% for heating at 4,014 kWh and 14% for cooling at 5,556 kWh), 

18% for DHW (at 71,43 kWh), 5% for laundry (at 1,960 kWh), 5% for food storage (at 17,75 

kWh), 1% for offices (at 440 kWh), and 1% for the entertainment center (at 319 kWh). It is 

important to note that the space heating and cooling percentages are expected to shift with 

variations in weather. The 11 months of monitoring covered a very mild winter, so in typical 

years, space heating could be expected to account for a larger percentage of energy use. 

Taken as the difference between whole-building energy use on utility bills and the energy end 

uses annotated above, lighting, cooking, dishwashing, and other miscellaneous plug loads 

accounted for 46% of the post-retrofit energy use (17,850 kWh). Based on observations while 

onsite and on kitchen dry-bulb temperatures, cooking loads were extremely high. The extensive 
30

cooking had the effect of increasing expected internal gains, reducing heating loads, and 

increasing cooling loads. Most residential building energy simulation packages are not 

adequately equipped to deal with the cooking loads and internal heat gains that are associated 

with group homes. 

How does the occupant operation of windows affect the building airtightness during the 

operation of the ASHP?

Data on window operation showed that dynamic ELA and use of the ASHP were not well 

coordinated, with windows open each hour of the 11 months monitored, regardless of whether 

the ASHP was operating. Occupants also tended to open more windows as outdoor temperatures 

became colder, increasing the minimum dynamic ELA by more than 19% when temperature 

differentials across the envelope were the largest. Conversely, window openings fell off as 

outdoor temperatures increased, suggesting that occupants were less tolerant to the introduction 

of warmer outdoor air than colder outdoor air. Overall, the data point to opportunities for energy 

savings through better management of window operation by the occupants, especially during 

periods of colder outdoor temperatures.

What are the challenges and solutions to making the retrofit package replicable on similar 

building types?

Key characteristics of the pre-retrofit building that lent themselves to the success of this project 

from an energy and economic perspective were: 

• Utility bills indicating high energy use intensity (65 kBtu/ft2 in this case)

• Old, inefficient heating and cooling equipment in need of replacement

• A leaky building envelope with opportunities for air sealing

• Lighting loads that could be reduced through replacement of low-efficacy luminaires and 

installation of occupancy sensors

• Poor ceiling insulation.

Buildings that exhibit similar characteristics are likely to be good candidates for replicating 

energy savings at a very low incremental cost.

Even if the building is a great candidate for an energy retrofit, multiple challenges to achieving 

targeted energy savings goals should be expected, and budgets/schedules should be adjusted 

accordingly. Two of the largest challenges to achieving energy savings targets within this project 

were 1) hidden and inaccessible flues and 2) occupant opening of windows during operation of 

the ASHPs. Several hidden and inaccessible flues were not air sealed during this project because 

their presence was only discovered after a wall and attic were opened during the retrofit and 

because there were insufficient funds at that time to open all the additional walls to address all of 

them. This example illustrated the value of having sufficient flexibility in a retrofit budget and 

schedule to address surprises as they arise. As feasible, retrofit measures that are expected to 

have a high return on investment (e.g., air sealing) should be scheduled earlier in the project to 
31 

ensure that sufficient funds are available for making changes to the scope when surprises do 

occur. 

Inefficient window operation by occupants was identified through data collected with state 

sensors that were installed during the retrofit. Feedback was provided to the building owner and 

staff, but window operation during space heating or cooling continued to be significant. 

Motivation for staff and occupants to save energy remains a challenge, and educating occupants 

in such a high turnover environment can be a large drain on staff. Considering these limitations, 

one option to improve performance of energy retrofit measures that was not explored in this 

project would be to reduce occupant and staff control of energy savings measures. For example, 

replacing the current thermostat (which has a confusing “emergency heat” setting that can seem 

like a good choice for a chilly occupant) with an internet-programmable thermostat that can be 

controlled remotely by the building owner, would ensure that the ASHPs do not operate 

needlessly in resistance heating and could also ensure that heating and cooling thermostat set 

points do not exceed recommended limits. The practice of centralizing thermostat control is 

much more common in commercial buildings, but less so in residential settings, such as this 

group home. 

Another opportunity for reducing operation of the windows during the winter that merits 

consideration is improving indoor climate control through installation and use of kitchen 

ventilation. Daily, prolonged use of cooking appliances without ventilation increases internal 

gains on the first floor, which could result in greater temperature stratification (e.g., cold 

basement and warm upstairs—a complaint logged by the occupants), increased stack effect, 

poorer temperature and air distribution from fewer heat pump cycles, etc. Without further study, 

it is unclear whether venting the kitchen would reduce or increase heating season energy use, but 

it would certainly be expected to improve IAQ, and should be explored further. 

And while these challenges deserve attention in this building and other similar buildings, they by 

no means undermine the feasibility of cost-effective energy retrofits in such projects. Despite 

less than stellar occupant management of energy retrofit measures, significant energy savings 

were still realized. 
32

5 References

ANSI/ASHRAE 136-1993. A Method of Determining Air Change Rates in Detached Dwellings.

ANSI/ASHRAE 62.2-2010. Ventilation and Acceptable Indoor Air Quality in Low-Rise 

Residential Buildings. 

ASHRAE 119-1988. Air Leakage Performance for Detached Single-Family Residential 

Buildings. 

ASHRAE Handbook of Fundamentals. 2009. American Society of Heating, Refrigerating and 

Air Conditioning Engineers Inc., Atlanta.

Blasnik, M. (2007). Energy Conservation: What are my choices? What can I save? Presented at: 

The 21st Annual National Low Income Energy Conference. Nashville, TN. June 5, 2007. 

Available at 

www.nliec.org/2007%20Conference/Presentations/MBlasnik_Energy%20Conservation.pdf. 

Hendron, R.; Engebrecht, C. (2010). Building America House Simulation Protocols. Golden, 

CO: National Renewable Energy Laboratory, NREL Report No. TP-550-49426.

Neuhauser, K.; Bergey, D; and Osser, R. 2012. Leveraging Limited Scope for Maximum Benefit 

in Occupied Renovation of Uninsulated Cold Climate Multifamily Housing. Available at 

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

multifamily.pdf.

Seiders, D. et al (2007). National Association of Home Builders/Bank of America Home Equity 

Study of Life Expectancy of Home Components. 
33

Appendix A. ASHRAE 62.2-2010 Whole-House Mechanical 

Ventilation Calculations

Using Normative Appendix A of ASHRAE 62.2-2010, and accounting for building infiltration, 

geometry, and local exhaust rates, it was shown that no additional mechanical ventilation was 

required for the building. Results from the procedure, which references ASHRAE Standard 136 

and ASHRAE Standard 119 are shown below. 

Sasha Bruce, ASHRAE 62.2-2010 Normative Appendix A; WHMV requirement calculator, including credit for infiltration and 

calculation of local exhaust deficit

Green cells are Inputs Yellow cells are Outputs

Building Characteristics

4392 floor area of space (ft2)

16 occupants, assumed (2 per bedroom, 4 in offices)

9 "bedrooms" (6 dedicated bedrooms on 3rd story, 3 offices on main level)

3 stories

8 avg ceiling height

24 building height

CFM50 ACH50 ELA (in2)

Pre-Retrofit 12716 21.7 700

Post-Retrofit 11781 20.1 648

ASHRAE 119

L, post 4.50 leakage (ft2)

(h/ho)^0.3 1.39

Ln 1.43 normalized leakage

ASHRAE 136

W 0.76 weather factor for Washington, D.C. from ASHRAE 136 table

Ai 1.08 infiltration, ASHRAE 136_4.2 (ACHnat)

634 infiltration (cfm nat)

ASHRAE 62.2-2010, 4.1.3

87.8 default infiltration rate based on sqft, 4.1.3 (cfm)

273 infiltration credit, 4.1.3 (cfm)

Ventilation required

119 Qfan, Equn 4.1a

10 persons assumed by Equn 4.1a

6 additional persons

164 adjusted Qfan, 4.1.1

54 Bath 1 flow, measured on-site (cfm)

0 Bath 2 flow, measured on-site (cfm)

0 Kitchen flow, measured on-site (cfm)
34

20 Bath 1 window credit, A3.2 (cfm)?

20 Bath 2 window credit, A3.2 (cfm)?

20 Kitchen window credit, A3.2 (cfm)?

0 Bath 1 deficit, A3.1 (cfm)

30 Bath 2 deficit, A3.1 (cfm)

80 Kitchen deficit, A3.1 (cfm)

110 Local exhaust deficit (cfm)

27.5 Required additional airflow ASHRAE 62.2-2010 A3.3 (cfm)

0 Qfan, less infiltration credit, includes local exhaust deficit compensation (cfm)
35

Appendix B. Calculation of Minimum Dynamic Equivalent 

Leakage Area

1. Using air flow and pressure differential data pairs from a post-retrofit multipoint building 

pressurization test with all windows closed, calculate the flow exponent, n, and the flow 

coefficient, c, of the building using Equation B1, below:

Q = c(∆p)n [Equation B1]

where

Q = air flow, cfm

c = flow coefficient, cfm/(in. of water)

∆p = pressure differential, in. of water

n = pressure exponent, dimensionless 

Source: ASHRAE Handbook of Fundamentals 2009 16.15, equation 40

2. Calculate the baseline ELA for the post-retrofit building at 4 Pa (0.016 in w.g.) with windows 

closed using Equation B2, below:

AL = c

5.39CD

�ρ

2

∆pr

(n−0.5) [Equation B2] 

where

AL = equivalent leakage area, in2

CD = discharge coefficient, dimensionless (use 1.0)

ρ = density of air, lbm/ft3

∆pr = reference pressure difference (use 0.016 in. of water)

n = pressure exponent, dimensionless 

Source: ASHRAE Handbook of Fundamentals 2009 16.15, equation 44

3. Calculate the cross sectional opening area for each individual window (in2). Based on the 

state sensors used in this project, the minimum height of the opening required to trigger an 

open event was 1.5 in.
36

4. Calculate the air flow through each opening at 4 Pa (0.016 in w.g.), using Equation B3, 

below. 

Q = 776CDA�2∆p/ρ [Equation B3] 

where

Q = air flow rate through open window, cfm

776 = unit conversion factor

CD = discharge coefficient, dimensionless (use 0.6, assuming the window behaves like a flat 

plate orifice)

A = leakage area of opening, in2

∆p = pressure difference across opening (use 0.016 in. of water)

ρ = density of air, lbm/ft3

Reference: ASHRAE Handbook of Fundamentals 2009, 16.13, equation 36. 

5. Using equation B3, calculate the ELA of each window opening (solve for A), assuming a 

discharge coefficient of 1.0 (typical for whole building calculations). All other variables (Q,

∆p, and ρ) retain their values from the previous step.

6. Add the ELA of each window to the baseline ELA of the building to determine the minimum 

dynamic ELA over the period of observation.
37

Appendix C. Floor Plan of Sasha Bruce Group Home
38
39
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