Evaluation of Savings in 

Energy-Efficient Public 

Housing in the Pacific 

Northwest

A. Gordon, M. Lubliner, L. Howard, and R. Kunkle

BA-PIRC

October 2013
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iii

Evaluation of Savings in Energy-Efficient 

Public Housing in the Pacific Northwest

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: 

M. Lubliner, A. Gordon, L. Howard, and R. Kunkle

Washington State University Extension Energy Office

for

Building America Partnership for Improved Residential Construction

1967 Clearlake Road

Cocoa, FL 32922

NREL Technical Monitor: Stacey Rothgeb

Prepared under Subcontract No. KNDJ-0-40339-02

October 2013
iv

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v

Table of Contents

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

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

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

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

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

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

2 Energy Audits ....................................................................................................................................... 3

2.1 Homeowner Surveys........................................................................................................................ 7

3 Modeling Methods ................................................................................................................................ 8

3.1 Energy Analysis ............................................................................................................................... 8

3.2 Economic Analysis........................................................................................................................... 9

4 Billing Analysis Methods ................................................................................................................... 11

5 Results................................................................................................................................................. 12

5.1 Modeling......................................................................................................................................... 12

5.2 Economic Analysis......................................................................................................................... 14

5.3 Billing Analysis of Salishan 7 ......................................................................................................... 15

6 Ventilation System Discussion ......................................................................................................... 18

7 Conclusions ........................................................................................................................................ 20

8 Recommendations ............................................................................................................................. 21

References................................................................................................................................................. 23

Appendix A. Floor Plans........................................................................................................................... 24

Appendix B. Audit Summaries ................................................................................................................ 26
vi

List of Figures

Figure 1. Salishan housing, prior to reconstruction ............................................................................... 1

Figure 2. Salishan demonstration duplex (left), and control duplex (right).......................................... 3

Figure 3. Exhaust ventilation system controls ........................................................................................ 4

Figure 4. ERV indoor unit (left) and outside terminus (right)................................................................. 4

Figure 5. Infrared image highlighting window vents during blower door induced pressurization 

(wall exterior temperature provided as reference)............................................................................ 5

Figure 6. Thermographic images, indicating leakage at bottom plate to slab intersection (left), and 

attic access hatch (right) ..................................................................................................................... 6

Figure 7. Salishan 7 annual electricity use by housing unit................................................................. 16

Figure 8. Salishan 7 electricity use by billing period ............................................................................ 17

Figure 9. Moisture sensor location (left) and interior detail (right)...................................................... 21

Figure 10. First floor ................................................................................................................................. 24

Figure 11. Second floor............................................................................................................................ 25

Figure 12. Control (left) and demonstration (right) duplexes............................................................... 26

Figure 13. Infrared image of demonstration home under blower door-induced pressurization, 

highlighting fresh air inlet vents per Washington code (wall exterior temperature provided as 

reference) ............................................................................................................................................ 28

Figure 14. Indication of air leakage at bottom plate to slab intersection............................................ 30

Figure 15. Significant air leakage at exterior door due to lack of positive connection between door 

and weather stripping ........................................................................................................................ 30

Figure 16. Significant air leakage at attic access hatch........................................................................ 31

Figure 17. Daikin DHP indoor (left) and outdoor (right) units .............................................................. 31

Figure 18. DHP prefilters before (left) and after (right) cleaning. The filter had been in use for 

roughly a year before cleaning. ........................................................................................................ 32

Figure 19. Hard-wired DHP thermostat, with hourly temperature and relative humidity data logger32

Figure 20. Location of whole-house ventilation fan (left) and lint buildup (right) from ventilation 

fan grille............................................................................................................................................... 33

Figure 21. Whole-house exhaust ventilation control ............................................................................ 33

Figure 22 (Clockwise, from top left) operable fresh air wall port in living room interior, exterior, 

and infrared......................................................................................................................................... 35

Figure 23. ERV indoor unit (left) and outside terminus (right)............................................................. 36

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

List of Tables

Table 1. Envelope Leakage Testing Results (ACH50) .............................................................................. 6

Table 2. Salishan House Characterization................................................................................................ 9

Table 3. Incremental Costs From Salishan 6.......................................................................................... 10

Table 4. Modeled Energy Usage Results (kWh)..................................................................................... 12

Table 5. Comparison of Modeled Results, Window Vents Closed and Open (kWh).......................... 13

Table 6. Source Energy Use and Savings Over Building America Benchmark (MBtu/yr)................. 14

Table 7. Economic Analysis..................................................................................................................... 14

Table 8. Air Inlet Vent Contribution to Envelope Leakage.................................................................... 18

Table 9. Combined House Depressurization.......................................................................................... 19

Table 10. Energy Features of Salishan Demonstration and Control Duplexes .................................. 27

Table 11. Tested Infiltration Rates With Intakes Open and Closed...................................................... 28

Table 12. Air Inlet Vent Contribution to Envelope Leakage.................................................................. 29

Table 13. Combined House Depressurization With Exhaust Fans ...................................................... 37

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

Definitions

ACH50 Air Changes per hour at 50 Pascals

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

AW Area weighted

BIB Blown-in blanket

CFL Compact fluorescent lamp

CFM50 Cubic feet per minute at 50 Pascals

DHP Ductless heat pump

EF Energy factor

ELA Effective leakage area

EqLA Equivalent leakage area

ERV Energy recovery ventilator

HSPF Heating season performance factor

HVI Home Ventilation Institute

IAQ Indoor air quality

IRC International Residential Code

LEED Leadership in Energy and Environmental Design

SEER Seasonal energy efficiency ratio

THA Tacoma Housing Authority

TPU Tacoma Public Utilities

VIAQ Washington State Ventilation and Indoor Air Quality Code

WSEC Washington State Energy Code

WSU Washington State University
ix

Acknowledgments

This work is sponsored in large part by the U.S. Department of Energy Office of Building 

Technology’s Building America Industrialized Housing program under cooperative agreement 

DE-FC36-99GO10478.

The authors would like to thank the following persons and organizations for their contributions 

to this project and paper: Eric Martin, U.S. Department of Energy Building America; Ken 

Eklund and David Hales, Washington State University Energy Program; Bruce Carter, Tacoma 

Public Utilities; Derek Johnson, Walsh Construction; Theresa Weston, DuPont; Don Stevens, 

Panasonic USA; Gary Nelson and Collin Olson, Energy Conservatory.
x

Executive Summary

This project documents market-ready energy solutions to improve the efficiency of new 

affordable housing in the marine climate of Washington State.

The project analyzes the cost effectiveness of energy savings measures installed by a large public 

housing authority in Tacoma, Washington. This first year report focuses on the last of seven 

phases of affordable housing construction; subsequent reports will evaluate the previous phases. 

The construction effort at Salishan is a good example of a not-for-profit housing authority 

utilizing the best available technology to construct highly efficient new housing. The major 

features of the 91 Salishan phase 7 homes, which were constructed in 2009–2010, include:

• Ductless heat pumps (DHPs), providing heat to the first floor, with electric resistance 

heating on the second floor, compared to electric resistance heating the homes in previous 

phases1

• Increased insulation

o R-15 slab perimeter, compared to R-10 in phase 6 homes

o R-23 Blown-in-blanket walls, compared to R-21 batts in phase 6 homes

o R-49 advanced framed (full depth) attic, compared to R-38 standard framing 

(insulation tapered at the heel) in phase 6 homes.

The last four units in the development were selected to demonstrate advanced technologies, 

including:

• R-5 exterior foam sheathing on the walls

• Panasonic energy recovery ventilators (ERVs)

• DuPont liquid-applied house wrap.

This report presents the results of an energy performance and a cost-effectiveness analysis. The 

Salishan phase 7 and demonstration homes were compared to Salishan phase 6 homes built to 

2006 Washington State Energy Code specifications.

2 Predicted annual energy savings (over 

Salishan phase 6) was 19% for Salishan phase 7, and 19%–24% for the demonstration homes

(depending on ventilation strategy). Approximately two-thirds of the savings are attributable to 

the DHP.

Working with the electricity utility provider, Tacoma Public Utilities, researchers conducted a 

billing analysis for Salishan phase 7. Median energy use for the development is 11,000 kWh; 

 1 Some of the larger homes (a four-bedroom duplex design and a five-bedroom single-family home) were equipped 

with two-head DHPs. All of the other homes had single-head DHPs. 2 Per BEopt 1.3, the 2006 Washington State Energy Code shows 21.9% savings over the Building America 

Benchmark.
xi

annual energy costs are $780, with a fair amount of variation depending on the size of the home.

Preliminary analysis of savings between Salishan 7 and previous phases (4–6) suggest savings of 

20%–30%. A more comprehensive comparison between Salishan 7 and previous phases will take 

place in year 2 of this project.
1

1 Introduction

Salishan is a mixed-income neighborhood of Tacoma, Washington, originally built by the federal 

government in 1942 to provide worker housing to support the war effort. The Tacoma Housing 

Authority (THA) managed Salishan for the federal government until the war’s end, and 

afterward, when the federal government gave most of Salishan, with about 880 apartments on 

188 acres, to THA to own and manage as a public housing community. Since construction, 

Salishan has been an important part of the city’s stock of affordable housing; in addition, it has 

been a gateway community—a first home for new immigrants.

By the end of the 1990s, the condition of the housing in Salishan was very poor. At the time of 

construction, long-term durability was not a high priority. In addition, the buildings were not 

well maintained and were falling apart.

Figure 1. Salishan housing, prior to reconstruction

From 2001 to 2011, THA undertook a $225 million effort to demolish and reconstruct Salishan 

in seven phases. New Salishan is a mixed-use neighborhood of affordable and market-rate rental 

units, single-family homes for sale, commercial buildings, and parks, all on new infrastructure

(Tacoma Housing Authority, 2009).

In late 2009, Washington State University (WSU) Energy Program began working with THA, 

Walsh Construction, Tacoma Public Utilities (TPU), and consultant O’Brien and Company on 

the design, construction, and commissioning of Phase 7 of the Salishan development. Phase 7, 
2

which began construction in late 2009, and was completed in late 2010, is composed of 91 lowincome housing units built to ENERGY STAR® standards, and is the first federal Hope VI 

project to achieve Leadership in Energy and Environmental Design (LEED) Platinum. Whereas 

previous phases were heated by electric baseboard units, Salishan 7 homes included ductless heat 

pumps (DHPs). In addition, the Salishan 7 units included improved insulation in the slab 

perimeter, walls, and ceiling.

With support from Building America, WSU and Walsh Construction coordinated the plans for 

the last four units to demonstrate advanced technologies, including exterior foam sheathing and 

Panasonic energy recovery ventilators (ERVs). This package of measures was designed and 

modeled to achieve 30% savings over the Building America Benchmark. In addition, DuPont 

provided liquid-applied house wrap (which has primarily been employed for commercial 

buildings) for the demonstration homes.

WSU coordinated with THA and TPU to collect energy usage data (2-month billing periods) for 

billing analysis.

Research questions:

• What are the performance improvements and cost benefits of the Salishan 7 homes 

compared to Salishan 6 homes, which were built to 2006 state code?

• What are the performance improvements and cost benefits of the demonstration 

technologies compared to homes built to state code?

• How do the different ventilation strategies available to the demonstration home affect the 

performance of those units?

• How does modeled energy use compare to the actual use derived from billing data?
3

2 Energy Audits

In February of 2012, WSU conducted detailed audits of one of the demonstration duplexes, and 

another (control) Salishan 7 duplex with an identical floor plan. The duplexes are located within 

two blocks of each other.

The duplexes are mirrored floor plan, 1,109-ft2

, two-story, two-bedroom, 11⁄2-bath units with a 

common wall separation. The homes are frame construction with trussed attics and perimeter 

insulated slab-on-grade floors. Bedrooms are located on the second floor.

Figure 2. Salishan demonstration duplex (left), and control duplex (right)

Each unit is heated with a single-head DHP with thermostatically controlled baseboard heaters 

located in both bedrooms and the second-floor bathroom. Domestic hot water is provided by 

electric tank water heaters located within the conditioned space.

Whole-house ventilation in the control duplexes is provided by a continuously operating exhaust 

fan. The control duplexes include seven dedicated fresh air intakes per dwelling unit; operable 

trickle vents in the frames of windows in the kitchens, living rooms, bedrooms, and bedroom 

closets; as well as operable wall ports in the living rooms and master bedrooms of both units. All 

fresh air intake vents in both units were found to be in the closed position.

Whole-house ventilation in the demonstration duplexes is provided by the same exhaust fan 

described above; in addition, the demonstration units are outfitted with ERVs, located at the top 

of the stairwell. In one of the demonstration duplexes, the exhaust system was in constant 

operation, with the ERV used very infrequently. In the other duplex, both systems were in 

continuous use.3

 3 The ERVs were a late addition to the demonstration homes. The homes had been permitted and planned to use 

exhaust ventilation fans to meet code requirements; in the end, both systems were installed. According to Walsh 
4

Figure 3 shows the exhaust ventilation system controls, which are only operable by a “key” used 

by THA staff.

Figure 3. Exhaust ventilation system controls

Flow rates were not captured for the ERVs in the demonstration units because it is challenging to 

capture individual supply and exhaust measurements. In both the inside unit and outside terminus 

the supply and exhaust are located side by side; at the outside terminus the issue is compounded 

by the fact that the terminus is located on the second story (see Figure 4). 

Figure 4. ERV indoor unit (left) and outside terminus (right)

 Construction, the demonstration homes were turned over to homeowners with the exhaust system on and the ERV 

off. Homeowners in the demonstration units had their ventilation options explained to them in an occupant manual, 

and via two orientation visits with THA (Johnson, 2012).

Supply air stream

Exhaust air stream
5

The ERVs are rated at 40 CFM for high speed and 20 CFM for low speed. Exhaust fan flow rates 

were measured for all units, for an average of 57 CFM. This is lower than their listed rate of 75 

CFM (at 0.25 in. water column), but well exceeding the code requirement of 45 CFM for 

constant operation.

Under the provisions of the Washington State amended International Residential Code (IRC), 

which replaced the state’s Ventilation and Indoor Air Quality Code (VIAQ) code in 2009, homes 

using exhaust whole-house ventilation systems must provide fresh air to each habitable space.

The fresh air inlets must provide not less than 4 in.2 per habitable space (Washington State 

Building Code Council, 2009). The Salishan homes meet this code requirement through the use 

of window vents. As defined by code, each duplex had four habitable spaces (living and dining 

rooms, and two bedrooms). All of the windows were equipped with air inlet vents; typically, 

homes in Washington utilizing intake vents install one per habitable space.

Figure 5 is an infrared image of one of the demonstration units, highlighting the window vents

during blower door induced pressurization. The window vents are a small thermal short in the 

window frame, and are not considered in National Fenestration Rating Council rating tests of 

window performance. Under typical winter conditions, air may infiltrate on the first floor and 

exfiltrate on the second floor, due to stack effect.

Figure 5. Infrared image highlighting window vents during blower door induced pressurization

(wall exterior temperature provided as reference)
6

The amended IRC requirements allow for the use of ASHRAE Standard 62.2 as an alternate 

route to compliance with state code. ASHRAE 62.2 does not require the use of fresh air inlets for 

exhaust only ventilation (American Society of Heating, Refrigerating and Air-Conditioning 

Engineers, 2007).

Air leakage testing was performed on both of the control and demo duplexes using blower door 

test equipment and infrared thermography. Blower door tests were conducted in two 

configurations: with window vents open and closed. Results of these tests are shown in Table 1.

Table 1. Envelope Leakage Testing Results (ACH50)

Tested House Infiltration Rate

Dwelling Unit CFM50

Vents Open

CFM50

Vents Closed

CFM50

Vents

Control A 520 384 136

Control B 515 411 104

Demo A 500 355 145

Demo B 430 310 120

A visual inspection of air leakage was also performed, using infrared imaging technology (Figure 

6). Although the overall performance of the air barrier in these homes was superior to standard 

framed homes in the region (3.2–3.5 ACH50, compared to 5–7 ACH50 for typical construction), 

infrared inspection revealed air leakage in areas of the thermal enclosure where framing 

assemblies meet and at penetrations. Areas of note included framing intersections, attic hatches, 

windows, and doors, as well as outlets and switches. Similar leakage points were found through 

infrared imagery in both the demo and control duplexes.

Figure 6. Thermographic images, indicating leakage at bottom plate to slab intersection (left), 

and attic access hatch (right)

A complete audit summary is provided in Appendix B.
7

2.1 Homeowner Surveys

As part of the energy audits, researchers surveyed the occupants of the demonstration and control 

homes to assess the occupancy patterns and other factors that might affect electricity use. The 

audits helped inform the modeling effort, and will provide a basis of comparison between 

Salishan 7 and earlier phases in future research.

• With the exception of a large-screen television in one of the control homes, there were no 

unusual electrical loads in any of the homes.

• Occupancy varied significantly among the homes—one of the control units was 

unoccupied 27 hours of the week, and one of the demonstration homes was unoccupied

only 2 hours of the week.

• Homeowners had limited knowledge of the use of the ventilation system. The air inlet 

vents were closed in all homes except one of the demonstration units, where all the inlets 

had been opened by a THA employee. All homes had the exhaust ventilation system 

operating 24 hours a day, 7 days a week (operation was not controllable by the 

occupants). In one of the demonstration homes, the ERV was in constant operation on 

low speed; in the other demonstration home, the ERV was rarely used.

• All homeowners expressed a high degree of satisfaction with the indoor air quality (IAQ) 

in their homes; two respondents to the survey (one control and one demonstration) 

indicated that, while having suffered from allergy symptoms in their previous homes, 

they were symptom free at Salishan.

• The occupants of one of the demonstration homes used the DHP for cooling consistently 

during the summer months; the other occupants said they used it rarely.

• Occupant control of the DHP and baseboard heater varied greatly during the heating 

season. Temperature settings for the DHP ranged from a constant 68°–78°F when 

occupied, set back to 70°F when unoccupied. Baseboard heater use ranged from being on 

only in bedrooms at night to constant use when the house was occupied.

The homeowners were generally satisfied with the efficiency of their homes (based on the 

energy bills) and their overall comfort. There were some complaints about the uneven 

distribution of heat downstairs (DHP) and the difficulty in maintaining a steady and 

comfortable heat upstairs.
8

3 Modeling Methods

3.1 Energy Analysis

Researchers used EnergyGauge USA version 2.8.05 for the energy use simulation modeling

(Florida Solar Energy Center, 2012).

Modeling compared the predicted performance of:

• Homes built in phase 6, to the 2006 Washington State Energy Code (WSEC)

• Homes built in phase 7, under the 2009 WSEC, built to ENERGY STAR and LEED 

Platinum levels, with DHPs

• Homes built in phase 7, with additional demonstration technologies.

Since the demonstration homes had both exhaust air ventilation and ERVs, researchers decided 

to model the homes under three scenarios: as if both systems were operational at the same time, 

as if a home had either the exhaust system or the ERV operating.

The homes’ envelope and performance parameters are specified in Table 2.

Envelope leakage rates for Salishan 7 and demonstration models were based on field testing, 

with the window vents open; for Salishan 6, envelope leakage was assumed to be 7.0 ACH50, per 

2006 WSEC assumptions. In year 2 of the project, researchers will determine envelope leakage 

for phases 1–6 via blower door testing.

Initially, BEopt was not used, since at the time the analysis was conducted, BEopt had 

limitations in the ability to model multifamily dwellings, DHPs, and combinations of different 

heating systems.

Subsequent to the initial analysis, the National Renewable Energy Laboratory released a version 

of BEopt that addressed these issues (National Renewable Energy Laboratory, 2012). WSU 

conducted a benchmarking analysis of Salishan 7 and demonstration units, and included WSEC 

2006 and 2009 for reference.
9

Table 2. Salishan House Characterization

Measure Salishan 6 Salishan 7 Salishan 7 Demo

Slab Insulation R-10 perimeter R-15 perimeter4 R-15 perimeter

Wall Insulation5 R-21 batt

(U-.057)

R-23 BIBa

(U-0.052)

R-23 BIB + R-5 

foam (U-0.040)

Windows .35 AWb U-factor 0.29 AW U-factor 0.29 AW U-factor

Ceiling R-38 standard 

framing (U-.030)

R-49 advanced

framing (U-0.020)

R-49 advanced 

framing (U-0.020)

Space Heating Baseboard 

(5.5 kW)

DHP

9.1 HSPFc/18 SEERd

(1.5 ton)

DHP

9.1 HSPF/18 SEER

(1.5 ton)

Thermostat Set Points 68°F heating

78°F cooling

68°F heating

78°F cooling

68°F heating

78°F cooling

Water Heating 0.95 EFe 0.95 EF 0.95 EF

Lighting 100% CFLf 100% CFL 100% CFL

Dishwasher ENERGY STAR ENERGY STAR ENERGY STAR

Refrigerator ENERGY STAR ENERGY STAR ENERGY STAR

Clothes Washer Standard, top load ENERGY STAR, 

front loaded

ENERGY STAR, 

front loaded

Ventilation VIAQ compliant6 62.2 compliant 

exhaust

62.2 compliant 

exhaust and ERV7

Envelope Leakage 7.0 ACH50 3.5 ACH50 3.2 ACH50

ENERGY STAR No Yes Yes

LEED No Yes Yes

a Blown-in blanket

b Area weighted

c Heating season performance factor

d Seasonal energy efficiency ratio e Energy factor

f Compact fluorescent lamp 

3.2 Economic Analysis

Incremental cost data were collected from Walsh Construction for the energy efficiency 

measures (incremental costs from Salishan 6). In addition, O’Brien and Company provided cost 

data for Northwest ENERGY STAR and LEED certifications. These costs are shown in Table 3.

The wholesale incremental cost for windows with inlet vents is $16.32 each, which is included as 

part of the incremental cost for the window package (Scott, 2012). For the floor plan used for the 

 4 Modeled as R-10, due to limitations within software. 5 Each scenario was also modeled with an R-11 party wall (U-.093) 6 Per VIAQ. Requirements allow for intermittent ventilation, minimum 8 hours per day, at rates less than ASHRAE 

62.2 requirements. 7 Exhaust flows were added together, and recovery efficiency reduced as a weighted average of total fan flow.
10

demonstration and control homes, this amounts to almost $100 (six windows) in excess of code 

requirements, before markup.

Using the results from the EnergyGauge USA analysis, researchers conducted an economic 

analysis of the energy efficiency measures, including simple payback and monthly cash flow.

Table 3. Incremental Costs From Salishan 6

Salishan Demo

Salishan 7 As Built Exhaust Only ERV Only

Slab, Wall Cavity and Ceiling 

Insulation8 $1,261 $1,261 $1,261 $1,261

R-5 Exterior Foam on Walls – $350 $350 $350

Window Upgrade $310 $310 $310 $310

Baseboard to DHP $3315 $3315 $3315 $3315

Ventilation9 – $1050 – $426

Clothes Washer $341 $341 $341 $341

ENERGY STAR 

Northwest Certification10 $364 $364 $364 $364

LEED Certification7 $473 $473 $473 $473

Total Incremental Cost $6,064 $7,464 $6,414 $6,840

 8 Insulation contractor provided package cost only, not individual measure costs.

9 Exhaust only ventilation system cost was $624; ERV cost was $1,050. The “as built” scenario included both 

systems; the other two demonstration scenarios included either the exhaust fan or the ERV. 10 Includes design review, multiple on-site inspections and testing, ongoing technical assistance, submittal fees, and 

travel.
11

4 Billing Analysis Methods

TPU provided electricity use and consumption data for all 91 housing units in Salishan 7 along 

with the premise number, address, and change in account dates (signifying a change in 

occupancy). Data were provided for the period from June 2010 through February 2012. Most of 

the housing units were not occupied until later in 2010 or early 2011, so the data for a unit began

when it was occupied. Electricity billing data are for 2-month periods.

Annual electricity use and costs were calculated for the period February 2011 through February 

2012. Researchers adjusted electricity use to 365 days for each unit to account for any 

differences in meter reading dates (period lengths) or for the few units that did not have quite a 

full year of data. Researchers did not account for any changes in occupancy during this period. 

Researchers also calculated electricity use and cost for the six billing periods during this annual 

analysis period (from February 2011 to February 2012), adjusting electricity use so that the 

length of the billing period was 60 days.

The annual and billing period electricity use and cost were calculated for each housing unit. 

Aggregate electricity use and use by square foot were calculated for all the housing units, by type 

of unit, and by number of bedrooms. Two units were dropped from the analysis because they had 

very low electricity use. One of these was designated as the manager’s unit. Researchers suspect 

that these units were not fully occupied or that there was an error in matching the utility data to 

the unit, so the analysis was based on 89 of the 91 housing units in Salishan 7.

TPU also provided electricity billing data for the housing units in Salishan 4, 5, and 6. Data 

covered the period from December 2007 (when the first units in Salishan 4 began to be occupied) 

through February 2012. Researchers used these data to make a preliminary comparison between 

the annual electricity use in Salishan 7 with these other communities. This preliminary analysis 

does not account for differences in billing period lengths, changes in occupancy, differences in 

housing characteristics, or other data quality issues. It is intended only to give an early indication 

of any differences in electricity use between the units in Salishan 7 and the other Salishan 

communities. 
12

5 Results

5.1 Modeling

Table 4 presents the results from the EnergyGauge modeling.

Table 4. Modeled Energy Usage Results (kWh)

Salishan 

6

VIAQ

Salishan 

6

62.2

Salishan 

7

BIB

Salishan 

7

DHP

Salishan 7 Demo

As 

Built11 Exhaust ERV

Heating 4,360 5,430 4,394 1,925 1,800 1,740 1,297

Cooling 1 0 0 17 13 13 9

Mechanical 

Ventilation 54 169 174 158 342 159 176

Water Heating 3,043 3,046 2,878 2,878 2,878 2,878 2,878

Lighting 360 360 360 360 360 360 360

Appliances and 

Miscellaneous 5,259 5,259 5,210 5,210 5,210 5,210 5,210

Total 13,077 14,264 13,016 10,548 10,603 10,360 9,930

Increased Energy 

Use for Open 

Vents12

19 29 12 99

% Savings Over 

Salishan 6

(VIAQ)

0% 19% 19% 21% 24%

% Savings Over 

Salishan 6

(62.2)

9% 26% 26% 27% 30%

% Savings Over 

Salishan 7 –1% 2% 6%

The Salishan 6 homes are modeled with VIAQ-compliant ventilation, reflecting their real-world 

configuration; these are the energy usage numbers used in the economic analysis. They are also 

modeled with 100% on-time ventilation to ASHRAE 62.2 levels to provide an “apples to apples” 

comparison with the Salishan 7 models. Without this adjustment, the savings from the Salishan 7 

improvements are offset by the costs of increased ventilation.

The Salishan 7 homes are modeled both with the DHP and with baseboard heat only to illustrate 

the contribution of the DHP to the savings for the Salishan 7 package. Comparing the Salishan 7 

 11 Assumes 100% runtime for both exhaust ventilation and ERV. 12 As noted above, the homes were tested both with window vents open and closed. The air leakage inputs for the 

modeling were with vents open, per specifications for the ENERGY STAR Homes Northwest Quality Assurance 

protocols. The models were also run with air leakage inputs reflecting vents closed; this row shows the difference 

between the two scenarios.
13

model to the Salishan 6 model with 100% runtime ventilation, the DHP accounts for 

approximately two-thirds of the overall savings, with the shell measures accounting for the 

additional one-third (this analysis doesn’t account for the interactive effects between the shell 

and the DHP).

In EnergyGauge, heat pumps are assumed to have some level of backup resistance heat, typical 

for a ducted central heat pump. This scenario does not likely match the hybrid DHP/baseboard 

configuration used in the Salishan homes. Given that the homeowner surveys indicated a high 

level of use of the electric resistance heaters in the bedrooms, the homes would be expected to 

perform somewhere between the Salishan 7 baseboard and DHP modeled results.

The demonstration measures seem to have less impact, and are somewhat dependent on the 

ventilation strategy used. The “as built” case is overventilated (100% over IRC requirements), 

which masks the savings from the demonstration technologies.

As noted above, EnergyGauge USA does not currently have the capability of modeling slab 

perimeter insulation at higher than R-10. Researchers used two additional tools, REM/Rate 

(Architectural Energy Corporation, 2012) and the Simple Energy and Enthalpy Model (Ecotope 

Inc., 2012), to make assessments of the impact of this upgrade. This analysis suggested annual 

savings of 89–147 kWh for the increased perimeter insulation; since these estimates were 

conducted outside of the EnergyGauge analysis, and were not considered significant drivers for 

the economic analysis, they are not included in the table.

Table 5 compares Salishan 7 modeled results (with window vents open) to modeled results with 

the vents closed. The overall energy impact of the added leakage from the window vents is 

negligible; the ERV case shows the most impact, at 1% of total energy use.

Table 5. Comparison of Modeled Results, Window Vents Closed and Open (kWh)

Salishan 7 Demo

Salishan 7 As Built Exhaust ERV

Vents Closed 10,548 10,603 10,360 9,930

Vents Open 10,567 10,632 10,372 10,029

Increased Energy Use 

From Open Vents 19 29 12 99

Table 6 provides the benchmarking results from BEOpt version 1.3.
14

Table 6. Source Energy Use and Savings Over Building America Benchmark (MBtu/yr)

Case Heating Cooling Hot 

Water Other

Total

Energy 

Use

Source 

Energy 

Savings

Building America

Benchmark 21.01 1.51 42.03 78.94 143.49 –

Salishan 7 9.47 0.83 38.48 68 116.78 28.0%

Salishan 7 With Foam 8.44 0.76 38.48 67.95 115.63 28.7%

Salishan Demo 6.38 0.89 38.46 70.84 116.57 28.1%

Demo With Exhaust 8.31 0.76 38.48 67.95 115.5 28.8%

2006 WSEC 16.34 1.21 38.49 70.54 126.58 21.9%

2009 WSEC 13.47 0.97 38.49 70.36 123.29 24.0%

5.2 Economic Analysis

Table 7 provides a summary of energy savings, simple payback, and monthly cash flow, 

assuming an electricity rate of $0.08/kWh. Numbers in red indicate a negative cash flow 

(monthly energy savings versus increased mortgage payment.)

Table 7. Economic Analysis

Salishan 6

(VIAQ) Salishan 7

Demo

Exhaust 

and ERV

Exhaust 

Only

ERV 

Only

Total Incremental Cost 

(Table 4) – $6,064 $7,464 $6,414 $6,840

Modeled Annual kWh Usage 

(Table 5) 13,077 10,548 10,603 10,360 9,930

Annual Energy Savings (kWh) – 2,511 2,456 2,699 3,129

Annual Energy Savings ($) – $201 $196 $216 $250

Payback (Years) – 30 38 30 27

Monthly Energy Savings – $17 $16 $18 $21

Monthly Loan Payment

30 Year, 7%13 – $42 $52 $45 $48

Monthly Loan Payment

30 Year, 3%12 – $18 $22 $19 $21

Monthly Loan Payment

30 Year, 0%12 – $17 $21 $18 $19

Incremental Cost for 

Positive Cash Flow, 7% – $2,391 $2,339 $2,570 $2,980

Incremental Cost for 

Positive Cash Flow, 3% – $5,580 $5,458 $5,998 $6,953

Incremental Cost for 

Positive Cash Flow, 0% – $6,026 $5,894 $6,478 $7,510

 13 Incremental cost of improvements.
15

In no case is the improvement package cost effective at market-available financing (the interest 

rate for Salishan 7 was 7%14) (Schur, 2012). With both ventilation systems operating, the 

demonstration home will not achieve positive cash flow under any financing scenario, given the 

additional cost of the dual ventilation system, and its negative impact on the performance of the 

home.

As indicated in the table, a 30-year time frame was used for the cash flow analysis; the minimum 

simple payback is 27 years. The expected measure lives of the envelope measures sit 

comfortably within these time frames; equipment, including the DHP and ventilation system,

does not. According to the Northwest’s Regional Technical Forum, a typical lifetime for DHPs is 

20 years (Northwest Power and Conservation Council, 2012). In order to achieve a 20-year 

payback, the cost of energy would need to be $0.19/kWh for the best case (demonstration home 

with ERV only) and $0.26/kWh for the worst case (demonstration home with both systems 

operating.)

The certification costs for LEED and ENERGY STAR represent 10%–13% of the overall 

package costs. If these are taken out of the incremental costs, the Salishan 7 energy package 

(nondemonstration and the demonstration home with ERV only) reaches positive cash flow at a 

3% interest rate, which is not unheard of in today’s market. This is not to suggest that the costs

of the ENERGY STAR and LEED certifications should be removed from the overall costs of 

these packages. The decision to employ the technologies seen in Salishan 7 and the 

demonstration duplex are in large part due to the engagement of the ENERGY STAR/LEED 

verifier. Rather, the point is that as these technologies become more common and are integrated 

into code or recommended guidelines, and not part of voluntary programs like ENERGY STAR 

or LEED, their justification from a cost-benefit perspective improves.

Beyond the economic analysis, other, less tangible benefits of the Salishan 7 and demonstration 

measures should be considered. In the demonstration homes, the ERV provides added 

supplemental ventilation, while the exterior foam insulation provides added protection against 

condensation and wind-driven rain that cause mold and mildew.

5.3 Billing Analysis of Salishan 7

The average annual electricity use of the Salishan 7 housing units is 11,380 kWh and the median

use is 11,000 kWh. The average annual electricity cost is $790 (median is $780).

15 There is a fair 

amount of variation in the electricity use from the highest to the lowest user (more than a factor 

of 4), but most households have annual electricity use of 8,000–14,000 kWh (Figure 7).

 14 THA pays for the loan; residents pay the energy bill. 15 Eleven of the Salishan 7 residents are on the TPU Low Income Elderly Rate. The rest pay standard rates. Some of 

these customers are on a Paygo system where they add money to their account as needed.
16

Figure 7. Salishan 7 annual electricity use by housing unit

The electricity use by billing period profile shows the average electricity use for each billing 

period along with the standard deviation and the high and low values (Figure 8). The billing 

period profile for Salishan 7 is relatively flat. For low and average users, there is not a large 

difference in electricity use between warmer and colder periods. The difference in electricity use 

between high (StdHi line) and low (StdLow line) electricity users appears to be largely due to 

differences in base (nonheating) electricity use. These results suggest that these housing units are 

very efficient when it comes to heating use. One caution in interpreting these results is the 2-

month billing periods tend to reduce variation in the electricity use profile because they mix cold 

weather periods with warmer periods (a 2-week cold snap will show up more clearly on a 

monthly bill than on a 2-month bill). 
17

Figure 8. Salishan 7 electricity use by billing period
18

6 Ventilation System Discussion

The ventilation system used for the nondemonstration homes at Salishan 7 exceeds IRC flow 

requirements by 22%. The addition of the ERV in the demonstration homes provides an 

additional ventilation option, though at high speed, the ERV would be slightly under code flow 

requirements. As shown in the energy savings analysis, the ERV provides the best energy 

performance, though at a higher initial cost.

The exhaust ventilation control strategy used at Salishan 7 ensures that the ventilation system 

will be left on, but may be in conflict with code requirements. The Washington State amended 

IRC requires that ventilation system controls be “readily accessible to the occupant.” ASHRAE 

Standard 62.2-2007 has similar requirements. The ventilation controls used at Salishan are not 

readily accessible to occupants, unless the requirement can be interpreted to allow for a call to 

THA maintenance staff. Experience has shown that, given the opportunity to shut off a home’s 

ventilation system, many homeowners will do so, compromising the home’s ability to provide 

acceptable IAQ. The approach taken at Salishan (essentially “turn it on and leave it on”) does not 

subject the home’s IAQ to the whim of the homeowner, and is worth additional consideration by 

the Washington State Building Code Council and ASHRAE 62.2 committee.

The configuration and operation of the window vents are also worth discussion. Table 8 shows 

the envelope leakage impacts of the window vents (from Table 1), and provides three different 

ways of interpreting those results.

Table 8. Air Inlet Vent Contribution to Envelope Leakage

Tested House Infiltration Rate

Dwelling Unit CFM50

Vents

CFM10

Vents

Deemed

Equivalent

Leakage

(in.2)

ELA16

Vents 

(in.2)

EqLA17

Vents 

(in.2)

Control A 136 48 19.2 7.47 14.04

Control B 104 37 14.8 5.71 10.74

Demo A 145 51 20.4 7.96 14.97

Demo B 120 42 16.8 6.59 12.39

The Washington amended IRC requirements deem “any inlet or combination of inlets which 

provide 10 CFM at 10 Pascals as determined by the Home Ventilation Institute Air Flow Test 

Standard...HVI 901...equivalent to 4 square inches of net free area.” Under this provision, the 

tested Salishan homes would meet or exceed the IRC requirements (16 equivalent square inches), 

 16 ELA – Effective leakage area – area leakage calculation developed by Lawrence Berkeley Laboratory, defined as 

the area of a nozzle-shaped hole that would leak the same amount of air as a building under a pressure of 4 Pascals. 17 EqLA – Defined by researchers at the Canadian National Research Council as the area of a sharp edged 

orifice...that would leak the same amount of air as a building does at a pressure of 10 Pascals (Energy Conservatory, 

2007).
19

with the exception of control B. Note that there is a discrepancy between the IRC deemed 

equivalency and the ELA and EqLA calculations, which are generally accepted assessments of 

envelope leakage area.18

Regardless of the calculation of net free area employed, it is worth noting that the Salishan 7 

homes had twice the number of window vents typically observed in new construction. It is also 

worth noting that the vents were closed in all but one home (where they had been opened by 

THA staff).

The use of window vents as part of a whole-house ventilation strategy is controversial; there is 

disagreement between state code requirements and ASHRAE 62.2 regarding their necessity with 

an exhaust only ventilation strategy. There are added costs for windows with vents, both in 

materials and the added cost of heating outside air.

Control B was tested to determine the effect on house pressure with reference to the outdoors 

when exhaust fans are activated. Table 9 represents the combined house depressurization with 

reference to outside with the introduction of each exhaust ventilation system starting with the 

whole-house fan.

Table 9. Combined House Depressurization

House Depressurization With Reference to Outside

Fresh Air Intake Closed 

(Pascals)

Fresh Air Intake Open 

(Pascals)

No Ventilation –2.0 0.0

Whole-House Fan –6.7 –5.5

+ First-Floor Bath Fan –12.2 –8.0

+ Second-Floor Bath Fan –23.1 –15.0

+ Kitchen Range Fan on HIGH –32.3 –24.2

+ Dryer –41.2 –31.3

The results of this testing help to provide support to organizations like Building America, 

Washington State Building Code Council, and ASHRAE in discussions associated with the use 

of air inlet vents, especially in tight homes.

 

18 The Washington State Building Code Council has expressed an intent to remove the HVI 901 reference from the 

next version of the amended IRC requirements pertaining to ventilation.
20

7 Conclusions

The project demonstrated significant modeled savings (26% when the change in ventilation 

runtime is discounted) for improvements from 2006 WSEC to the technologies used in Salishan 

7. Preliminary billing data comparing Salishan 7 to previous phases seem to support this 

analysis, though more analysis is needed to directly compare units of similar layout. WSU is 

working with TPU to obtain hourly utility data for Salishan 7 and earlier phases. The DHP 

represents the single most significant improvement to the modeled energy savings for Salishan 7.

The viability of the energy efficiency improvements, from a cost-benefit perspective, is limited 

due to the lack of availability of lower interest financing.

The additional demonstration technologies seem to provide less appreciable benefit over the 

Salishan 6 homes, though this is dependent to a large extent on the ventilation strategy adopted 

by the homeowner (and their ability to change said strategy based on the home’s configuration).

Demonstration homes using the ERV as the sole whole-house ventilation system showed the 

highest modeled savings; a demonstration home operating with both systems used sufficient 

energy to mask the savings from the additional measures.

Technologies such as the ERV, exterior foam, and the liquid-applied house wrap may have 

indoor air quality and moisture mitigating benefits not readily apparent from the savings 

analyses. The benefits of ENERGY STAR and LEED certifications, including IAQ, durability,

and overall resource efficiency, are also not captured in the economic or energy efficiency 

analyses (though the costs are), but also need to be taken into account.

The participant surveys indicated that the homeowners were generally pleased with the comfort 

and affordability of their homes post-retrofit. The surveys identify some issues with inconsistent 

heat in the DHP zone.

The use of a single-zone ERV may limit its effectiveness in rooms removed from the house core 

(bedrooms in particular). The DHP has similar issues in its ability to effectively heat and cool 

rooms behind closed doors.
21

8 Recommendations

More research is needed to investigate the spatial distribution effectiveness of both DHPs and 

zonal ERVs (for example, determining optimum thermostat settings, leaving doors open to 

reduce backup heating use, and installing fans to move air from one room to another to equalize 

temperatures).

Research is also needed to provide guidance to homeowners on the best use of DHP and ERV 

technologies. Education of homeowners, including baseboard and DHP set points, and the need 

to leave bedroom doors open when possible, is necessary if these technologies are to be used to 

their best advantage, save energy, and provide the best IAQ.

From a public policy perspective, it is worth investigating how housing authorities and other 

low-income focused organizations could have access to lower financing to provide maximum 

benefit.

Additional investigations into the various ventilation strategies available in the demonstration 

homes will provide occupants and THA with a ventilation strategy that provides good IAQ with 

lower operational costs.

WSU coordinated with DuPont to install monitoring equipment in the wall assemblies, to study 

the effectiveness of the liquid-applied house wrap on limiting moisture in the wall (Figure 9).

The results of this monitoring will be provided by DuPont in the future.

Figure 9. Moisture sensor location (left) and interior detail (right)

During future site visits, researchers will use Energy Conservatory’s Flow Blaster for ERV and 

exhaust fan measurements. The Flow Blaster was designed in part to measure the low flows 

associated with ERVs. Researchers will also work with Energy Conservatory and the ERV 

manufacturer to determine the best means of testing the ERV, given the grille configuration.
22

Researchers will also use Energy Conservatory’s TECLOG software to perform more detailed 

assessments of the impact of the fresh air vents on Salishan 7 and earlier developments.
23

References

American Society of Heating, Refrigerating and Air-Conditioning Engineers. (2007). Ventilation 

and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. Standard 62.2-

2007.

American Society of Heating, Refrigerating and Air-Conditioning Engineers. (2012). Minutes of 

June, 2012 Meeting of Standing Committee 62.2, Ventilation and Acceptable Indoor Air 

Quality in Low-Rise Residential Buildings.

Architectural Energy Corporation. (2012, June). REM/Rate. version 12.99. Boulder, Colorado: 

AEC.

Ecotope Inc. (2012). Simple Energy and Enthalpy Model. SEEM, version 92. Seattle, WA: 

Ecotope, Inc.

Florida Solar Energy Center. (2012). EnergyGauge USA. v 2.80.5. Cocoa Beach, Florida.

Johnson, D. (2012, June 20). Salishan superintendent, Walsh Construction. (A. Gordon, 

Interviewer)

National Renewable Energy Laboratory. (2012). BEOpt. (v. 1.3e+). Golden, Colorado.

Northwest Power and Conservation Council. (2012, May 15). RTF Unit Energy Savings (UES) 

Measures and Supporting Documentation. Retrieved June 29, 2012, from Regional 

Technical Forum: http://www.nwcouncil.org/energy/rtf/measures/Default.asp

Schur, R. (2012, June 19). Senior Project Manager, Tacoma Housing Authority. (M. Lubliner, & 

A. Gordon, Interviewers)

Scott, M. (2012, June 27). Production Home Division Sales, Milgard Inc. E-mail 

Correspondence.

Tacoma Housing Authority. (2009, March 6). Salishan's Redevelopment. Retrieved June 19, 

2012, from Tacoma Housing Authority: 

http://www.tacomahousing.org/Salishan/history.html

Washington State Building Code Council. (2009). Amendments to the International Mechanical 

Code.
24

Appendix A. Floor Plans

Figure 10. First floor
25

Figure 11. Second floor
26

Appendix B. Audit Summaries

Introduction

Phase 7 of the Salishan development began construction in 2009. All units were occupied early 

in 2011. This phase of construction consisted primarily of two- and three-bedroom duplexes and 

triplexes. In February of 2012 WSU Energy Program conducted detailed audits of four twobedroom duplexes identical in floor plan (model D#3). Both duplexes are located within two 

blocks of one another in the Salishan development. One pair of duplexes represents the control in 

this study; the other two represent the demonstration homes (see Figure 12)

The D#3 model duplex consists of mirrored floor plan, 1,109 ft2

, two-story, two-bedroom, 11⁄2-

bath units, with a common wall separation. The homes are stick framed with trussed attics and 

slab-on-grade floors. Bedrooms are located on the second floors. All units are heated with a 

single-head Daikin DHP (RXS18DVJU) with 500-W thermostatically controlled baseboard 

heaters located in both bedrooms and the second-floor bathrooms. Domestic hot water is 

provided by electric tank type water heaters located within the conditioned space.

Figure 12. Control (left) and demonstration (right) duplexes

The above-grade walls are constructed with standard framing and insulated to R-23 with BIB 

fiberglass insulation. The walls are sheathed to the exterior with 1⁄2-in. plywood/oriented strand 

board sheet goods, with a continuous weather barrier installed between the wall sheathing and 

cement fiberboard lap siding. Interior walls are sheathed in 1⁄2-in. gypsum wall board. Roof 

structures are primarily advanced framed, raised heel trusses containing ventilated attic space 

insulated to R-49. There is 50 ft2 of roof area that is framed with 14-in. single rafter joists, 

ventilated, and insulated to R-38. Slab floors are insulated to 2 ft around the entire perimeter with 

R-15 rigid insulation. Window U-factors are 0.28. The UA of the typical D#3 floor plan duplex 

is 123, 17% lower than the 2009 International Energy Conservation Code target of 147.1.

Infrared thermography did not indicate significant voids or degradation of exterior wall 

insulation.
27

The demonstration duplex includes the installation of 1-in. (R-5) extruded polystyrene 

continuous insulation. Additionally, a liquid-applied weather barrier has been installed in place 

of the typical weather barrier on this duplex.

The energy features of the control duplex are typical for all nondemonstration homes at Salishan 

7. Table 10 provides a comparison of the energy features of the control and demonstration 

duplexes.

Table 10. Energy Features of Salishan Demonstration and Control Duplexes

Measure Salishan 6 Salishan 7 Salishan 7 Demo

Slab Insulation R-10 perimeter R-15 perimeter R-15 perimeter

Wall Insulation19 R-21 batt

(U-.057)

R-23 BIB

(U-0.052)

R-23 BIB + R5 foam 

(U-0.040)

Windows .35 AW U-factor 0.29 AW U-factor 0.29 AW U-factor

Ceiling R-38 standard framing 

(U-.030)

R-49 advanced 

framing (U-.020)

R-49 advanced 

framing (U-.020)

Space Heating

Baseboard 

(5.5 kW)

DHP

9.1 HSPF/18 SEER

(1.5 ton)

DHP

9.1 HSPF/18 SEER

(1.5 ton)

Thermostat Set 

Points

68°F heating

78°F cooling

68°F heating

78°F cooling

68°F heating

78°F cooling

Water Heating 0.95 EF 0.95 EF 0.95 EF

Lighting 100% CFL 100% CFL 100% CFL

Dishwasher ENERGY STAR ENERGY STAR ENERGY STAR

Refrigerator ENERGY STAR ENERGY STAR ENERGY STAR

Clothes Washer Standard, top load ENERGY STAR, 

front loaded

ENERGY STAR, 

front loaded

Ventilation VIAQ compliant20 62.2 compliant 

exhaust

62.2 compliant 

exhaust and ERV

Envelope Leakage 7.0 ACH50 3.5 ACH50 3.2 ACH50

ENERGY STAR No Yes Yes

LEED No Yes Yes

 19 Also includes R-11 party wall (U-.093) 20 Per VIAQ. Requirements allow for intermittent ventilation, minimum 8 hours per day, at rates lower than 

ASHRAE 62.2 requirements.
28

Findings

Figure 13. Infrared image of demonstration home under blower door-induced pressurization, 

highlighting fresh air inlet vents per Washington code

(wall exterior temperature provided as reference)

Air leakage testing was performed on the control and demonstration duplexes using blower door 

test equipment and infrared thermography. Blower door tests were conducted with fresh air 

intakes open and closed. Table 11 shows blower door infiltration rate test results of all four 

dwelling units audited with and without fresh air intake vents open.

Table 11. Tested Infiltration Rates With Intakes Open and Closed

Tested House Infiltration Rate

Dwelling Unit CFM50

Intakes Open

CFM50 Intakes 

Closed

CFM50

Intakes

Control A 520 384 136

Control B 515 411 104

Demo A 500 355 145

Demo B 430 310 120
29

All dwelling units were tested without neutralizing pressure difference between adjoining 

common wall units, and thus reflect infiltration from the adjoining dwelling unit. True leakage 

rates to exterior are assumed to be less than these test results reflect. These measured leakage 

rates are considerably less than the current maximum leakage rate (4.0 ACH50) required by the 

Northwest ENERGY STAR Homes program for gas- and heat pump-heated homes.

The whole-house ventilation code in Washington State requires that homes using exhaust wholehouse ventilation systems introduce fresh air to each habitable space. The fresh air inlets must 

provide not less than 4 in.2 of net free area per habitable space, or 10 CFM at CFM10 per 

habitable space. All habitable spaces within both the demonstration and the control homes had 

two inlet vents with exception of the kitchen, which only had one. According to blower door test 

results with and without the vents open, the calculated EqLA was, on average, approximately 

82% of what is required per code. However, the calculated CFM10 is 111% of what is required 

per code.

These calculated intake vent infiltration rates are based upon blower door test results and should 

be considered estimates. There was up to 30% variability in tested infiltration rates between the 

four tested dwelling units. A bigger sample would be needed to make more accurate assumptions 

of intake vent infiltration rates for the Salishan 7 development. Table 12 shows the envelope 

leakage impacts of the window vents, and provides three different ways of interpreting those 

results.

Table 12. Air Inlet Vent Contribution to Envelope Leakage

Blower Door Test Calculated Intake Vent 

Infiltration Rate Code Requirement

Dwelling Unit

Habitable 

Spaces per 

Dwelling Unit

CFM50 VentsCFM10 Vents

Deemed

Equivalent

Leakage 

(in.2

)

ELA Vents 

(in.2

)

EqLA Vents 

(in.2

)

Minimum

Code Required 

Vent Net Free 

Area (in.2

)

Minimum

Code Required 

Vent CFM10

Control A 4 136 48 19.2 7.47 14.0 16 40

Control B 4 104 37 14.8 5.71 10.7 16 40

Demo A 4 145 51 20.4 7.96 15.0 16 40

Demo B 4 120 42 16.8 6.59 12.4 16 40

A visual inspection of air leakage was performed with infrared imaging technology from the 

interior of the structure while the blower door equipment held the interior pressure at –50 

Pascals. Although the overall performance of the air barrier in these homes was superior to 

standard stick-framed homes in the region, this inspection revealed air leakage in the expected 

areas of the thermal enclosure where framing assemblies meet and at penetrations (see Figure 14

through Figure 16). Areas of note included framing intersections, attic hatches, windows, and 
30

doors, as well as outlets and switches. Similar leakage points were found through infrared 

imagery in both the demonstration and control duplexes.

Figure 14. Indication of air leakage at bottom plate to slab intersection

Figure 15. Significant air leakage at exterior door due to lack of

positive connection between door and weather stripping
31

Figure 16. Significant air leakage at attic access hatch

Single-zone 15 kBtu/h Daikin (RXS15DVJU) DHPs were installed in both the demonstration

and control duplexes as the primary heating system (see Figure 17). The interior DHP air 

handlers were mounted within the top 4 in. of an exterior wall with the exterior DHP compressor 

located on the other side of the same wall at roughly the same height as the interior air handler.

This configuration allows for efficient operation and installation, reduces line set and electrical 

run length, and ensures greater protection from physical damage. The heat pumps are controlled 

by hard-wired programmable thermostats mounted in central and accessible locations on the first 

floors of both homes.

Figure 17. Daikin DHP indoor (left) and outdoor (right) units
32

Daikin recommends filters be cleaned every 2 weeks (see Figure 17). Cleaning of the filters is 

performed with vacuuming or washing under warm water (see Figure 18). The heat pump also 

has a deodorizing air filter that the manufuacturer recommends being washed with warm water 

every 6 months and replaced every 3 years. Traditional forced-air heating system manufacturers

typically recommend filter replacement monthly, and in most cases these filters are not reusable.

Figure 18. DHP prefilters before (left) and after (right) cleaning. The filter had been in use for 

roughly a year before cleaning.

All bedrooms and bathrooms are equipped with 500-W electric baseboard heaters that are all 

independently thermostatically controlled (see Figure 19). Domestic hot water is provided by 

0.95 EF electric 50-gal water heaters located in a utility closet within the conditioned space. 

Lighting in all homes is 100% high efficacy. The majority of the fixtures have Edison bases 

containing CFLs, but there are a few pin-based fixtures. 

Figure 19. Hard-wired DHP thermostat, with hourly temperature and relative humidity data logger
33

Whole-house ventilation in both control units is provided by an exhaust only system (Figure 20

and Figure 21)). These systems are powered by Panasonic FV-08VQ2 exhaust fans. These fans 

are listed in the HVI database as having the capacity to provide 75 CFM at 0.25 in. of static 

pressure while drawing 20 W. These fans are located in the laundry closet on the first floor and 

are controlled by a keyed lockout switch. The laundry closet is enclosed by louvered bifold 

doors. The whole-house fans in both control duplex units are operated continuously and were 

tested with a flow box to provide 53 and 57 CFM of exhaust ventilation. These flow rates are 

both higher than the 45 CFM prescribed by Washington State whole-house ventilation 

requirements for continuous operation.

Figure 20. Location of whole-house ventilation fan (left) and 

lint buildup (right) from ventilation fan grille

Figure 21. Whole-house exhaust ventilation control
34

This model of exhaust fan is rated for continuous operation and has a 60,000-hour warranty. 

However, it was observed during the site visit/audit that the whole-house exhaust fan grill 

contained considerable amounts of lint due to its proximity to the clothes dryer. 

The whole-house exhaust ventilation system for the control duplexes includes seven dedicated 

fresh air intakes per dwelling unit. These intakes are provided by operable trickle vents located in 

the frames of windows in the kitchens, living rooms, bedrooms, and bedroom closets.

Additionally there are also operable wall ports in the living rooms and master bedrooms of both 

units in place of an operable trickle vent in the street facing (west) windows. As seen in the 

infrared image in Figure 11, use of this through the wall ventilation approach compromises the 

envelope’s air and thermal barrier due to the placement of fresh air duct in the wall cavity. All 

fresh air intake vents in both control units were found to be in the closed position. The unit at 

control A had one window partially open when these audits were performed.

Whole-house ventilation in both of the demo duplex dwelling units was provided by Panasonic’s 

Whisper Comfort spot ERV. These systems are balanced and provide exhaust and intake from 

the same terminus at both the interior and exterior (see Figure 22). Flow rate testing for the 

ERVs was not performed due to access to indoor terminus and difficulties in terminus design that 

limit ability to effectively test flow rates. The ERVs were installed in the stairwell, where safe 

access to the unit’s interior terminus was not possible with equipment available at the time of the 

audit (safe access would have required complicated rigging.) Additionally, both the interior and 

exterior terminus design make it difficult to isolate the exhaust and supply air streams from one 

another with typical flow hoods and balometers.
35

Figure 22 (Clockwise, from top left) operable fresh air wall port in living room interior, exterior, 

and infrared

The ERVs in both dwelling units are operated by ON/OFF switches located on the wall below 

the fan. The ERV in demonstration A was rarely run by the home’s occupant. The ERV in 

demonstration B was always in the “ON” position. These ERVs also contain filters that had yet 

to be cleaned or serviced by the occupants. This system was in addition to the same whole-house

exhaust ventilation strategy used in the control duplex. The fresh air intakes in these two 

dwelling units were all in the open position during the heating season (Figure 23).
36

Figure 23. ERV indoor unit (left) and outside terminus (right)

Flow rate testing of the whole-house exhaust ventilation fan in the demonstration duplex resulted 

in flow rates of 55 CFM for demonstration A and 62 CFM for demonstration B. Code-required 

minimum ventilation rate for this duplex is 45 CFM for continuous operation. With the addition 

of the ERV, combined ventilation rates for these dwelling units would be 75 CFM and 82 CFM, 

respectively, if the ERV is run on low speed. At high speed ventilation rates would be 95 and 

102 CFM, respectively. At these rates the dwelling units are likely being overventilated.

Source specific ventilation is provided for in both bathrooms of the house and in the kitchen with 

exhaust only fans. The bath fans are single-speed Panasonic fans and are controlled by twist 

timers. Flow rates for all bath fans in both units varied from 49–76 CFM. The kitchen was 

ventilated with a standard range hood and was controlled by a manual two-speed switch located 

on the unit. The kitchen fans were not tested for flow rate.

Although none of the homes at Salishan 7 are built with combustion appliances, control B was 

tested to determine the effect on house pressure with reference to the outdoors when exhaust fans 

are activated. Table 13 represents the combined house depressurization with reference to outside 

with the introduction of each exhaust ventilation system starting with the whole-house fan.

Supply air stream

Exhaust air stream
37

Table 13. Combined House Depressurization With Exhaust Fans

Control B

2.8 ACH50

House Depressurization With Reference to Outside

Fresh Air Intake Closed 

(Pascals)

Fresh Air Intake Open

(Pascals)

No Ventilation –2.0 0.0

Whole-house Fan –6.7 –5.5

+ First-Floor Bath Fan –12.2 –8.0

+ Second-Floor Bath Fan –23.1 –15.0

+ Kitchen Range Fan on HIGH –32.3 –24.2

+ Dryer –41.2 –31.3
buildingamerica.gov

DOE/GO-102013-3897 ▪ October 2013

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