Northwest Energy Efficient 

Manufactured Housing Program 

Specification Development 

Tom Hewes and Brady Peeks

BA-PIRC

February 2013
ii

NOTICE

This report was prepared as an account of work sponsored by an agency of the 

United States government. Neither the United States government nor any agency 

thereof, nor any of their employees, subcontractors, or affiliated partners makes any 

warranty, express or implied, or assumes any legal liability or responsibility for the 

accuracy, completeness, or usefulness of any information, apparatus, product, or 

process disclosed, or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade 

name, trademark, manufacturer, or otherwise does not necessarily constitute or imply 

its endorsement, recommendation, or favoring by the United States government or 

any agency thereof. The views and opinions of authors expressed herein do not 

necessarily state or reflect those of the United States government or any agency 

thereof.

Available electronically at http://www.osti.gov/bridge

Available for a processing fee to U.S. Department of Energy

and its contractors, in paper, from:

U.S. Department of Energy

Office of Scientific and Technical Information

P.O. Box 62

Oak Ridge, TN 37831-0062

phone: 865.576.8401

fax: 865.576.5728

email: mailto:reports@adonis.osti.gov

Available for sale to the public, in paper, from:

U.S. Department of Commerce

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

phone: 800.553.6847

fax: 703.605.6900

email: orders@ntis.fedworld.gov

online ordering: http://www.ntis.gov/ordering.htm

Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste
iii

Northwest Energy Efficient Manufactured Housing Program 

Specification Development

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: 

Tom Hewes and Brady Peeks

Northwest Energy Works of the 

Building America Partnership for Improved Residential Construction 

37368 Blue Heron Rd. 

Corvallis, OR 97330 

NREL Technical Monitor: Stacey Rothgeb 

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

February 2013 
iv

[This page left blank]
v 

Contents

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

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

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

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

Acknowledgments..............................................................................................................................viii

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

2 Specifications for the High Performance Manufactured Home ..................................... 4

3 Developing the Measures ............................................................................................................ 5

3.1 Improved Floor Insulation Effectiveness ......................................................................................5

3.2 Rigid Insulation on the Exterior of the Wall Structure over the Sheathing ......................5

3.3 Triple Glazed Windows........................................................................................................................5

3.4 Increased Ceiling Thermal Performance ......................................................................................5

3.5 Overall Uo Reduction............................................................................................................................5

3.6 HVAC System............................................................................................................................................6

3.7 Domestic Hot Water System...............................................................................................................6

3.8 Lighting......................................................................................................................................................7

3.9 Appliances ................................................................................................................................................8

3.10 Wholesale Price to the Retailer......................................................................................................8

3.11 Modeling.................................................................................................................................................9

3.12 Energy Use Calculations................................................................................................................. 11

3.13 Savings ................................................................................................................................................. 13

4 Next Steps ........................................................................................................................................14

5 Discussion.......................................................................................................................................15

6 Conclusions ....................................................................................................................................17

Bibliography .........................................................................................................................................18

Appendix: Cost Assessment for Manufactured Homes ..........................................................20

High R-Value Walls........................................................................................................................................ 20

High R-Value Roofs........................................................................................................................................ 21

High R-Value Floors ...................................................................................................................................... 22

High Efficiency Windows............................................................................................................................. 23

HVAC Equipment and System Technologies ........................................................................................ 23

Domestic Hot Water Technologies .......................................................................................................... 24

Lighting Technologies .................................................................................................................................. 24

Solar Technologies ........................................................................................................................................ 25
vi 

List of Figures

Figure 1. HPMH Annual Energy Savings (Prototype Weighted)........................................................... 12

Figure 2. Manufactured Home Total Energy Use (Prototype Weighted) ............................................. 13

Figure 3. House Energy Use by Category ......................................................................................... 12

Unless otherwise noted, all figures were created by Northwest Energy Works. 

List of Tables

Table 1. Detailed HPMH Specifications..................................................................................................... 4

Table 2. Measure Cost by Category .......................................................................................................... 8

Table 3. SEEM DHP Performance Calibration Results.......................................................................... 10

Table 4. Energy Use, Savings, and Benefit/Cost Ratio ......................................................................... 13

Unless otherwise noted, all tables were created by Northwest Energy Works. 
vii 

Definitions

ACH Air changes per hour

BPA Bonneville Power Administration

CFL Compact fluorescent lamp

cfm50 cubic feet per minute at 50 Pascals

DAPIA Design Approval Primary Inspection Agency

DHP Ductless heat pump

DHW Domestic hot water

EF Energy factor

ft2 Square foot

gpd Gallons per day

gpm Gallons per minute

HPMH High performance manufactured home

HPWH Heat pump water heater

kW Kilowatt

kWh Kilowatt-hours

LED Light-emitting diode

LPD Lighting power density

MAP Manufactured Housing Acquisition Program

MH Manufactured housing

NEEA Northwest Energy Efficiency Alliance

NEEM Northwest Energy Efficiency Manufactured Housing 

Program 

NEW Northwest Energy Works

NPCC Northwest Power Conservation Council 

O&M Operations and maintenance

PNNL Pacific Northwest National Laboratory

RTF Regional Technical Forum

SEEM Seasonal Energy and Enthalpy Model

Uo U overall

W Watt

WSU Washington State University Extension Energy Program
viii

Executive Summary

The Building America Partnership for Improved Residential Construction, the Bonneville Power 

Administration (BPA), and Northwest Energy Works, the current Northwest Energy Efficient 

Manufactured Housing Program (NEEM) administrator, collaborated to conduct research on new 

specifications that would improve on the energy requirements of a NEEM home. The team also 

evaluated energy savings that would result from the new specifications. In its role as 

administrator, NEEM administers the technical specs, performs research and engineering 

analysis, implements ongoing construction quality management procedures, and maintains a 

central database with home tracking. 

For this project, researchers asked three questions: 

1. Which measures could be built into a NEEM home to achieve a 50% reduction in space 

conditioning, lighting, and water heating energy use, compared with usage levels 

resulting from the current specifications? 

2. What are the challenges in building a high performance manufactured home (HPMH)? 

3. What are the modeled energy savings of an HPMH? 

This research identified and developed combinations of cost-effective high performance building 

assemblies and mechanical systems that can be readily deployed in the manufacturing setting. 

Key technologies explored and implemented included ductless heat pumps (DHPs) with zonal 

electric resistance heating in secondary zones, heat pump water heaters, high performance 

windows, new wall assemblies with reduced thermal bridging (e.g., exterior rigid foam 

sheathing), and new roofline designs that allow for more insulation. 

Acknowledgments

We want to thank Eric Martin and the staff of the Florida Solar Energy Center Building America 

Partnership for Improved Residential Construction and Subrato Chandra and Graham Parker at 

the Pacific Northwest National Laboratory, in addition to all the other project partners. The 

region’s manufactured housing industry is a key partner in this project. Northwest Energy Works 

worked with many of the factories’ engineering, production, and quality management personnel 

to develop and test each measure proposed for inclusion in the new HPMH specifications. Plant 

staff at Fleetwood Homes of Oregon and Kit Homebuilders West deserve special thanks for their 

contributions. Industry partners included the following: 

Champion Home Builders, Weiser, Idaho 

Fleetwood Homes of Oregon, Woodburn, Oregon 

Fleetwood Homes of Idaho, Nampa, Idaho 

Golden West Homes, Albany, Oregon 

Kit Homebuilders West, Caldwell, Idaho 

Marlette Homes, Hermiston, Oregon 

Nashua Homes of Idaho, Inc., Boise, Idaho 

Palm Harbor Homes, Millersburg, Oregon 
ix

Skyline Corporation, McMinnville, Oregon 

Valley Manufactured Housing, Sunnyside, Washington. 

Special thanks go to the BPA and other regional utility partners in this project. BPA is an active 

partner in developing the new specifications and helping to bring other regional utilities to the 

table with the intent to develop a regional HPMH program. If and when the HPMH package 

begins to be included in new manufactured home construction, utility incentive funds will 

leverage this project’s efforts by bolstering consumer demand (or lowering manufacturer costs) 

for higher efficiency homes. 

Thanks to Ecotope Engineering’s David Baylon and Bob Davis, who provided engineering, 

technical support, and measure development to the project. Ben Larson’s energy modeling work 

and presentation to the Regional Technical Forum were absolutely first rate. 

Thanks to Jim Russell of RC Creative Group and home design company Ideabox, LLC. Russell’s 

knowledge of and experience with designing and building HUD-code homes allowed him to 

contribute important market planning for a HPMH program to the project. Ideabox sold 8 of its 

last 10 homes with DHPs and agreed to prototype a home with R-5 foam sheathing. 

The Heat Pump Store specializes in DHPs, and its staff trained the factory personnel to install 

DHP zonal heating and cooling systems. Jeff Pratt, president of The Heat Pump Store, and his 

business partners John and Sara Marisconi own and operate Ductless Supply in Portland. 

Ductless Supply offered wholesale prices to all the manufactured home plants in the Pacific 

Northwest. In addition they trained plant personnel to factory install the DHP systems. The Heat 

Pump Store teamed up with Northwest Energy Works to train installers to size and install the 

hybrid DHP zonal electric heating systems. 
1 

1 Introduction

Based on the most recent (2008) evaluation field survey and billing analysis (Baylon, et al. 2009) 

of the Northwest Energy Efficiency Manufactured Housing Program (NEEM) homes, the annual 

potential savings percentage for a high performance manufactured home (HPMH) over a typical 

baseline home produced in the Pacific Northwest region (Idaho, Montana, Oregon, and 

Washington) would be 50%. This equates to about 8,000 to 10,000 kWh for each home produced 

and sited. Northwest Energy Works (NEW) worked with the manufactured housing (MH)

industry, the involved in-plant primary inspection agency, the appropriate design approval 

primary inspection agency (DAPIA), retailers, industry associations, the Building America

Program, the Pacific Northwest National Laboratory (PNNL), the Northwest Power 

Conservation Council (NPCC), and utilities to develop the HPMH specifications. 

Achieving this level of energy efficiency improvement requires several significant changes to 

current construction methods and mechanical system designs. This research involved technical 

support to manufacturers to help them with developing measure costs and construction processes 

and prototyping new systems and building assemblies. The measures developed for the NEEM

HPMH specification have appreciable applicability to existing manufactured homes, especially 

measures that affect the home’s structure. This effort involved engineering approvals for the new 

construction methods. Construction methods developed through this project might well be 

readily adopted as best practices in new and retrofit work. 

This research identified and developed combinations of cost-effective high performance building 

assemblies and mechanical systems. These systems can be readily deployed in the manufacturing 

setting to reduce energy used for space conditioning, water heating, and lighting. 

The results of energy modeling of the HPMH were presented to the NPCC’s Regional Technical 

Forum (RTF), which accepted the specifications and established deemed energy savings values

based on the energy modeling results. Pacific Northwest private and public utilities use the 

RTF’s approved deemed savings to develop incentives for programs like the HPMH. 

Key technologies included in the research at NEEM participating plants and included in the 

HPMH follow: 

• Ductless heat pumps (DHPs) with zonal heating in secondary zones: The hybrid zonal 

system eliminates the existing electric forced-air furnace and duct system from the home 

altogether. A single ductless mini-split heat pump connected to one or two indoor heads 

is sized to meet the majority of the home’s heating load, and electric wall or baseboard 

heaters are located throughout the house so that each room has an independently 

controlled supplemental source of heat. The DHP differs from conventional unitary heat 

pump equipment in that a DHP can be reliably installed and commissioned on the 

production line, ready for transport to the homebuyer’s site. This eliminates the need for

aftermarket heat pump installation. With technical support from NEW, plant workers will 

design and install supplemental zonal heating systems appropriate for all Pacific 

Northwest climate zones. 
2 

• Heat pump water heaters (HPWHs): The HPMH specification will require that HPWH 

equipment meet Tier 2 of the Northwest Energy Efficiency Alliance’s (NEEA’s) 

Northern Climate Heat Pump Water Heater specification, plus have the ability to fully 

duct the process air. The project team wants to be sure to achieve three key elements: 

exhaust air ducting, quiet operation, and defrost capability to permit operation in colder 

temperatures. For optimal operation in MH applications, the HPWH would be designed 

to draw air from the home’s crawlspace, transfer its heat into the domestic hot water 

(DHW) tank, and then exhaust the resultant cool air via an exhaust duct to the outside. 

Appropriate products with sufficient availability are only now beginning to arrive in the 

market.

• High performance windows (R-5): Triple pane vinyl windows are available in the Pacific 

Northwest. The company that currently supplies the majority of the region’s

manufactured housing window market is not building R-5 windows, but two window 

manufacturers supplying a minority of the region’s manufactured housing industry are 

producing R-5 windows. 

• Improved wall assembly: A new wall assembly with exterior rigid foam sheathing added 

to reduce thermal bridging can be implemented with modest impact on plant production 

processes. The Kit Homebuilders plant in Idaho is prepared to prototype this wall 

assembly. NEW will assist with any needed DAPIA engineering approvals before the 

prototype home is built. 

• Improved attic thermal performance: New roof insulation strategies can achieve a 

marginal improvement to current practice without changing the roof trusses being used. 

Switching to trusses with greater heel heights could result in taller home sections and

cause transportation issues. The primary improvement that appears to be feasible for 

implementation involves increasing insulation levels in the eave areas and extending 

inward up to 4 ft, resulting in an attic depth sufficient for blown-in insulation to achieve 

acceptable insulation levels. Compressing high-density R-30 fiberglass batts under 

baffles and dense packing loose fill cellulose insulation under baffles could prove to be 

low-cost, easily implemented strategies that offer higher R-values per inch of depth than 

today’s standard practice of using loose fill insulation exclusively. One plant has 

expressed interest in exploring the use of spray foam for its attic assemblies. 

1.1 Background

In 1992 the Bonneville Power Administration (BPA) and the MH industry agreed to a single 

energy efficiency standard that would apply to all electrically heated homes sold in the Pacific 

Northwest. This became known as the Manufactured Homes Acquisition Program (MAP). MAP 

was an unqualified success because of the cooperative agreement among all parties. Between 

1992 and 1995, approximately 40,000 homes were built under this program and the HUD 

standard was exceeded by a factor of two in overall heat loss and heating requirements. The 

region secured almost 30 average megawatts of savings (260 million kWh annually) from this 

program. 

When MAP ended in 1995, the state energy offices joined with the MH industry to continue 

operating a certification program for the industry, initially branding homes as Super Good Cents. 
3 

This new oversight effort became known as NEEM, which adopted specifications at the MAP 

level of energy efficiency. Today’s homes are branded as ENERGY STAR, Earth Advantage, or 

Eco-rated (a brand developed by the NEEM program). The underlying energy efficiency 

specifications have been expanded to cover items like duct testing, lighting, higher efficiency 

equipment, and better windows, but the core building shell requirements remain largely 

unchanged. 

NEW is the third-party administrator for the NEEM program. NEEM administers the technical 

specifications, performs research and engineering analysis, implements ongoing construction 

quality management procedures, and maintains a central database with home tracking. To ensure 

that qualified homes are recognized in the market for their unique value, NEEM also provides 

utilities with home certification validation. NEEM is supported by more than 74 utilities in the 

Pacific Northwest region and California that currently offer incentives for ENERGY STAR

labeled homes. Working with the Building America Partnership for Improved Residential 

Construction research team, NEEM is promoting the HPMH to the utilities and the MH industry. 
4 

2 Specifications for the High Performance Manufactured Home 

Table 1 compares current NEEM program requirements and the HPMH measures.

Table 1. Detailed HPMH Specifications

Component NEEM (Base) HPMH

Ceiling R-40 R-49 (R-45 net) 

Floor R-33 R-38

Wall R-21 R-26 (with average of R-5 foam)

Window U = 0.35 U = 0.22

Door R-5 R-5

Duct Leakage 6% of Supply No ducts

Target Uo 0.054 0.040

Heating System Electric Forced Air Furnace DHP/Electric Residential Hybrid Zonal

Lighting 1.4 W/ft2 0.7 W/ft2 (almost all are CFL or LED)

Infiltration 0.25 ACH (natural) and cfm50

targets 0.21 ACH (natural) 

Ventilation Whole-House Fan, 32 W 

continuous (0.1 ACH added) HPWH (0.14 ACH added) 

DHW (EF) 0.93 2.0 (HPWH)

Appliances and 

Miscellaneous

Standard refrigerator, 

ENERGY STAR dishwasher 

ENERGY STAR refrigerator and 

dishwasher/low-flow showerheads and 

faucet aerators

Notes: Uo, U overall (average hourly conductive heat loss for the building envelope on a per square foot basis); 

CFL, compact fluorescent lamp; LED, light-emitting diode; ACH, air changes per hour; cfm50, cubic feet per minute 

at 50 Pa; EF, energy factor
5 

3 Developing the Measures

All of the shell improvements and energy efficient mechanical technologies proposed for 

inclusion in the HPMH package are buildable, but require significant revisions to floor plans and 

factory processes. 

3.1 Improved Floor Insulation Effectiveness 

Removing the duct system will allow about 25% more insulation in the floor system, and it will 

now be possible to install insulation in contact with the subfloor. Plumbing supply lines will be 

installed with adequate insulation below them to prevent freezing in even the coldest climates. 

3.2 Rigid Insulation on the Exterior of the Wall Structure over the Sheathing

R-5 foam sheathing (3⁄4-in.-thick polyisocyanurate) will be installed on the exterior walls of a 

home, causing about a 25% reduction in the overall heat conductivity of the wall system. R-5 

foam sheathing will be supplied by the HPMH project and installed on a prototype home in the 

plant, with NEW staff on hand to monitor both the time implications for the added process and 

any potential impacts on building durability or insulation effectiveness. Construction job 

processes will be monitored in the plants to ensure buildability. 

3.3 Triple Glazed Windows

The HPMH specification calls for triple glazed low-E windows with a U-value of 0.22 or better. 

Two window manufacturers supplying a small portion of the MH industry (Cascade and JeldWen) do build R-5 windows, but the current leading supplier of the MH window market (Kinro)

is not building this grade of window. As an example, Jeld-Wen built a complete set of triple 

glazed low-E windows with an improved foam-filled vinyl frame design with a U-value of 0.20. 

These windows were recently installed in a laboratory home at PNNL in Richland, Washington. 

The windows were able to replace the existing window packages without significant design 

impacts in the PNNL laboratory home. Airtightness tests and light levels will be monitored 

before and after retrofit. 

 

3.4 Increased Ceiling Thermal Performance

The target performance for the vaulted ceiling assembly is U = 0.026 or R-45. The current 

assembly for the ENERGY STAR manufactured home program is U = 0.29 for vaulted ceilings. 

Insulation will be prototyped and costs gathered to change the ceiling insulation detail for 

conventional trusses, increase the truss heel dimension to approximately 8 in., or use hinged 

trusses to gain higher heel heights without increasing the overall transport height of the home. 

New roof insulation strategies for conventional trusses will include using a high-density R-30 

fiberglass batt in place of blown-in loose fill insulation in the area extending from the eave above 

the top wall plate (where the batt will be compressed but still have a higher R-value than loose 

fill insulation) and inward for 4 ft, where the attic depth will be sufficient to transition to blownin insulation for the rest of the attic. High-density blown cellulose at the eve will also be 

prototyped. 

3.5 Overall Uo Reduction

The combined impact of the changes to the thermal envelope described in sections 3.1 through 

3.4 would improve the overall Uo of the home. Uo is the average hourly conductive heat loss for 

the building envelope on a per square foot basis, per degree (°F) difference between inside and 
6 

ambient conditions. The changes will result in an improvement from the current NEEM 

specification of about 0.054 to a level of about 0.040. This represents nearly a factor of two 

reduction in heat-loss rate over the current national northern tier HUD standard (Uo = 0.079). 

3.6 HVAC System

Because the DHP will be combined with zonal electric heaters in each bath and bedroom, the 

existing electric forced-air furnace and duct system will be eliminated from the home altogether. 

The alternative HVAC system, based on a DHP, will be installed. The system is called a hybrid 

DHP zonal electric heating system, because the DHP will be combined with electric wall heaters 

or electric baseboard units (sizes range from 750 W to 2.0 kW depending on the climate and 

room size) located throughout the house. In the prototype homes the zonal electric backup units 

are expected to be from Cadet, a local producer, but any comparable product could be used. 

The electric resistance heaters supplement the primary heating system, which is the DHP. The 

high-efficiency DHP is located in the central living area, but it is sized with sufficient capacity to 

meet the entire home’s cooling load and its heat loss load under most conditions, especially if 

interior doors are left open. The DHP includes one or two wall-mounted indoor heads in the 

central space that operate nearly continuously, ramping up and down the fan speed in proportion 

to the amount of heating or cooling being performed by the unit. The continuous operation of the 

indoor head blower thoroughly mixes the room air to the point that air throughout the house gets 

turned over and conditioned by the DHP. Remote rooms will be conditioned indirectly most of 

the time, with the back-up electric resistance wall heaters supplementing as needed, especially in 

extreme conditions. Using a zone heating system of this type eliminates numerous thermal 

envelope penetrations attributable to the duct system. Although the NEEM program requires 

each home’s ducts to be tested online to ensure no more than 6 cfm50 air leakage per 100 ft2 of 

floor area, removing the ducts as a leakage path is expected to noticeably reduce whole-house air 

leakage. 

3.7 Domestic Hot Water System

Changing to an HPWH will significantly improve the efficiency of the DHW system, relative to 

a conventional electric tank water heater. Several products have been demonstrated in the Pacific 

Northwest in the last 2 years, and a few units have shown good performance characteristics in 

both laboratory tests and home installations. One product, AirGenerate, has just recently been 

approved as the only product compliant with Tier 2 of the NEEA Northern Climate Heat Pump 

Water Heater Specification. Ducted intake and exhaust systems are not available in the United 

States but are available elsewhere in the world (e.g., in Canada). A model from AirGenerate with

ducted intake and exhaust is currently going through UL and HUD approval processes in the 

United States.

To further improve the efficiency of the DHW system, a hot water conservation package would 

be added. Low-flow (1.75-gpm) showerheads and faucet aerators (1.0 gpm) would be included as 

well as water-conserving appliances. Given current regional laboratory results and field 

performance, a 50% reduction in the energy requirements for DHW over the base home was 

found as a result of the Seasonal Energy and Enthalpy Model (SEEM) modeling the team 

conducted. The project has identified three approaches to incorporating the HPWH into homes. 
7 

3.7.1 Design Option 1

In design option 1, the HPWH would be designed to draw air from the house crawlspace, transfer 

its heat into the DHW tank, and then exhaust the resultant cool air to the outside. There would be 

no impact on indoor air temperature or home ventilation systems. One plant’s DAPIA has 

presented this option to HUD, and HUD has ruled that a plant wishing to use this approach 

would need to submit a request for an alternate construction letter of approval, which could be 

used for all homes. 

3.7.2 Design Option 2

Design option 2 makes use of the HPWH as the central component in a ventilation system for the 

home. The HPWH would operate intermittently, drawing up to 300 cfm from the house and 

exhausting it outside, according to the hot water demands of the occupants. Daily run times 

would range between 3 to 6 h. Using the interior-coupled system, the overall ventilation rates 

provided by the HPWH could exceed the current NEEM and HUD standards by about 20%. 

Design option 2, though, is not a viable option because of the HUD approvals needed and 

because the high ventilation rate would necessitate providing significant make-up air for home 

pressure balancing. HPWH run times could in theory obviate the need for a separate wholehouse ventilation system, although this strategy could be in conflict with HUD standards. The 

spot ventilators (bath and range hood fans) currently used in the NEEM homes would still be 

required as part of the ventilation system. Because the HPWH would be moving more air when it 

runs than the conventional whole-house ventilation fan, fresh air make-up might need to be 

drawn in via dampered air inlets, possibly located in the bedroom closets and the water heater

compartment. Design option 2 is being included in this discussion because it was discussed with 

the industry and computer modeled in SEEM before being eliminated as a result of the 

impracticality of introducing the necessary volumes of outdoor air into rooms that are hopefully 

being largely conditioned indirectly from a single DHP indoor head located in another room. 

3.7.3 Design Option 3

The project team refined the heat recovery approach to create design option 3, where the 

AirGenerate HPWH would be fitted with a restrictor to bring the air flow rate down to 175 cfm. 

This is the minimum air flow that laboratory testing has shown not to significantly affect the 

HPWH unit’s performance. The 175-cfm HPWH airflow, coupled with a fan like the Panasonic 

WhisperGreen located in the master bathroom, could be set to provide 30 cfm continuously and 

bump up to 80 cfm when needed for spot ventilation. This combination could meet the required 

HUD ventilation rate (the HUD ventilation standard is 0.0035 times the square footage of the 

home up to a maximum of 90 cfm continuous for the whole house). The president of 

AirGenerate US toured a NEEM plant and commented that its 175-cfm restrictor would work in 

this configuration if the HPWH had free access to house air. The combination 

WhisperGreen/AirGenerate175-cfm option is in the process of being reviewed by the DAPIA for 

prototyping in one plant. Pressure diagnostic testing of a prototype home will help determine 

whether fresh make-up air will be required for pressure balancing. 

3.8 Lighting

Essentially 90% of all lamps will be high efficacy. Eco-rated home certification, which is a green 

home brand developed by the NEEM program, already requires 50% CFLs or equivalent. The 

project team anticipates using some modern LED lighting for accent application, with the bulk of 
8 

lighting being provided by conventional screw-in CFLs. The effect of this specification would be 

to reduce the power required by the lighting system by more than 50%. 

3.9 Appliances 

Appliances are the most difficult areas to address because new home buyers do not always 

purchase appliances when they buy a home, or they buy appliance at an appliance store after the 

home is installed. When a new HPMH home is sold, there is no way to require a new highefficiency laundry set, for instance. The HPMH specification calls for high performance 

ENERGY STAR (or ENERGY STAR Plus) appliances to be provided as part of the home 

package when a customer purchases new appliances with the home. These would typically 

include a refrigerator and a dishwasher. Homes that receive NEEM Eco-rated certification 

already have to meet this requirement. These products are included in the HPMH package so that 

both the hot water savings and energy savings associated with these efficient appliances are part 

of the complete energy efficient package. 

3.10 Wholesale Price to the Retailer

Table 2 presents the estimated measure installed wholesale price (which includes labor and 

materials) from the manufacturer to the retailer before any markup by the retailer for the 

elements of the HPMH specification. Wholesale price comprises the manufacturer’s cost of 

material, labor, and typical markup to the retailer. The variability in retail markup practices 

makes it difficult to estimate retail pricing for the energy packages, and retail pricing is not 

presented here. A retail markup of 15% to 20% for the energy packages, however, seems to be a 

reasonable estimate. The shell upgrades of R-21 walls with R-5 exterior foam and high R 

windows (U = 0.22 or better) represent the majority of the envelope wholesale price. Operations 

and maintenance (O&M) costs are listed for each measure to assist with benefit/cost analysis. 

The project team has presented its findings for regional utility program consideration. Shell 

measures are installed one time and there are no differential O&M costs. The HPWH filter has a 

positive O&M cost of $26 for cleaning the inlet air filter. The lighting system has a negative 

O&M cost from a reduction in changing bulbs over time, due to the longer life of energy 

efficient lamps compared to incandescent lamps. Washington State University Extension Energy 

Program’s (WSU’s) findings from its 2011 industry survey and market analysis project, “Cost 

Assessment for Manufactured Homes,” provide the basis for the estimates (Eklund and Gordon 

2011). Appendix A presents the measures studied by WSU to develop costs for by surveying 

home manufacturers, material suppliers, and wholesale/retail sources. 

Table 2. Measure Wholesale Price by Category

Category Notes $ (2011) $ (2006)

Measure 

Life 

(yr)

Annual 

O&M 

($, 2006)

Envelope Majority from walls and windows 4,277 3,816 45 —

Air Sealing and

Ventilation Whole-house exhaust fan 50 45 20 — 

HVAC System DHP and resistance wall heaters (less 

the cost of furnace and duct system) 4,701 4,194 20 — 

DHW HPWH 1,110 991 15 26

Lighting Compact and linear fluorescents 117 105 8 (13)

Appliances Dishwater and refrigerator 62 55 16 —

Total 10,318 9,205
9 

3.11 Modeling

The building energy use was predicted by a combination of numerical simulations and 

engineering calculations. SEEM was used to simulate heating, cooling, ventilation, and water 

heating energy use. The program combines building shell characteristics, thermostat settings, 

occupant behavior inputs, descriptions of heating and cooling systems, and duct distribution 

efficiency to develop an overall estimate of the energy requirements of a house. Additionally, 

engineering calculations calibrated by field studies were employed to determine the energy use 

for lighting and water heating. Annual gross lighting savings were calculated as lighting power 

density (LPD) multiplied by affected floor area and annual operating hours. This method 

assumes that all lamps in the house operate 1.5 h/day throughout the year.1 Concurrently, the 

modeling accounts for heating system interactions by changing internal gains for SEEM 

simulations. 

SEEM (version 0.94), the residential energy simulation program used for this analysis was 

developed by and for the NPCC and the NEEA and written by Larry Palmiter of Ecotope. It is 

the simulation engine used to generate heating and cooling energy savings estimates for the 

residential sector in the Northwest Power Plan and for the Performance Tested Comfort System 

incentive program, as well as numerous other utility program offerings. SEEM is also used 

extensively to support state building energy code revisions including, most recently, the revised

Washington State Energy Code and Oregon Residential Specialty Code.

The SEEM program consists of an hourly thermal, moisture (humidity), and infiltration

simulation that interacts with ducts, equipment, building shell, and weather parameters to 

calculate the space conditioning requirements of the building. It is based on algorithms consistent 

with current ASHRAE, American Heating and Refrigeration Institute, and International 

Organization for Standards calculation standards. The simulation generates outputs used in this 

analysis, which include building heat loss, heating equipment input energy, cooling equipment 

input energy, and ventilation equipment input energy. 

The DHP simulation capability is unique to SEEM. The method, based on findings from the 

Ductless Heat Pump Impact & Process Evaluation: Field Metering Report (Baylon et al, 2012), 

is calibrated to detailed observations of energy use in 91 houses pre- and post-DHP installation. 

Table 3 presents actual energy use and model predictions. The DHP used has a heating seasonal 

performance factor of 10 and a seasonal energy efficiency ratio of 20 in the main living zone 

with electric resistance in other zones. The field metering report shows that the DHP provides 

differing fractions of the total heating demand based on climate zone with the DHP supplying a 

higher percentage of total heating demand in warmer climates than in colder ones (heating 

fractions are heating zone 1 = 74%, heating zone 2 = 63%, and heating zone 3 = 45%). The DHP 

house-cooling fraction is assumed for the model to be identical to the heating fraction. Based on 

the small number of metered home data sets that present DHP cooling energy, metered data 

shows that occupants do not call for cooling when the outside temperature is 74°F or below. 

 

1RTF Meeting, Tuesday, September 28. Accessed February 9, 2012: http://www.nwcouncil.org/energy/rtf/meetings/2010/09/.
10 

Table 3. SEEM DHP Performance Calibration Results 

Method Heating Energy Use (kWh/yr) N

Mean SD

Pre-Installation Billing Data 9,347 3,892 91

Pre-Installation SEEM 66.8°F Set Point 9,331 4,135 91

Post-Installation Metered Data 6,484 3,894 91

Post-Installation SEEM 69.5°F Set Point 6,466 3,151 91

Notes: N, sample size or number of homes; SD, submetered data

The weather files used in all savings simulations are composite Typical Meteorological Year 3 

weather files that correspond to the heating and cooling climate zones the RTF has assigned to 

each Northwest county.2 The Typical Meteorological Year 2 directory contains the data files for 

the typical meteorological year data sets derived from 1961 to 1990. Typical Meteorological 

Year 3 covers 1991 to 2005. 

The three prototype houses used in the simulations were as follows: 

• 924 ft2, single-section manufactured house

• 1,568 ft2, double-section manufactured house 

• 2,352 ft2, triple-section manufactured house. 

These are standard analytical prototypes used by the NPCC to develop and evaluate energy 

forecasts and conservation plans for the region’s utilities. When the three prototypes are

weighted together by their market fractions, the result is an “average” house with a floor area 

equal to 1,572 ft2, which closely aligns with the average home size of what actually is being built 

in the region. This validates the prototypes as being representative. 

In all, Ecotope conducted 675 simulations with SEEM. This number includes the three 

prototypes; three heating climate zones and three potential cooling climate zones associated with 

each heating climate zone (nine heating-cooling climate zones in total); a baseline performance 

house; the current NEEM standard performance house; and three variations of the HPMH 

(ultimately, the team settled on one specification but investigated three possibilities related to 

HPWH installation scenario). 

The simulations used a HPWH compliant with Tier 2 of NEEA’s Northern Climate Heat Pump 

Water Heater Specification to determine the energy saving over a baseline home. This HPWH 

was used based on feedback from representatives of DAPIAs, who said that the best way to meet 

the various HUD rules was not to use any house air. This helped keep the number of HPWH 

simulations to a lower number. 

For this energy modeling exercise the HPWH was configured so that the tank is installed in a 

sound-attenuated buffered closet that draws air from the crawlspace and exhausts it outdoors. 

This HPWH configuration avoids conflicts with existing HUD requirements. The annual HPWH 

 

2 RTF Climate Zone Maps. Accessed February 9, 2012: http://www.nwcouncil.org/energy/rtf/zones/zonemapsx.htm. 
11 

energy use is based on mapping the annual crawlspace air temperature profile to a coefficient of 

performance versus temperature performance map. Water heating energy was calibrated to the 

equivalent of 17–18 gpd per occupant.3 The home occupancy was set at 2.2 based on a 2009 

survey of NEEM program houses. The baseline house gallons per day use is higher than the 

HPMH case because the HPMH specification calls for a 1.75-gpm showerhead, but the baseline 

assumes the federal maximum of 2.5 gpm. The HPWH installed in a closet might be the final 

solution or it could be another option. The HPMH project team will prototype other options in 

the future. 

The regional baseline (non-NEEM) home used for the SEEM energy modeling has U overall 

(Uo) = 0.0647 (current practice home being built in the Northwest, referred to as “HUD+” in 

Table 4, below). Minimum HUD standards require homes to have a Uo ≤ 0.079. The HPMH

home used in the SEEM energy model has a Uo = 0.040. In 2011, the project team personally 

interviewed representatives of each of ten manufacturing plants in the region to gather 

information on NEEM percentage versus current practice percentage versus modular percentage. 

NEW used the database and the prescriptive performance paths list in the database for each 

manufacturer, along with the 2010 composite weighted average baseline for non-NEEM home 

thermal performance. Production percentages were used and adjusted to reflect the mix of basic 

HUD homes and partially thermally upgraded homes for each manufacturer. The team then 

multiplied the R- or U-value for each component of each package by that package’s fraction of 

plant production to arrive at each manufacturer’s weighted average thermal package. Using the 

2010 production numbers to obtain each manufacturer’s market share of non-NEEM homes, 

NEW then multiplied each manufacturer’s average thermal package component R- and U-values 

by the respective market share percentage, which resulted in a composite, weighted average 

baseline, non-NEEM, thermal shell package for the industry as a whole. The regional baseline 

home has a window thermal performance value derived from a mix of aluminum and vinyl 

windows. The non-NEEM baseline home presented is intended to be conservative (at the energy 

efficient end of the likely range). R-19 walls were de-rated to reflect the actual value in a 2 × 6 

wall (R-17), but assemblies like R-11 batt insulation in a 2 × 6 wall cavity were not de-rated 

because commonly agreed-on thermal performance values for the assembly were lacking. When 

the baseline components are substituted for NEEM program requirements in the prototype home 

models, the resulting weighted average Uo comes in at 0.0647. 

3.12 Energy Use Calculations

Ecotope analyzed the HPMH specifications for their energy savings and cost-effectiveness 

potential, and the energy modeling results were presented to the NPCC’s RTF. Figure 1 presents 

the HPMH package energy savings over the regional baseline home produced by NEEMparticipating builders. Figure 2 presents total energy use in each of the climate types in the 

region, and Figure 3 further breaks out end uses in the home. Gaining RTF concurrence with 

cost-effective energy savings attributable to the new specifications is a necessary step to permit

BPA to consider moving forward with developing a program around the HPMH. 

 

3 RTF provisionally approved savings measure. Accessed January 4, 2013: 

http://www.nwcouncil.org/energy/rtf/measures/measure.asp?id=176. 
12 

Figure 1. HPMH annual energy savings (prototype weighted) 

Figure 2. Manufactured home total energy use (prototype weighted)

CZ1 CZ2 CZ3 CZ1 CZ2 CZ3 CZ1 CZ2 CZ3

HZ1 HZ1 HZ1 HZ2 HZ2 HZ2 HZ3 HZ3 HZ3

HPMH to Baseline 8,168 8,066 7,902 10,358 10,261 10,102 11,411 11,323 11,179

0

2,000

4,000

6,000

8,000

10,000

12,000

Savings (kWh/yr)

CZ1 CZ2 CZ3 CZ1 CZ2 CZ3 CZ1 CZ2 CZ3

HZ1 HZ1 HZ1 HZ2 HZ2 HZ2 HZ3 HZ3 HZ3

Baseline

"HUD+" 15,836 15,836 15,836 19,597 19,597 19,597 22,558 22,558 22,558

NEEM 12,957 12,957 12,957 15,567 15,567 15,567 17,570 17,570 17,570

HPMH

"Super NEEM" 7,668 7,771 7,935 9,239 9,336 9,495 11,147 11,235 11,380

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

22,000

24,000

Total Annual Energy Use (kWh/yr)
13 

 

Note: MELs, miscellaneous electric loads

Figure 3. House energy use by category

3.13 Savings

NEW and its partner, Ecotope, used SEEM to predict energy usage and the NPCC Pro-Cost 

model for the preliminary cost-effectiveness assessment. These tools were selected because BPA 

and the NPCC use them to assess energy savings and regional cost effectiveness. Broadly, the 

analysis methodology is to develop a representative set of prototypical houses in which energy 

use can be estimated through simulation tools. The energy savings are then used as inputs to the 

Pro-Cost calculations to estimate the benefit/cost ratio over the lifetime of the house. Table 4 

gives the results. 

Table 4. Energy Use, Savings, and Benefit/Cost Ratio

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

Baseline

NEEM

HPMH

Baseline

NEEM

HPMH

Baseline

NEEM

HPMH

CZ2 CZ2 CZ2

Energy Use (kWh/yr)

HVAC

DHW

Lights

MELs

CZ1 CZ3
14 

4 Next Steps

NEW will work with manufacturers, DAPIAs, and in-plant primary inspection agencies to 

develop the specific details of how various measures could be implemented. These details 

include how to meet structural and other code requirements, optimize cost efficiency in 

implementing measures, and ensure consistent outcomes when installing the measures. 

NEW will ask the MH industry to build prototypes of some of the equipment (DHP and HPWH) 

and building materials such as foam sheathing and windows in a few of its new NEEM homes to 

ensure correct operation. NEW will purchase materials or equipment in some cases or the 

homebuyer will purchase the equipment such as the DHP. BPA will provide funding for 

materials to be used in the prototype homes. Prototyping shell and mechanical innovations in the 

plants will include drawing new details or floor plans and working with suppliers to gain access 

to new equipment and materials.

The DHP measure involves significant changes to how the homes are designed and built, so 

NEW plans to hold a half-day session on designing, installing, and pricing DHP hybrid heating 

systems in Portland, Oregon, at Ductless Supply, a wholesaler interested in working with the 

industry to incorporate DHPs. NEW staff and the manufacturers will run the designs for the 

hybrid DHP through the DAPIAs used by those plants. The factories will need DAPIA and 

possibly HUD approval for the prototype homes. NEW will work with the plant staff and 

Ductless Supply to coordinate installation details and assess how well the DHP installation 

process might be incorporated into the plant’s regular production methods. The DHP-ready home 

will receive the DHP equipment when it arrives on site, with NEW staff present to assess the 

relative efficacy of this approach. NEW will visit the sites and train retailers to ensure proper 

O&M of the hybrid DHP system. Retailers will show the model homes. 

Other materials, such as foam sheathing and triple pane windows, should be fairly 

straightforward changes to implement. Materials will be provided by the HPMH project and 

installed in the plant, with NEW staff on hand to monitor both the time implications for the 

added process and any potential impacts on building durability or measure effectiveness. Two

NEEM homes will be used to prototype exterior R-5 foam sheathing, and one home will receive 

triple pane windows. NEW staff will also meet regularly with key groups, such as state MH 

associations, to bring the industry up to date on progress with the different shell and mechanical 

systems measures. These regular meetings will also maintain an active dialogue about 

positioning the concept of high performance in the MH market. 
15 

5 Discussion 

Electric energy savings ranging from greater than 8,000 kWh/yr up to nearly 11,000 kWh/yr over 

today’s regional baseline home are anticipated using the HPMH package across the entire Pacific 

Northwest. Total package cost in 2011 dollars is estimated to be $10,300. 

As technical specifications were developed, NEW assessed the relative market acceptance/value 

of the measures and scoped the levels of technological challenge involved with their 

implementation. For example, the process of designing and siting a DHP, running refrigerant 

line, and installing wiring and condensate drains will require three or more factory installs for a 

plant to become proficient enough to determine whether in-plant installation is feasible. HPMH 

homes can be sold with the DHP factory installed or DHP ready. The latter option requires the 

DHP to be installed on site. Retailers and factories need to be trained on how to sell DHPs and 

the finer points of design (e.g., where to locate the indoor head for optimal performance and ease 

of installation). The ideal install’s floor plan would have an alcove on the exterior side of the 

home where the DHP is installed and the refrigerant lines are run up and in without lengthy line 

runs. As an alternative to the alcove, DHP outdoor units can be wall-mounted on the non-tongue 

end of the home and refrigerant and power lines can be run along the steel I-beam and up into a 

closet behind the wall where the indoor head is located. 

Given the lack of suitable HPWH unit availability until just recently, the HPWH measure’s 

development has lagged behind other elements of the HPMH package. NEW staff and BPA will 

meet with AirGenerate personnel to discuss installing a unit to prototype in a NEEM home. The 

AirGenerate HPWH is currently the only HPWH that meets all the NEEA Northern Climate 

Spec Tier 2 criteria. AirGenerate is a pioneer of heat pump water heaters based in Houston, 

Texas. AirGenerate builds hybrid HPWH models that are available as 50-gal or 66-gal

configurations. Both models include a stainless steel tank, an auto-defrost system, a duct for 

exhaust air, and industry-leading efficiency with an energy factor of 2.4. There is also an AirTap 

add-on model that can convert any existing water heater tank to an energy-efficient one. 

AirGenerate is conducting laboratory and field testing on the HPWH with the help of BPA, 

NEEA, and the National Renewable Energy Laboratory. NEW is hoping to prototype the unit in 

one factory built home in the near future. 

In the past, customers or home manufacturers have given no negative feedback on R-5 exterior 

foam sheathed walls except for the associated material and labor cost. The triple pane R-5 

windows have only been retrofitted into a PNNL laboratory home in Richland, Washington, and 

have not been tried in a production line setting because of the high cost. High-density fiberglass 

batt over the top plate is easy to install (with a corresponding increase in production time) but 

requires the manufacturer to inventory another type of insulation, which is not normally used by 

most plants. 

NEW spoke on four occasions at industry association meetings, asking participants to give 

honest feedback to the team on the HPMH specification. Industry association membership 

comprises banks, finance companies, home retailers, material suppliers, and home 

manufacturers. The industry leaders have said that the appraisers will not give added value to the 

HPMH measures and will use simple dollars per square foot numbers to value even the HPMH. 

Low appraised values could cause a problem for anyone applying for a loan for the HPMH 
16 

homes. NEW staff spoke to Robin LaBaron of the National Home Performance Council, who 

reported that the council had just developed a new MH loan product for credit unions with an 

energy efficiency addendum that the appraisers could use to add the value of the efficiency 

upgrade to the value of the home (Hewes and Peeks, 2012). That would allow Fannie Mae and 

Freddie Mac to take into account P(principal)I(interest)T(taxes)I(insurance) and E(efficiency) 

instead of just PITI when qualifying buyers. 
17 

6 Conclusions

1. Electric energy savings ranging from greater than 8,000 kWh/yr up to nearly 11,000 

kWh/yr over today’s regional baseline home are anticipated using this package across the 

entire region. Total current package cost (2011 dollars) is $10,300. 

2. The higher cost of the HPMH home package could affect regional adoption of HPMHs in 

the Pacific Northwest. This economic factor could make it more difficult to secure a 

mortgage, affecting customers’ ability to finance a home. The utilities might be willing to 

incentivize the HPMH up to a level that could make the make the HPMH affordable. 

3. The MH industry is awaiting the results of the utility system’s cost-effectiveness 

calculations and possible incentive program. 

4. Feedback from retailers indicates that they might order a DHP in their model homes in 

the future. Retailers and customers can order new homes with hybrid DHP systems 

installed in the factory. A retailer can also sell homes to their customers as hybrid DHPready, with just the zonal system installed in the factory and a DHP circuit wired to a 

disconnect outside the home. 

5. The hybrid zonal DHP system can be adapted to many MH home floor plans. 

6. The noise reduction might be a significant benefit of DHPs compared to typical MH 

forced-air systems. 
18 

Bibliography

Baechler, M.; Hadley, D; Sparkman, R; Lubliner, M. (2002). “Pushing the Envelope: A Case 

Study of Building the First Manufactured Home Using Structural Insulated Panels.” Presented at 

the 2002 ACEEE Summer Study on Energy Efficiency in Buildings Conference, Pacific Grove, 

CA.

Baylon, D.; Larson, B.; Storm, P.; Geraghty, K. (2012). Ductless Heat Pump Impact & Process 

Evaluation: Field Metering Report. Prepared for Northwest Energy Efficiency Alliance. Seattle, 

WA: Ecotope, Inc. 

Baylon, D.; Davis, B.; Hewes, T. (March 2009). Summary of NEEM Manufactured Home Field 

Data and Billing Analysis. Seattle, WA: Ecotope, Inc. 

Baylon, D.; Davis, B.; Palmiter, L. (1995). Manufactured Home Acquisition Program: Analysis 

of Program Impacts. Prepared for the Bonneville Power Administration. Seattle and Olympia, 

WA: Ecotope, Inc. and Washington State Energy Office. 

Baylon, D.; Lubliner, M.; Davis, B.; Kennedy, M. (1990). Manufactured Homes Cost Data 

Analysis Report. Prepared for the Bonneville Power Administration. Seattle and Olympia, WA: 

Ecotope and Washington State Energy Office.

Code of Federal Regulations. (2001). “Manufactured Home Construction and Safety Standards.” 

Title 24, Part 3280. 

Eklund, K. (2008). Residential Heat Pump and Air Conditioner Research, Demonstration, and 

Deployment Improving Pacific Northwest Utility and State HVAC Programs—Project Report. 

Prepared for the National Association of State Energy Offices. Boise, ID: Idaho Department of 

Water Resources, Energy Division.

Eklund, K.; Gordon, A. (2011). “Cost Assessment for Manufactured Homes.” Prepared for the 

Bonneville Power Administration. Olympia, WA: Washington State University Extension 

Energy Program. 

Eklund, K.; Gordon, A.; Lubliner, M. (January 31, 2011). Strategic Recommendations to 

Improve Energy Efficiency in Manufactured Housing. A Report to the Bonneville Power 

Administration. Olympia, WA: Washington State University Extension Energy Program. 

Greer, R.; Hewes, T.; Peeks, B. (2004). Northwest Energy Efficient Manufactured Housing 

Program In-plant Inspection Manual. Salem, OR: Oregon Department of Energy. 

Hewes, T.; Peeks, B. (2011). Field Monitoring of Two Manufactured Homes in the Pacific 

Northwest. Prepared for the U.S. Department of Energy Building America Program under 

contract to PNNL. Corvallis, OR: Northwest Energy Works. 

Hewes, T.; Peeks, B. (2011). Retailer Survey. Prepared for the Bonneville Power Administration. 

Corvallis, OR: unpublished report. 
19 

Hewes, T.; Peeks, B. (2011). State of the Industry Report. Prepared for the Bonneville Power 

Administration. Corvallis, OR: unpublished report.

Hewes, T.; Peeks, B. (January 18, 2012). Personal communication with Robin LeBaron, Deputy 

Director of Fair Mortgage Collaborative. 

Lubliner, M. (October 2000). “WSU Energy House.” Automated Builder Magazine. 

Northwest Energy Efficiency Alliance (NEEA). (October 2009). “A Specification for Residential 

Heat Pump Water Heaters Installed in Northern Climates, Version 3.0.” 

NEEM. (2011). Northwest Energy Efficient Manufactured Housing Program Database. 

Corvallis, OR: Northwest Energy Works. 

Northwest Power and Conservation Council. (2010). Sixth Northwest Conservation and Electric 

Power Plan. Portland, OR: Northwest Power and Conservation Council. 
20 

Appendix: Cost Assessment for Manufactured Homes

In 2011 Washington State University Extension Energy programs conducted a cost study and 

literature review of potential technologies that could be considered for the HPMH program. The 

project considered a number of measures and examined several approaches to implementing each 

measure. NEEM-participating homebuilders were consulted for their experiences, concerns and 

levels of interest in exploring each of the measures and the various approaches. The resulting 

white paper was titled “Strategic Recommendations to Improve Energy Efficiency in 

Manufactured Housing” (Eklund et al. 2011). Following a brief summary of the options found, 

this appendix contains an excerpt from Eklund et al. 2011 (pp.8-12). The authors of this report 

have added comments in italics throughout the excerpted material, which is not part of the 

original work. 

Summary of Options Found in Literature Review

There are a number of envelope, HVAC and lighting technologies that have potential in 

manufactured homes. The most cost effective of these are probably envelope measures that are 

not significant variances from current practice. For example, advanced framing cuts production 

cost and increases efficiency. Blown in Blanket (BIB) type insulation systems are efficient and 

require little clean up. Rigid foam on the exterior of walls does not require special equipment or 

safety measures in plants. High efficiency windows may compare well to more dynamic 

measures such as Structural Insulated Panels. 

The excerpt from the white paper follows: 

High R Walls

Advanced Framing: the manufactured industry has moved away from 24-inch on center framing 

and insulated headers. The concerns identified by industry need to be addressed before this 

approach sees wide adoption, via direct technical assistance, and where needed, research and 

demonstration to identify issues with (and corrections for) construction processes, preservation 

of roof loading capability and avoidance of material failures that might lead to uneven siding or 

“nail pops.” In addition, even where manufacturers have used 24- inch on center framing and 

fully insulated headers, these construction practices may fall short of fully optimized advanced 

framing approaches, using more framing lumber at corners or interior walls than is necessary.

Structural Insulated Panels (SIPs): In 2000, Champion Industries constructed the first HUD code 

home using SIPs. While there were challenges associated with design of an all-SIPs house, the 

DAPIA approval process, and training of plant staff to accommodate new processes and 

materials, the home was successfully constructed in-plant, experienced fewer transportationrelated complications compared to other factory built homes, and was found to be more airtight 

than a typical HUD code home (Baechler, Hadley, Sparkman, & Lubliner, 2002). In addition, the 

manufacturer concluded that SIPs construction could be easily incorporated into the HUD code 

construction process, and could even increase production capacity, helping to offset increases in 

production costs. 
21 

In spite of these advantages, it’s important to note that no HUD code home has been built with 

SIPs since 2000. In one case, NEEM staff working in Idaho was actively engaged with a 

manufacturer that also owned a SIP plant opted not to construct their HUD homes with SIPs; 

even with that vertically integrated structure, the use of SIPs was not perceived as economically 

feasible.

Spray foam: In 2002, WSU and the Idaho Energy Division worked with Kit Homes to construct 

the Zero Energy Manufactured Home on the Nez Perce reservation in Lapwai, Idaho. The project 

specifications called for the use of spray foam (Icynene) in the walls, floors and ceiling. Kit’s 

experience with using spray foam within the factory setting was that using foam requires 

significant modification of the production process, with additional needs for worker safety, and a 

significant amount of cleanup post- installation. The foam industry has expressed interest in 

working with the manufactured housing industry and other interested parties to overcome these 

issues.

Blown in Blanket Type Systems (BIBs): These systems are widely used in site-built housing and 

produce better quality installation and higher R-values. Most of the systems are designed so 

preparation is quick and there is no significant cleanup. No extraordinary measures are required 

to ensure worker safety beyond those needed for batt insulation. Many manufacturers already use 

blown insulation for ceilings and even floors, and should be able to adapt to blowing insulation 

into walls.

Exterior foam walls: While exterior foam sheathing has made inroads into the site built market, 

and has even been used in some modular homes, this building practice has not, to our 

knowledge, been used in manufactured housing. According to WSU’s interviews with the 

DAPIAs, there are no structural issues with the use of foam sheathing in manufactured housing, 

when used in conjunction with the current shear system. Additional research may be required as 

to the maximum thickness of the foam, given transportation and on-site setup considerations. The 

project opted to develop this approach for potential inclusion in the HPMH package. 

High R Roofs

SIPs: As noted in the walls section, other than for demonstration purposes, SIPs have not been 

adopted by the manufactured housing industry, largely because of cost considerations. SIPs 

applications in attics can provide a conditioned space for HVAC duct chases and other 

mechanical systems, and can eliminate the house to exterior leakage related with the use of a 

vented attic. Also, for single section homes, SIPs can provide higher R-value throughout the roof 

assembly, including at the eaves, and may accordingly reduce the overall height of the home, 

avoiding transport height restrictions. 

Spray foam under roof decking: Application of spray foam to the roof deck could potentially 

provide similar benefits to the SIPs roof noted above, allowing for inclusion of mechanical 

systems in an unvented attic, and reducing house leakage. DAPIAs noted that the use of foam 

would require a change to the HUD requirements for attic venting (unless the assembly was fully 

enclosed), and the current production process that constructs the ceiling assembly as ceiling 

drywall glued to roof trusses and ridge beam would require significant re-design. 
22 

High density R-30 Fiberglass: a four-foot batt could be extended to the first 48” of the eaves. 

Typical insulation at eaves is about R-15. Use of high-density batt at the eaves would improve 

this by about a third, even with compression. Use of a commercially produced insulation baffle 

would assure adequate attic ventilation space, prevent wind washing and cause only the 

necessary amount of insulation compression.

Foam at eaves: Since high-density polyurethane foam is already used for gluing the bottom of 

the truss chord to drywall, it may be that this foam could be extended to cover the ceiling for the 

first 24” in from the eaves. Typical insulation at eaves is about R-15. Use of high-density foam at 

the eaves could potentially double this, but plants reported that the product currently being used 

is not designed to be installed at the depth being considered and is prohibitively expensive to be 

used in this manner. 

Foam blocks at eaves: Similar to the strategy noted above, this approach would use a foam 

wedge to baffle blown roof insulation, and add high-density foam insulation to the eaves to 

significantly increase the R-value. This product is currently unavailable, but could be developed 

if program standards included a requirement for full insulation value at the eaves.

High density R-30 Fiberglass: a four-foot batt could be extended to the first 48” of the eaves. 

Typical insulation at eaves is about R-15. Use of high-density batt at the eaves would improve 

this by about a third, even with compression. Use of a commercially produced insulation baffle 

would help assure adequate attic ventilation space, prevent wind washing and cause only the 

necessary amount of insulation compression. The project opted to develop this approach for 

potential inclusion in the HPMH package. 

High R Floors

SIPs: When Champion constructed their all SIP home in 2000, they chose to locate the duct 

system in the crawlspace. If used in conjunction with a SIP cathedralized attic, the duct system 

could be brought into conditioned space. The underfloor plumbing system, on the warm side of 

the floor insulation with the plants’ present floor system, would be outside the conditioned space 

of the home and would require insulation to prevent pipe freezing. No plants reported interest in 

making the capital investment that would be required to change their production lines to 

accommodate SIPs construction. 

Spray foam: In the Zero Energy Manufactured Home constructed in 2002, the manufacturer 

needed to apply the foam to an R-11 belly blanket, because the foam wouldn’t adhere to the belly 

fabric. The research team working on the home also determined that the trunk ducts should not 

be foamed, to allow for beneficial conductive heat loss from the ducts to the home (regain). The 

plant reported a significant cost increase and production impacts from this spray foam 

application. 

Fiberglass batt and blanket: Many manufacturers currently install R-33, via batts between floor 

joists and blankets under the entire floor assembly to meet the present NEEM specifications. 

Others install a single fiberglass blanket under the entire floor assembly and blow-in loose fill 

insulation on top of that to achieve the full R-value. 2x6 floor joists constrict the depth of the 

insulation in the 24- to 36- inches of the floor outboard of each of the trailer chassis I-beams. 
23 

Switching to 2x8 floor joists would help improve the insulation in the “outrigger” areas, but the 

added house height can be problematic when it comes to home transport. If the heating duct can 

be removed from the floor, the possibility arises to add more insulation to the center section of 

the floor – the “belly” area. The project team opted to develop this approach for potential 

inclusion in the HPMH package. 

High Efficiency Windows

Production windows are now approaching U factors of 0.2. An issue with these windows is 

whether they employ multiple panes that may make them too heavy or fragile for transport in a 

HUD Code home. This should be investigated and tested for potential inclusion in the HPMH 

package. If they work, they may be at the top of the list for acquisition, as they are likely to be a 

part of future versions of the IECC. 

HVAC Equipment and System Technologies

Ductless heat pumps: Ductless heat pumps (DHPs) have become a popular option in the site built 

industry, in new construction and retrofit applications. Manufactured homes, because of their 

layout, may be good candidates for this technology, utilizing a central DHP, in conjunction with 

zonal electric resistance heating in bedrooms. Multi-head systems may allow for further 

reductions in zonal electric heating, at higher cost and with some penalty to DHP system 

efficiency. Another potential element of a DHP hybrid electric zonal heating system that needs 

further research is the use of transfer fans to move conditioned air from the central zone into the 

back rooms. (HUD’s requirement for a heat source in each habitable room may be not permit the 

full benefit of this approach from being realized.) Further investigations are also needed into any 

potential requirements for HUD listing of equipment or code conflicts that may need to be 

resolved to best accommodate DHPs. The project team opted to develop this approach for 

potential inclusion in the HPMH package. 

Variable refrigerant flow central heat pumps: Variable refrigerant flow (VRF) heat pumps utilize 

technology similar to the ductless heat pump noted above, achieving significantly higher 

efficiencies than traditional air source heat pumps. Nordyne has recently begun producing a VRF 

system that will work in manufactured housing – additional independent research is needed to 

determine viability of this system in manufactured housing and in the Pacific Northwest 

climates.

Heat Pump system commissioning and controls: Heat pumps need to meet specifications for 

charge, flow, thermostat setup and outdoor lockout to operate correctly. Heat pumps meeting the 

Northwest’s PTCS specification are estimated to achieve an average of 900 kWh annual savings 

over heat pumps without commissioning. 

Electric furnaces with improved blowers and good duct design: Given that the majority of 

manufactured homes are shipped with electric furnaces, it would be useful to examine how this 

technology could be improved. The use of a blower with an electronically commutated motor 

(ECM) can result in savings of 30% and upwards, when compared with a standard blower motor. 

The use of ECMs also introduces opportunities to mix air from a centralized DHP system, and 

may also allow for use of the blower fan as an efficient ventilation system. It’s important to note 
24 

that ECMs are very sensitive to high static pressure, requiring intelligent duct design that keeps 

the static pressure to .5 inches of water column (125 Pa) or less. 

Electric Zonal heating and cooling: The use of zoned heating and cooling systems has the benefit 

of eliminating the need for a ducted distribution system. The disadvantages cited by the industry 

are higher system costs, and eliminating the option of post setup installation of a heat pump or 

central air conditioner (this argument holds less weight given the increased availability of 

ductless heat pumps). 

Other systems: Other technologies with wide deployment throughout the United States, but with 

less use in the Pacific Northwest, include residential economizers and evaporative coolers. 

Evaporative coolers have long been used to cool manufactured homes in southwest Idaho and 

eastern Washington. Demonstration of new technologies incorporating these methods of cooling 

may expand their use in manufactured homes. 

Domestic Hot Water Technologies

Heat Pump Water Heaters: Heat pump water heaters (HPWHs) are a high visibility technology 

beginning to be heavily promoted throughout the country. In the heating-dominated Pacific 

Northwest, extracting heat from the conditioned space to heat water has the effect of delivering 

space cooling during the many months of the year when it very likely is not desired. HPWH 

configurations that may be appropriate for the Pacific Northwest include placing the HPWH in a 

sectioned-off utility room where colder temperatures are not a significant issue, or using the 

HPWH to exhaust cooled air from the house to the exterior, which has the added benefit of 

providing heat recovery ventilation. If the home is heated with a ductless heat pump, the 

combined system acts in effect as a two-stage heat pump. If HPWHs are to be promoted, they 

should meet and be installed to NEEA’s Northern Climate Specification (Northwest Energy 

Efficiency Alliance, 2009) to ensure savings are obtained and the units are installed properly. 

The project team opted to develop this approach for potential inclusion in the HPMH package.

Plumbing system design: “Structured plumbing” systems, which reduce energy and water losses 

through designs that limit trunk and branch runs, insulate all pipe, incorporate circulation loops 

and a recirculation pump, have the potential to save 80% or more of the waste water and hot 

water in a “typical” home. Manufactured housing, with single story layouts, has the potential for 

a lot of wasteful design (distances of 60 feet from water heater to appliance are not unheard of in 

multi-section homes. WSU has had discussions with Gary Klein of Affiliated International 

Management on the potential of structured plumbing approaches in both the IECC and HUD 

codes, as well and energy and water conservation programs. 

Lighting Technologies

Compact and other fluorescents: While compact fluorescent lighting (CFL) is widely available in 

retail, and CFLs are widely used in energy efficiency programs for site built homes, WSU’s 

survey of the northwest manufacturers only identified five of ten manufacturers who shipped 

CFLs with the home, and then only when the customer selected the Eco-Rated or Earth 

Advantage options. Manufactured housing has a lot of untapped potential in this regard. The 

project team opted to specify an efficient lighting target as a fraction of installed lamps for 
25 

potential inclusion in the HPMH package. Alternative design strategies for fluorescent 

technologies, such as dimmable T8 and T5 lamps in wall and ceiling valances, have proved to be 

effective and aesthetically pleasing in demonstration homes such as the WSU Energy House 

(Lubliner, 2000). 

LEDs: LED technology has progressed significantly in the last decade, though costs remain high, 

especially for lamps with better color rendering ability. A demonstration home using LEDs 

might be the best strategy for deploying this technology in the manufactured housing 

marketplace.

Solar Technologies

Solar ready: Given the high first costs for both solar thermal and PV systems, neither technology 

is a cost effective option for the mainstream manufactured home buyer. However, including a 

“solar ready” option facilitates the after-market installation of solar technologies by 

implementing in-plant provisions such as roof load calculations, roof penetration flashing and 

mounting systems, pre-installed piping and conduit chases, and mechanical room design. 

Incremental costs are estimated at $300-$2100 (in climates with reduced snow loads, the existing 

roof design can accommodate the weight of the panels, reducing the need for a roof upgrade). 
DOE/GO-102013-3816 ▪ February 2013

Printed with a renewable-source ink on paper containing at 

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