Newporter Apartments: 

Deep Energy Retrofit 

Short-Term Results 

Andrew Gordon, Luke Howard, Rick Kunkle, 

Michael Lubliner, Dan Auer, and Zach Clegg

BA-PIRC

December 2012
iii

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iv

Newporter Apartments: Deep Energy Retrofit

Short-Term Results

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: 

Andrew Gordon, Luke Howard, Rick Kunkle, Michael Lubliner, Dan Auer, and Zach Clegg 

for 

BA-PIRC

1967 Clearlake Road 

Cocoa, FL 32922 

NREL Technical Monitor: Stacey Rothgeb 

Prepared under Subcontract No. KNDJ-0-40339-00 

December 2012 
v 

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vi 

Table of Contents

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

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

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

Executive Summary.................................................................................................................................... 1

Acknowledgments ...................................................................................................................................... 2

1 Introduction and Background ............................................................................................................. 3

2 Modeling Methods ................................................................................................................................ 5

2.1 Targeted Retrofit Energy Analysis Tool Analysis........................................................................... 5

2.2 Savings-to-Investment Ratio Analysis............................................................................................. 7

3 Description of Retrofit Package.......................................................................................................... 8

4 Results................................................................................................................................................. 12

4.1 Measured and Modeled Results..................................................................................................... 12

4.2 Savings-to-Investment Ratio Analysis........................................................................................... 14

4.3 Stakeholder Feedback .................................................................................................................... 19

5 Conclusions ........................................................................................................................................ 22

6 Recommendations ............................................................................................................................. 23

7 Future Research Opportunities......................................................................................................... 24

Appendix: Newporter Combustion Safety Testing Report ................................................................... 26

List of Figures

Figure 1. Newporter Apartments during retrofit ...................................................................................... 3

Figure 2. CAZ results.................................................................................................................................. 9

Figure 3. Tested CO levels for Newporter furnaces and water heaters ................................................ 9

Figure 4. Space and water heating systems pre- and post-retrofit ..................................................... 10

Figure 5. Pre- and post-retrofit energy consumption (Building A) ...................................................... 14

Figure 6. Infrared scan of wall assembly post-retrofit .......................................................................... 21

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

List of Tables

Table 1. Modeled Energy Usage Compared to Billing Data, Pre-Retrofit (Before True-Up)................ 6

Table 2. Modeled Energy Usage Compared to Billing Data, Pre-Retrofit (After True-Up)................... 6

Table 3. Summary of Energy Usage, Pre- and Post-Retrofit ................................................................ 12

Table 4. Package SIR, Calculated With Gross Energy Measure Costs ............................................... 15

Table 5. Package SIR, Calculated With Net Energy Measure Costs .................................................... 17

Table 6. Measure SIRs, Calculated With Net Energy Measure Costs .................................................. 18

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

Definitions

ACH Air changes per hour

BA Building America

CAZ Combustion appliance zone

cfm Cubic foot per minute

CO Carbon monoxide

DER Deep energy retrofit

DOE U.S. Department of Energy

EEBA Energy and Environmental Building Association

gpm Gallons per minute

h Hour

kBtu Thousand British thermal units

KCHA King County Housing Authority 

kWh Kilowatt-hour

LED Light-emitting diode

MBtu Million British thermal units

Pa Pascal

ppm Parts per million

SIR Savings-to-investment ratio

TREAT Targeted Retrofit Energy Analysis Tool

W Watt

WSU Washington State University
1 

Executive Summary

This project was designed to demonstrate a possible path to meet the goal of the U.S. Department 

of Energy’s (DOE) Building America Program to reduce home energy use by 30% (U.S. 

Department of Energy, 2012) in multifamily buildings. The research develops and documents 

market-ready energy solutions that improve efficiency, comfort, safety, and durability of 

existing, individually metered multifamily apartments in the marine climate zone of Washington 

State.

The project demonstrates cost-effective energy savings targets as well as improved comfort and 

indoor environmental quality associated with deep energy retrofits (DERs) by a large public 

housing authority as part of a larger rehabilitation effort. The project focuses on a typical 1960s 

vintage low-rise multifamily apartment community (120 units in 3 buildings). 

The DER effort at Newporter Apartments in Bellevue, Washington, is a good example of a 

nonprofit housing authority leveraging a variety of federal, state, and utility funding resources to 

implement a community-scale, system-based retrofit of envelope and mechanical systems in 

occupied units. The major retrofit measures, which were implemented in 2010, included the 

following: 

• High efficiency combination boilers, providing integrated space and water heating in 

each apartment 

• Increased wall insulation, including dense-pack cellulose, and 1 in. of Roxul exterior 

sheathing under newly renovated siding 

• New efficient windows (U-0.29) 

• Efficient lighting (predominately compact fluorescent GU24 lamps, with some lightemitting diodes) 

• Continuous whole-house mechanical exhaust ventilation (per ASHRAE 62.2 [ASHRAE 

2010]) to replace ineffective fans in the bathroom

• ENERGY STAR efficient refrigerators and dishwashers (as needed for replacement) 

• Low-flow sink and shower fixtures. 

The housing authority identified Newporter Apartments as a good DER candidate given the need 

to replace siding, windows, space and water heating equipment, ventilation systems, lighting, 

and appliances. 

This report presents the results of a post-retrofit energy analysis for the apartments using 

Targeted Retrofit Energy Analysis Tool (TREAT) analysis software (Performance Systems 

Development Consulting, 2012). The TREAT modeling results were “trued up” to pre-retrofit 

gas and electric usage. Annual whole-building measured site energy savings were 30% or 477 

MBtu. Source energy savings were estimated at 551 MBtu, based on national source energy 
2 

factors1 (Deru & Torcellini, 2007). Measured annual energy savings for gas and electricity were 

$197.54 per apartment at current utility rates. Energy retrofit measure cost data were collected to 

determine the cost effectiveness of individual measures and the retrofit packages as a whole. 

Finally, stakeholder feedback was collected and documented to identify lessons learned and help 

assess gaps and barriers.

Acknowledgments

This work is sponsored in large part by the DOE Office of Building Technology’s Building 

America Industrialized Housing Program under cooperative agreement DE-FC36-99GO10478. 

The authors thank the following persons and organizations for their contributions to this project 

and report: Mark Withrow (architect); Charlie Rogers (mechanical engineer); Jonathan Heller, 

Ecotope Inc.; Michael Stuart, Fluke Thermography; Colin Olson, The Energy Conservatory; Don 

Stevens, Panasonic USA; and Eric Martin, DOE Building America Program. 

 

1 A national source energy factor for electricity of 3.365 was used for consistency with other BA research (note that 

the source energy factor in the western United States is 2.894 because of the different electricity generation mix).
3 

1 Introduction and Background

The Washington State University (WSU) Energy Program has been providing technical 

assistance to King County Housing Authority (KCHA) staff for more than 20 years. 

In 2009, the WSU Energy Program began coordinating technical assistance efforts with KCHA 

staff involved with implementation and quality assurance of HVAC and envelope retrofit efforts 

at the Newporter Apartments in Bellevue, Washington (see Figure 1). Most of the retrofit work 

has been completed; the project is now in the post-retrofit analysis phase as part of the U.S. 

Department of Energy Building America (BA) Program’s deep energy retrofits (DERs) in marine 

climates.

Figure 1. Newporter Apartments during retrofit

The 120-unit Newporter Apartments community is composed of one-, two-, and three-bedroom 

apartments. The complex was constructed in 1968 (King County Housing Authority, 2012). 

Before the retrofits began, WSU Energy Program staff conducted several meetings and site visits 

to review the condition of the building envelopes and systems and to discuss retrofit options. The 

design process included coordination with KCHA personnel and other key stakeholders to assist 

in the assessment of measures based on available funding and rehabilitation needs. 

In 2010 and 2011, energy efficiency retrofits were implemented at Newporter Apartments. 

KCHA asset managers were first interested in replacing the leaky, unattractive, and outdated 

windows. The energy efficient retrofit measures completed to date are as follows: 

• Replacement of existing gas furnace and tank water heater systems with a combination 

ENERGY STAR® condensing boiler 

• Replacement of aluminum double-pane windows with U-0.29 vinyl windows 
4 

• Walls (2 × 4, estimated R-9) retrofitted with dense pack cellulose insulation (with 

thermography guided quality assurance), 1-in. Roxul mineral board sheathing and rain 

screen

• Replacement of incandescent lighting with ENERGY STAR compliant fluorescent and 

light-emitting diode (LED) lighting, reducing total installed wattage per unit by 

approximately 80% 

• Replacement of ineffective bathroom fans (fan flows measured below 10 cfm) with 

ASHRAE 62.2-compliant whole-house exhaust fans (ASHRAE 2010) 

• ENERGY STAR dishwasher and refrigerator (replaced as needed)

• Low-flow sink and shower fixtures. 

The modeling analysis and utility data true-up discussed in this study will capture only the 

impacts of these measures. To complete this DER, KCHA is pursuing two additional 

improvements in 2013-14, which might be the subject of future BA research: 

• Roof replacement, incorporating additional insulation and air sealing measures

• Retrofitting slab on grade to include trenched perimeter R-10 board insulation. 

KCHA funding for the Newporter energy and overall rehabilitation retrofits came from a variety 

of federal, state, and utility sources, including the following: 

• Washington State Department of Commerce Low-Income Weatherization Program 

• Puget Sound Energy, the local gas and electric utility provider 

• Building owner investments. 

The following research questions were identified in the test plan for the post-retrofit analysis for 

this phase of the project: 

1. What is the annual aggregate pre- and post-retrofit modeled energy savings of gas and 

electric usage of all units in a typical Newporter building?

2. What is the modeled savings-to-investment ratio (SIR) for packages of improvements 

with and without incentives and leveraging of resources? 

3. How do the modeled and measured energy savings compare for packages of retrofit 

measures?

4. What are the gaps, barriers, and lessons learned in this project, based on field testing, data 

analysis, and stakeholder feedback? 

5. What is an appropriate heat plant design given the physical constraints?
5 

2 Modeling Methods

2.1 Targeted Retrofit Energy Analysis Tool Analysis

In the design phase, the project collected energy efficiency measure cost information to assess 

energy savings using an energy simulation software called Targeted Retrofit Energy Analysis 

Tool) (TREAT) (Performance Systems Development Consulting, 2012). The core energy 

analysis in TREAT is performed by SUNREL, a version of SER-RES, a multinodal simulation 

tool that was originally designed by Larry Palmiter of Ecotope of Seattle. Ecotope marketed a PC 

version of the tool as Suncode. 

DOE requires low-income weatherization providers to conduct computerized energy audits with 

approved software that incorporates interactive savings with a body of measures, and (for 

multifamily projects) allows for a model true-up with billing history. After a lengthy 

investigation, the low-income weatherization providers selected TREAT several years ago.

TREAT is also required by Washington State Department of Commerce, the state funding source 

for low-income weatherization projects (Washington State Department of Commerce, 2009). 

TREAT was selected as the research analysis tool because at the time the current version of the 

Building Energy Optimization tool (BEOPT)could not be used to assess complex multifamily 

structures such as Newporter (National Energy Renewable Laboratory, 2012), (Kruis, 

Christensen, & Wilson, 2011). TREAT also offers the opportunity to true up the predicted 

energy use from the model to actual energy use. This is accomplished by adjusting assumptions 

for certain model inputs until predicted and actual energy use match.

Pre- and post-retrofit electric and gas utility data were collected from Puget Sound Energy from 

January 2007 to January 2012 for Building A (one of three buildings). The apartments are 

individually metered. Puget Sound Energy aggregated all the individual apartment data. Only 

data for the apartments (not common areas) were used in the analysis. TREAT used weather data 

from Seattle-Tacoma International Airport2 to adjust actual energy use to typical weather 

conditions. 

True-up of the TREAT model was performed using the billing data and typical meteorological 

year 3 weather data for the period analyzed (2007–2011). The purpose of true-up is to match 

model predictions with actual building energy use. For this model, true-up included reducing the 

thermostat set points and reducing the estimated infiltration rate of Building A. 

In an effort to more accurately align heating energy consumption in the model with the utility 

billing analysis, reductions in the loads were necessary. It was determined that the envelope 

inputs assumed were reasonable, so the thermostat setting was reduced from 66°F to 65.3°F. 

Researchers determined that this was a reasonable adjustment because although the units are not 

 

2 The design-phase TREAT model used Boeing Field weather data, which is closer to the location of the apartments. 

An analysis of Seattle-Tacoma International Airport weather data, however, showed that they were a closer match to 

weather conditions in Bellevue where the apartments are located. 
6 

equipped with programmable thermostats, investigators assumed that occupants used some 

degree of manual setback for nighttime and periods when the units were unoccupied. 

Air infiltration rates are commonly used as a true-up measure for buildings with no leakage rate 

test data. No available air leakage rate test data were available for the Newporter Apartments, so 

researchers used TREAT’s default leakage rate of 0.40 ACH.3 This assumption helped to true up 

the model. 

Predicted water heating consumption was adjusted to within 1% of utility measured analysis 

results. This true-up was accomplished using fixture flow rate data and equipment efficiency 

rating information from KCHA. The resulting usage was roughly 13.0 gal per occupant per day. 

This consumption rate is considered to be on the low end for multifamily housing but within 

bounds for high occupancy housing (Goldner & Price, 1994) (United States Environmental 

Protection Agency, 2011). 

Lighting fixture count and wattage per fixture data used in the model were obtained from a 

lighting audit performed by KCHA. Burn times were determined using assumptions used by the 

local electric utility, Seattle City Light (undated). Additionally, consumption data known from 

major appliances, such as refrigerators, dishwashers, and exhaust fans, were programmed into 

the model independently. Remaining loads were lumped together as a single miscellaneous load

to true up the model with the measured billing data. 

The monthly natural gas and electricity use of 36 individually metered apartment units in one 

building were analyzed. Table 1 shows the pre-retrofit model before true-up for both gas and 

electric utility use. Table 2 shows the pre-retrofit model after true-up. 

Table 1. Modeled Energy Usage Compared to Billing Data, Pre-Retrofit (Before True-Up)

Annual Consumption Model 

Predicted Billing Dataa Variance(%)

Electric Base Load (kWh) 122,714 122,714 0

Heating (Therms) 7,410 7,016 <6 

Natural Gas Baseload (Therms) 5,039 4,944 <2 

Total MBtu 1,616 1,664 <4 a Note that TREAT was used to conduct the billing analysis. Gas usage for space and water heating are 

disaggregated by the program. As input assumptions change for space and water heating, the program’s estimates of 

consumption will also change.

Table 2. Modeled Energy Usage Compared to Billing Data, Pre-Retrofit (After True-Up)

 

3 Because multifamily construction is multizone, conducting blower door tests on buildings like the Newporter 

Apartments is extremely challenging. A single blower door is insufficient to accurately determine the leakage of any 

one dwelling unit, because a portion of the tested leakage might be to adjacent apartments or common spaces, and 

the rest might leak to the outside. When this report was written, there was no clearly defined protocol for conducting 

these tests. These issues are the subject of ongoing discussions in the building science community, and were the 

subject of a BA multifamily expert meeting at the Affordable Comfort Conference in March 2012.
7 

Model Predicted Billing Data Variance (%)

Electric Base Load (kWh) 122,714 122,714 0

Heating (Therms) 6,935 6,917 <1

Natural Gas Baseload (Therms) 5,039 5,048 <1

Total MBtu 1,616 1,615 <1

2.2 Savings-to-Investment Ratio Analysis

Cost data were collected from the contractors performing the retrofit work at Newporter. These 

data were then integrated into an SIR calculation, using post-true-up numbers determined from 

the TREAT analysis. In TREAT, SIRs of greater than 1 are indicative of an economically costeffective weatherization measure or package of measures relative to investing in a market-rate 

bank CD. In this model, SIR calculations were based on state Department of Commerce 

requirements for calculating SIRs (Washington State Department of Commerce, 2009). Basic 

assumptions for this calculation include an inflation rate of 3%, a loan interest rate of 8%, a loan 

term of 30 years, and a bank rate of 6%. 

To obtain funding for weatherization measures, KCHA was required to show an SIR of greater 

than 1 for the entire package based on actual costs, including buydown from rebates and 

incentives from other sources. In addition, an SIR of greater than 1 also needed to be shown for 

individual measures within the contracted package to receive the requested funding. All cost data 

are based on gross installed costs and not incremental or pro-rated costs.

The SIR analysis does not account for the fact that in this major building renovation, some of the 

improvements were made for reasons other than energy savings and were not funded through 

weatherization grants or incentives. From the housing authority perspective, it might be 

inappropriate to assign the full cost of these measures to the energy package. In these cases, the 

researchers assume that the energy cost of these measures is zero. 
8 

3 Description of Retrofit Package

Pre-retrofit meetings between WSU Energy Program personnel and KCHA staff focused on 

energy efficiency in the design of the retrofit effort, while considering the following: 

• Occupant comfort 

• Health and safety

• Risk identification

• Risk mitigation

• Building and equipment durability

• System reliability 

• Building code compliance issues. 

KCHA hired a private energy auditor to conduct combustion appliance zone (CAZ) testing of the 

Newporter Apartments pre-retrofit. This testing identified the potential for back-drafting 

associated with the use of atmospherically vented domestic hot water (DHW) and furnaces, 

which would be exacerbated by reduced air leakage associated with window and wall retrofit 

efforts. The assessment showed that a sizable number of units failed to meet the combustion 

safety guidelines established by the Building Performance Institute (Building Performance 

Institute, 2012). The failures included the following: 

• Nine percent of DHW systems and 10% of furnaces continued to spill after 1 min. 

• Eight percent of DHW systems and 6% of furnaces had worst-case CAZ test 

depressurization below –5 Pa (see Figure 2). 

• Eleven percent of DHW systems and 17% of furnaces had unacceptable flue drafts 

(above –1.0 Pa). 

• Seventeen percent of DHW and 29% of furnaces had carbon monoxide (CO) levels in 

flue gases greater than 50 ppm (see Figure 3). 

• Gas leaks were observed in 10% of units, typically located near the gas meter/piping. 
9 

Figure 2. CAZ results 

Figure 3. Tested CO levels for Newporter furnaces and water heaters
10 

As a result of this assessment, KCHA specified a direct vent condensing boiler for each unit; 

space heating is provided by a hydronic fan coil in a new air handler with 200-W blower set at 

low speed, using the existing duct system (see Figure 4). 

Figure 4. Space and water heating systems pre- and post-retrofit 

The boiler also supplies DHW. Additionally, plumbing fixtures were replaced or augmented to 

reduce flow rates to 2.0 gpm for showerheads and 1.0 gpm for faucets. Programmable 

thermostats were installed for all heating systems. 

KCHA was able to secure funding to assist in replacing all of the existing aluminum framed 

windows. These windows were outdated and in various states of repair but more importantly 

created comfort, indoor environmental quality, and maintenance issues resulting from air 

leakage, high conductivity, and condensation. The windows were replaced with new vinyl 

framed windows with low-e insulated glass units. Installation also included air sealing measures 

now required by energy codes, which also contributed to a reduction in the building’s overall 

infiltration rate. The modeled infiltration rate for the building after window replacement was 

0.26 ACH.4

 Replacement of these windows was partially supported by a utility provider rebate 

of $6/ft2

 of window area. 

The existing wall insulation at Newporter consisted of rockwool batts that only partially filled 

the wall cavity, and was estimated at R-9. KCHA implemented the measure of leaving the 

rockwool insulation in place, densely packing the wall cavity with cellulose insulation, and 

installing 1 in. of continuous mineral wool boards to the exterior or the sheathing before an 

apartment was occupied. The estimated nominal R-value of the wall assembly after the retrofit 

was R-18. It was assumed in the TREAT model that this measure also decreased the infiltration 

rate for the building to 0.23 ACH.

Lighting upgrades implemented at Newporter included reducing the total installed lamp wattage 

per unit by an average of 955 W. This was done by replacing existing fixtures with GU24 and T8 

 

4 This is only an estimate. It is very challenging to separate out the air leakage impacts from the retrofit of any given 

component of the building (e.g., windows and walls).
11 

fixtures and 1 LED (LR6) lamp and fixture per unit. Total installed fixtures were also reduced 

from an average of 11 fixtures per unit to an average of 8 fixtures per unit. Lighting upgrade 

costs were partially paid for by utility provider incentives of $72.50/fixture.

Appliances were not replaced as a matter of course during the retrofit process, but are being 

replaced with ENERGY STAR qualified models as existing appliances reach the end of their 

service lives. 

Washington State low-income weatherization guidelines require whole-house ventilation if the 

infiltration rate drops below 0.35 ACH. Because KCHA estimated that the air sealing measures 

would lead to infiltration rates below 0.35 ACH, whole-house ventilation was added. In 

response, each unit received low-wattage (modeled at 12 W) whole-house exhaust ventilation 

systems running continuously at 59 cfm. The systems also serve as local exhaust ventilation for 

the unit’s bathroom. 
12 

4 Results

4.1 Measured and Modeled Results

Table 3 summarizes the electric and natural gas usage before and after the retrofit. The envelope 

and DHW heating measures had the most significant impact on reducing total energy 

consumption in the building analyzed; the lighting retrofit measure had the least.

Table 3. Summary of Energy Usage, Pre- and Post-Retrofit

Annual 

Consumption

Modeled Billing Analysis Variance 

From 

Predicted 

Savings 

(%) 

PreRetrofitPostRetrofit

Model 

Predicted 

Savings

PreRetrofit PostRetrofit

Total 

Savings

$ % $ %

Electric Base 

Load (kWh) 122,714 84,914 37,800 31 122,714 118,698 4,016 3 –841

Heating 

(Therms) 6,935 5,317 1,618 23 6,917 4,489 2,428 35 33

Natural Gas

Baseload

(Therms)

5,039 2,858 2,181 43 5,048 2,844 2,205 44 1 

Total MBtu 

(Site) 1,616 1,107 509 31 1,615 1,138 477 30 –7 

Total MBtu 

(Source) 2,716 1,868 849 31 2,715 2,163 552 20 –54

The majority of the savings in Building A were attributed to reductions in natural gas usage. 

Both DHW and heating loads were reduced significantly by improvements in the building 

envelope’s thermal and air barriers as well as replacement of conventional heating and DHW 

systems with a high efficiency combination space and water heating system. Natural gas

consumption was further reduced by including water-saving, low-flow plumbing fixtures. These 

savings were accomplished despite the addition of continuous whole-house ventilation (per 

Washington State low-income weatherization specifications), which in itself contributed 296.3 

MBtu in increased energy consumption from heat loss. 

The model predicted overall natural gas savings at 3,799 therms, a reduction of 32%. The 

measured reduction in natural gas consumption after 1 full year of operation was 4,633 therms or 

39%. This suggests that the predicted natural gas savings are being achieved and they are 

significant. A longer period of analysis would be needed to confirm whether actual savings are 

exceeding predicted savings. 
13 

TREAT predicted savings attributed to baseload electrical consumption from all implemented 

measures at 37,800 kWh (130 MBtu). The measured savings for 1 full year after implementation, 

though, was only 4,016 kWh (13.7 MBtu). This is a reduction in consumption of only 3% versus 

the model-predicted reduction in total electrical consumption of 31%. No clear explanation has 

been found for this modeled versus measured discrepancy, but researchers have identified 

several potential contributing factors: 

1. Occupancy rate and behavior: Given the variability of these factors, their influence on the 

discrepancy is likely high. 

2. Utility data: Because the data provided are in aggregate, it is possible that the data might 

include or exclude areas not included in the model. Determining the validity of this 

theory would require aligning meter numbers with utility data, and is beyond the ability 

of the researchers (the utility data are provided in aggregate in part to preserve 

confidentiality). 

3. Fan energy: Before the retrofit, the heating and DHW systems were naturally drafted, and 

vented independently from each other. The only measurable electrical input to either of 

them was the furnace fan, but the fan energy was not measured before the retrofit. 

Post-retrofit, the combined space/DHW system uses a 200-W furnace blower, and has 

additional loads of a coil pump and power draft fan. Run time and total electrical loads 

for these additional loads are not clear. The model produced by WSU staff assumed 

identical pre- and post-retrofit electrical loads associated with the space and water heating 

systems. A more accurate determination of the new, combined system’s input wattage 

and run times might help to shed light on the discrepancy between predicted and 

measured energy usage.

4. Characterization of lighting use: In the model, a lighting burn time of 3.3 h per fixture 

was used pre- and post-retrofit. This was based on studies referenced in the TREAT help 

menu for single-family residences. These referenced burn times varied from 2.0 to 2.47 

h/day per fixture at 1.47 and 1.25 W/ft2

, respectively (the implication is that the lower 

wattage levels result in less light, requiring the use of more fixtures). The lighting audit 

obtained from KCHA referenced an installed 1.12 W/ft2 pre-retrofit. No reference data 

for lighting burn times in multifamily housing were discovered during the writing of this 

report. It is highly likely that burn time is a significant variable. Using TREATrecommended, single-family reference data for lighting burn times would have decreased 

the electrical baseload savings discrepancy by roughly 30%. 

Although the overall energy savings realized at Newporter were significant, the overall savings 

in costs were not as significant in scale because 96% of the overall total MBtus of savings for the 

building were associated with natural gas consumption. Natural gas prices are only 43% of those 

for electricity (when compared Btu for Btu of energy). As a result, much lower cost savings are 

realized at current natural gas and electrical rates. For example, 

1 MBtu = $10.46 at current natural gas rate of 1.046/therm

1 MBtu = $24.33 at current electrical rate of $0.083/kWh. 
14 

Figure 5 graphically represents Building A monthly energy consumption under pre- and postretrofit conditions. Natural gas savings of 39% are made evident by the reduction in peak 

monthly consumption during the heating season as well as base load during the summer of 2011 

(illustrated by the red line in the graph). The 3% savings in electrical baseloads are less evident 

as illustrated by the insignificant drop to the blue line of the graph. 

Figure 5. Pre- and post-retrofit energy consumption (Building A)

4.2 Savings-to-Investment Ratio Analysis

Tables 4 and 5 list measure costs and savings for energy efficiency measures implemented at 

Newporter, and show the SIRs for the package of measures. SIRs for the implemented measures 

are shown at current utility rates and at utility rates during the period of time in which KCHA 

originally applied for funding (2009). Table 4 illustrates SIRs for gross energy measure costs 

without consideration of any rebates or incentives (gross installed costs). See the table notes for 

details. 

0.0

50.0

100.0

150.0

200.0

250.0

Jan-07

May-07

Sep-07

Jan-08

May-08

Sep-08

Jan-09

May-09

Sep-09

Jan-10

May-10

Sep-10

Jan-11

May-11

Sep-11

Jan-12

M

B

t

u

Electric Baseload

Natural Gas
15 

Table 4. Package SIR, Calculated With Gross Energy Measure Costs

Model-Predicted Contracted Package SIR (Gross Costs)

Measure

Cost Savings Payback Implementation

Life SIR of 

Packagea

SIR of 

Packageb

$ MBtu $ Years Years

DHW 64,084 86.8 908 70.6 15

0.54 0.60 

Heating System 64,084 103.9 1,087 58.9 15

Wall Insulation 43,613 98.8 1,034 42.2 40

Air Sealingc 0 172 1,799 N/A 20

Lighting 27,075 50.6 2,490 10.9 15

Window Replacementd 113,835 259.2 2,712 42 30

Total for Package 312,691 771.3 10,029 31.2 N/A

a SIR was calculated at 2012 utility rates of $1.046/therm and $0.083/kWh. b SIR was calculated at 2009 utility rates of $1.22/therm and $0.076/kWh. c This cost is representative of the measure being an incidental benefit of other measures. The modeled total infiltration rate dropped from an estimated 

0.40 ACH to 0.16 ACH (Auer, Watkinson, & Doran, 2012). d This cost reflects a $6/ft2 gas and electric utility incentive. 
16 

The SIR calculation is based on a 3% inflation rate, an 8% interest rate, a 30-year loan term, and 

a 6% bank rate. As seen in Table 4, the weatherization measures installed at Newporter would 

not be considered cost effective, using the above financial factors and gross installed costs of 

measures.

There is a compelling argument, however, for reducing installed costs of measures, considering 

contributions from other funding sources (in this case the gas and electric utility). 

In addition, there is a way to consider avoided costs associated with health and safety 

improvements. In Newporter, the replacement of naturally drafted heating and DHW systems is

clearly justified from a health and safety standpoint, and costs related to this replacement should 

be backed out from the SIR calculation. 

Table 5 presents TREAT’s SIR calculation with these installed costs modified by these 

considerations, and shows a package SIR greater than 1.0. 
17 

Table 5. Package SIR, Calculated With Net Energy Measure Costs

Model-Predicted Contracted Package SIR (Net Costs)

Measure

Cost Savings Payback Implementation

Life SIR of 

Packagea

SIR of 

Packageb

$ MBtu $ Years Years

DHWc 0 86.8 908 N/A 15

1.29 1.43 

Heating Systemc 0 103.9 1,087 N/A 15

Wall Insulation 43,613 98.8 1,034 42.2 40

Air Sealingd 0 172 1,799 N/A 20

Lightinge 8,950 50.6 2,490 3.6 15

Window Replacementf 79,265 259.2 2,712 29.2 30

Total for Package 131,828 771.3 10,029 14.1 N/A

a SIR was calculated at 2012 utility rates of $1.046/therm and $0.083/kWh. b SIR was calculated at 2009 utility rates of $1.22/therm and $0.076/kWh. c This measure was deemed a health and safety concern because of combustion gas spillage and was not required to meet an SIR of 1.0 or greater. d This cost is representative of the measure being an incidental benefit of other measures. The modeled total infiltration rate dropped from an estimated 

0.40 ACH to 0.16 ACH (Auer, Watkinson, & Doran, 2012). e This cost reflects a gas and electric utility incentive of $72.50/fixture. f This cost reflects a $6/ft2 gas and electric utility incentive. 
18 

Table 6 shows the SIR calculations for each measure run independently, without the interactive effects of other measures in the 

package. 

Table 6. Measure SIRs, Calculated With Net Energy Measure Costs

Model-Predicted Contracted Individual Measure SIR (Net Costs)

Measure

Cost Savings Payback Implementation

Life SIR of 

Measurea

SIR of 

Measureb

$ MBtu $ Years Years

DHWc 0 78.1 817 N/A 15 N/Ad N/Ad

Heating Systemc 0 115.6 1,209 N/A 15 N/Ad N/Ad

Wall Insulatione 43,613 213.2 2,230 19.6 40 1.0 1.17 

Air Sealingf 0 190.9 1,997 N/A 20 N/Ag N/Ag

Lightingh 8,950 40.4 2,384 3.8 15 3.2 2.57 

Window Replacementi 79,265 370.2 3,872 20.5 30 0.98 1.15 a The SIR was calculated at 2012 utility rates of $1.046/therm and $0.083/kWh.

b The SIR was calculated at 2009 utility rates of $1.22/therm and $0.076/kWh. c This measure was deemed a health and safety concern because of combustion gas spillage and was not required to meet an SIR of 1.0 or greater.

d The SIR calculation was not computed for this measure because the funding source did not require it (because it was a health and safety measure). e These values include energy savings related to incidental air sealing. The values are based on WSU’s pre-retrofit estimated infiltration rate of 0.40 

ACH and KCHA’s post-retrofit estimated infiltration rate of 0.268 ACH. f This cost is representative of measure being an incidental benefit of other measures. The modeled total infiltration rate dropped from an estimated 0.40

ACH to 0.16 ACH(Auer, Watkinson, & Doran, 2012) g The SIR calculation was not computed for this measure because there was no cost. The measure was an incidental benefit of insulation and window 

replacement measures.

h This cost reflects an incentive from the gas and electric utility of $72.50/fixture. i

This cost reflects a $6/ft2 gas and electric utility incentive and includes energy savings related to incidental air sealing. These values are based on

WSU’s pre-retrofit estimated infiltration rate of 0.40 ACH and KCHA’s post-retrofit estimated infiltration rate of 0.292 ACH.
19 

As the results indicate, high-cost measures are challenged to meet the SIR criteria. The measure 

SIR analysis does not take into account the “lost opportunity” costs of not completing these 

retrofits. A prime example is the insulation added to the walls. When KCHA retrofitted the 

windows, the planners could have chosen not to add the cellulose insulation to the cavity or add 

the Roxul to the exterior. They chose to do so at a time when the siding had been removed for 

the window replacement, providing maximum value for the retrofit. If they had not done so then, 

adding insulation at another time would have been significantly more costly. 

Several other issues in determining costs for retrofits in projects like Newporter remain:

• Leaving aside the fact that health and safety measures do not require calculation of an

SIR, how do we best determine avoided health impacts and their associated costs for 

replacement of atmospherically vented space and water heating systems?

• What is the appropriate measure cost for windows that are not functioning well and need 

to be replaced?

• What is the measure cost for replacing appliances at the end of their useful lives? 

• What is the measure cost of replacing lighting fixtures that have faulty wiring?

• How did the overall retrofit effort increase the useful life of the project and what level of 

savings was achieved by not having to build new housing? 

4.3 Stakeholder Feedback

Post-retrofit, WSU Energy Program personnel interviewed KCHA staff that managed the project

and the Newporter apartments on site (Auer, Watkinson, & Doran, 2012). KCHA staff identified 

the following lessons learned from the Newporter DER: 

• The apartments were built in 1968 and KCHA recognized the need for renovation work. 

The original impetus for the retrofit, to replace the existing, leaky, and unattractive 

windows, led to concerns about using existing atmospherically vented space and water 

heating equipment. KCHA staff are trained and experienced with issues of combustion 

safety. Working with WSU Energy Program staff, combustion safety issues were 

identified and it was quickly determined that the retrofit effort would have to include 

considerations of space and water heating systems as well as envelope improvements.

• Replacement of the space and water heating systems created challenges: 

o The combustion safety assessment led KCHA to pursue direct vent equipment to 

replace the existing furnace and water heater.

o No water heater storage tanks could be found to fit in the utility closet (7 ft × 3 ft) 

and leave room for a separate space heating system, leading to the choice of a 

boiler, combining space and water heat. 

o Deciding to use the condensing boiler for space and water heat also had 

challenges. Initially, the smallest unit KCHA staff found was listed with a 

capacity of 200 kBtu/h. Not only was this twice as much as was needed, but the 

gas piping at Newporter was sized for a much smaller load (existing furnace 
20 

capacity of 60 kBtu/h). The solution selected had its capacity adjusted (by the 

manufacturer) from 200 to 100 kBtu/h. 

o The use of the boilers (on demand) also limited hot water flow to 3–4 gpm. Even 

with the addition of low-flow water appliances, Newporter residents have had to 

adjust their lifestyle habits accordingly: “They don’t shower and run the 

dishwasher at the same time.” If KCHA chooses to retrofit the gas piping in the 

future, the system capacity can be readjusted, which could allow for more hot 

water flow.

o The use of a direct vented boiler meant that the combustion air needed to be 

supplied from and vented to the outside. KCHA staff decided to use the existing 

8-in. metal sleeves to run the combustion supply and exhaust. 

• The window retrofit was quick and easy, and coordinated well with the installation of the 

Roxul sheathing. 

o The Roxul did not provide structural integrity as backer for the window flange 

and fastening. A strip of extruded polystyrene was installed around the window, 

and the Roxul was butted up to that. 

o Doing the windows with the wall retrofit saved costs and resulted in a better 

thermal package.

• The wall retrofit was considered very successful by KCHA staff, though it required a fair 

amount of supervision and explanation to contractors. 

o Infrared thermography proved to be very useful in identifying insulation 

anomalies (see Figure 6). 

o KCHA had a lot of experience with the use of dense pack cellulose, though this 

was the first time that one of its projects used an exterior sheathing. Because the

re-siding was part of the window replacement, it was an ideal time to install the 

sheathing. The integrated package created synergies. In addition, the Newporter 

project was a good candidate for this approach because it did not have a lot of 

angles or alcoves. 

o The sheathing eliminates thermal bridging. This eliminates cold spots where 

water can condense and lead to mold growth. 

o KCHA staff highlighted the need to coordinate among multiple subcontractors, 

some of which do not consider weatherization a priority.

o In the end, the major question for KCHA staff is not whether to use the exterior 

sheathing in future projects, but how much: “The biggest question is whether we 

do 1 in., 11⁄2 in., or 2 in.”

• The existing exhaust fans did not meet the low-income weatherization program 

specifications, so they needed to be replaced. 

o The existing fans were chain-switch operated; additional wiring was necessary to

convert them to wall-switch control. 
21 

o Because the existing fan duct runs were long, there was some concern that the 

new fans would be challenged to meet the flow requirements, but under testing, 

they met requirements. 

• All lighting was retrofitted to an ENERGY STAR alternative, primarily GU24 compact 

fluorescents, though some LED lighting was also installed. 

o The existing incandescent fixtures were rated for 75-W lamps, but in many cases, 

residents had installed 100-W lamps, burning the insulation off the wiring. In 

addition to fixture replacement, contractors spent a fair amount of time reinsulating the wires. This work was included in the lighting contractor’s unit 

costs.

Before the retrofit, KCHA staff estimated that more than 50% of the occupants had complaints 

about comfort and drafts. Following the retrofits, KCHA staff said that the feedback was 

overwhelmingly positive (no more cold and draft complaints), with a few complaints about 

inadequate hot water supply. 

KCHA staff are also very satisfied with the project. Highlights include the use of the boiler 

combination water and space heating, and the use of Roxul fiber board. 

Figure 6. Infrared scan of wall assembly post-retrofit 
22 

5 Conclusions

This project raised confidence in energy savings model predictions via utility data true-up. 

Anticipated gas savings, modeled and trued up with utility data, met expectations; savings 

associated with electric usage did not. 

The model predicted electrical baseload energy savings of 37,800 kWh/yr for the building 

analyzed. The measured electricity savings were 4,016 kWh/yr; only 10.6% of the model’s 

prediction. This discrepancy cannot be explained without further investigation into such factors 

as the quality of usage data received from the utility, and whether the billing includes shared 

areas, occupancy behavior, and baseline assumptions. The model predicted natural gas savings of 

3,799 therms/yr. This compared to the measured energy savings of 4,633 therms/yr, or $4,846 at 

$1.046/therm.

Overall, the total measured savings for Building A post-retrofit is 477 MBtu/yr or $5,179 

(approximately $143.86 per apartment annual savings) at current gas and electric utility rates. 

Source energy savings were 552 MBtu/yr. Feedback from KCHA quality assurance staff 

suggests that the use of infrared thermography was especially useful for assessing dense pack 

wall insulation. 

The research effort seeks to maximize the cost effectiveness of each measure and strategy by 

employing a systems engineering approach to DERs, implemented during substantial 

rehabilitation of typically low-income occupied rental units. At the same time, the research has 

identified low SIRs (less than 1) for the package, if all of the costs associated with the measures 

are to be subsidized by energy savings. For the project to have achieved an SIR of 1, the 

incremental cost of the project would need to be reduced from $312,928 for the building 

analyzed here, to approximately $132,065. When incentives are included, however, the SIR 

increases to greater than 1 in most cases.

Note that other, nonenergy savings benefits, although not included in an SIR calculation, are 

associated with these retrofits, including the following: 

• Health and safety, including combustion safety, and indoor air quality 

• Deferred maintenance associated with appropriately retired space and water heating 

equipment, appliances, and lighting, as well as the outdated windows 

• Occupant comfort; complaints were significantly reduced

• Durability improvement; Roxul sheathing and rain screen reduced condensation in the 

wall and protected against bulk-driven moisture. Adding a whole-house ventilation 

system and improved windows will also reduce condensation. 

The successful demonstration of this effort is scalable to other communities owned by KCHA 

and other public housing authorities in Washington State in need of retrofits to the envelope and 

systems. 

The research can help inform efforts in improving BA and state weatherization guidelines in 

multifamily projects throughout the Northwest region.
23 

6 Recommendations

The timing of a DER is crucial. In this project, KCHA was able to integrate the energy efficiency 

measures as part of a substantial renovation process. Coordination of these retrofit efforts, 

involving occupied units, was successful, though more challenging. This project also 

demonstrated the value of combining housing authority renovation and energy improvement 

funding. 

For combined low-income weatherization and renovation projects, SIR should not be the only 

consideration. Other considerations must be factored in, including comfort, health, and safety. In 

addition, this approach helps to avoid future maintenance crises and extends the useful life of the 

project by avoiding the high cost of new construction. 

An upfront investment in the project design phase, incorporating a systems approach, produces 

synergies that improve performance and reduce lost opportunities typical of one-at-a-time 

measure approaches.

Investing time and effort into on-site project management, quality assurance, and training of 

contractors significantly improved installation of energy efficiency measures. Specific areas 

include the following: 

• Pre-retrofit characterization, including combustion safety testing, exhaust fan flow rates, 

and occupant and other stakeholder feedback associated with comfort and indoor 

environmental quality 

• Technical support and training of staff to assist in the verification of dense-pack wall 

insulation, using thermography during the installation process 

• Measurement and commissioning of HVAC equipment after installation.

Verification of modeled energy use with actual pre- and post-retrofit billing data is critical to 

assessing the value of the overall package and individual measures. This can yield valuable 

feedback for future DERs.
24 

7 Future Research Opportunities

Additional slab and roof insulation retrofits are scheduled for 2013–2014. Evaluation and 

implementation of these retrofits are additional opportunities for continued BA research.

Further investigations into the discrepancy between the modeled and measured electrical 

baseload savings are warranted. Identifying the contribution of HVAC fan and pump energy, 

lighting use characterization, and how the utility billing data were provided to researchers may 

reduce this discrepancy. 

Occupied units complicate the logistics for implementing DERs. KCHA has other unoccupied 

communities slated for gut rehab, where the potential for additional BA support for even deeper 

energy retrofits could exist. 

BA research into the development of climate-specific DER packages might provide prescriptive 

alternatives where resources for the implementation of modeling and billing analysis are limited. 
25 

References

Auer, D., Watkinson, H., & Doran, N. (2012, January 31). Phone Interview. (K. Rick, & A. 

Gordon, Interviewers) 

Building Performance Institute. (2012). COMBUSTION SAFETY TEST PROCEDURE .

Retrieved from Building Performance Institute: 

http://bpi.org/files/pdf/CombustionSafetyTestProcedure-GoldSheet.pdf 

Deru, M., & Torcellini, P. (2007). Source Energy and Emission Factors for Energy Use in 

Buildings. Golden: National Renewable Energy Laboratory. 

Goldner, F. S., & Price, D. C. (1994). Domestic Hot Water Loads, System Sizing and Selection 

for Multifamily Buildings. ACEEE Summer Study. Panel 2, Paper 12. Washington: 

American Council for an Energy Efficient Economy. 

King County Housing Authority. (2012). Newporter Private Housing. Retrieved January 27, 

2012, from King County Housing Authority: 

http://www.kcha.org/lookingforhousing/propertyfactsheet.aspx?pfid=152 

Kruis, N., Christensen, C., & Wilson, E. (2011, August). (E. Salzberg, Interviewer) 

National Energy Renewable Laboratory. (2012). BEOPT. Retrieved from National Energy 

Renewable Laboratory: http://beopt.nrel.gov/

Performance Systems Development Consulting. (2012). TREAT. Retrieved from Performance 

Systems Development: http://www.psdconsulting.com/software/treat 

Seattle City Light. (n.d.). Residential Conservation - Compact Flourescent Bulbs. Retrieved May 

22, 2012, from Seattle City Light: 

http://www.seattle.gov/light/conserve/resident/cv5_lw2.htm

U.S. Department of Energy. (2012). Program Goals. Retrieved from Building America: 

http://www1.eere.energy.gov/buildings/building_america/program_goals.html 

United States Environmental Protection Agency. (2011, June). Energy Star Multifamily High 

Rise Program Simulation Guidelines. Retrieved May 22, 2012, from Energy Star: 

http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/mfhr/ENERGY_S

TAR_MFHR_Simulation_Guidelines_V1.0.pdf 

Washington State Department of Commerce. (2009). Weatherization Manual For Managing the 

Low-Income Weatherization Program.
26 

Appendix: Newporter Combustion Safety Testing Report 

Description of Issues and Resolutions: 

Combustion Appliance Zone (CAZ) tests in graphs below suggest: 1) appliance flue 

back drafting potential, 2) high carbon monoxide concentrations in flue gas, and 3) 

natural gas leaks associated with the individual apartment mechanical room gas piping 

and gas meters. Proposed deep energy retrofit of building envelope, including; dense 

pack foam walls, exterior house wrap and 1” insulated sheathing, are likely to increase 

the tightness of the apartments, and further increase flue back drafting potential, and 

higher concentrations of indoor air pollutants. To avoid back drafting problems and to 

further reduce space and water heating energy usage, a new sealed combustion 

combination space heater and demand DHW boiler was installed in each apartment. 

The smallest available condensing boiler for this product line available was 200KBTU, 

which is twice as large as required for the apartment hot water fixture demand and 

space heat demand at design temperature, and there were concerns that the existing 

gas piping may not be large enough. To address these concerns the boiler 

manufacturer de-rating the equipment to 100kbtu and re-listing it for code approval. The 

de-rated boiler was able to operate using the existing gas pipe diameter, originally sized 

for a 60kbtu furnace and standard DHW storage water heater. 
27 

Another concern was the minor gas leaks found in 10% of mechanical rooms during the 

pre-retrofit CAZ testing of the mechanical room. Envelope tightening measures and 

retrofitting of sealed combustion equipment reduce infiltration rates, leading to 

potentially higher incidents of gas leaks. To address these IAQ issues, ASHRAE 62.2 

compliant low-sone, whole house exhaust only ventilation systems were designed and 

installed to provide acceptable ventilation rates in each apartment. The ventilation 

system runs continuously on low speed without occupant control, and controls allow 

occupant to increase flow rates for bathroom spot ventilation. 

Example Description of Potential Error(s): 

 

Each apartment had a mechanical room as shown in the photo, with atmospherically 

vented natural gas water heaters and furnaces, individual utility gas meters and 1” 

supply gas lines. The contractor proposed to install a variety of retrofit wall measures 

that will tighten up the building envelope, including energy efficient “tighter” windows, 

and a combination of the following wall measures: 1) dense pack walls 2) continuous 

weather resistant membrane (WRP) 3) RoxUL insulated sheathing 4) new siding 5) wall 

penetrations sealed and 6) installation of continuously operated whole house/bathroom 

exhaust fans. Prior to retrofit, a contractor conducted a series of combustion safety tests 

of gas piping, furnace flue and DHW flue, in each of the 118 apartment units. The 

results were as follows: 

• 9% of DHW and 10% of furnaces had combustion flue spillage

• 8% of DHW and 6% of furnaces had worse case CAZ test depressurization below -5 PA

• 11% of DHW and 17% of furnaces had flue drafts above -1.0 PA

• 17% of DHW and 29% of furnaces had CO levels in flues gas greater than 50 PPM

• Observation of gas leaks 10% of units, typically located near the gas meter/piping.
28 

Description of Implementation Errors: 

There would have been greater potential combustion safety and indoor air quality 

issues, had the BA team not addressed CAZ testing issues by: 1) replacing low 

13 | Newporter Apartments eere.energy.gov

Combustion Safety Tests (continued)

BPI Worst Case Depressurization 

Limit for Commonly Vented Furnace 

& Water Heater 

14 | Newporter Apartments eere.energy.gov

0

50

100

150

200

250

300

350

400

0 50 100 150

Flue Gas CO PPM

Unit

Furnaces

1 Unit @2000+ 

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120

Flue Gas CO PPM

Units

Hot Water Heaters

5 Unit @2000+

BPI Standard < 25 PPM
29 

efficiency atmospherically vented mechanical equipment with correctly sized high 

efficiency sealed combustion and 2) installing ASHRAE 62.2 compliant ventilation.

 

Risks: 

• Considerable potential health and safety risks from increased occupant exposure to combustion 

flue dangerous byproducts such as carbon monoxide, etc. from back drafting. 

• Considerable potential health and safety risks from reduced mechanical room 

ventilation/infiltration may increase the concentration of natural gas in the mechanical room 

resulting from any future leaks of the gas piping. 

Required Corrections: 

• Installation of sealed combustion DHW and furnace

• Installation of ASHRAE 62.2 compliant ventilation

• Installation of CO alarms in mechanical rooms 

• Identification of any future natural gas piping leaks and occupant IAQ related issues

Applicable or Potential Guideline Documents: 

• BPI combustion safety protocols; flue spillage, CAZ worst case, flue draft, gas leakage 

• Manufacturer manual to ensure furnace heat rise within specifications 

• UMC and manufactured gas piping sizing manuals and codes for demand boilers, requiring high 

gas flow rates
 

DOE/GO-102012-3760 ▪ December 2012

Printed with a renewable-source ink on paper containing at 

least 50% wastepaper, including 10% post-consumer waste.