TechPractices: Palm Harbor Homes, Dallas, TX

PATH's Technologies in Practice are large scale housing projects throughout the U.S. where innovative technologies are being installed and used. Information is presented from the viewpoint of builders and remodelers who can use these examples as models for projects of their own.

Summary

How do you get the quality control and cost savings of manufactured housing, but with the energy savings of a tightly-built custom home? Palm Harbor Homes has a line of HUD-Code homes that is the first to qualify for the Environmental Protection Agency's (EPA) Energy Star Homes Program label. The improvements add some cost, but monthly energy savings and mortgage credits exceed the modest increase in the purchase price, making the homes more attractive to buyers. Energy Star certification can also increase the home's value.

Details

The goal of the Energy Star Program, which was originally intended for site-built housing, is to motivate builders to increase energy efficiency and life-cycle cost savings through an integrated design and certification process. To qualify for the Energy Star label, a home must use at least 30% less energy for heating, cooling and water heating than the CABO Model Energy Code requires for the home. Palm Harbor's builders achieved this by tightening ducts, increasing R-values, and using efficient HVAC systems and water heaters.

Tightening the HVAC ducts was a major energy-saver. The Florida Solar Energy Center (FSEC) provided technical assistance and in-plant training for duct-tightening and other practices. Connections are sealed with mastic and extra attention is paid to connections between ducts and plenums at mating lines between house sections. These and other changes slashed duct leakage to from approximatley 70 cfm to less than 10 cfm for each half of the home.

The team then tackled the equipment itself, and found other areas to improve. The air-to-air heat pump HVAC systems now feature a seasonal energy efficiency rating of at least 12 and a heating season power factor of 7.6. The water heaters have an energy factor of 0.9. Insulation values in roofs are R-33, floors are R-22, and the standard 2 x 4 exterior walls are R-13. The 2 x 6 walls, a popular alternative, have R-19. Additional energy-saving components include double-insulated windows, radiant barrier-laminated roof sheathing, and a Fan Recycler ventilation control system, which automatically provides a supply of fresh, filtered air, even when the HVAC system is not running. The Fan Recycler unit is wired to the air handler fan and brings in air through an external ventilation duct connected to the return air duct. In addition to being quieter than most exhaust fans in manufactured housing, the system results in improved air quality.

Palm Harbor's homes vary in size from 1,250 sf to 2,400 sf, and are produced as double- or triple-wides. Roof pitches of 5 in 12 or greater are accommodated with tilt-up roofs.

Installation/Construction

The major steps in qualifying for the Energy Star rating included tightening HVAC ducts, better insulation, double-glazed windows, and insulated roof decking. To tighten the crossover ducts where the house sections join, the company used some new tools: one cuts a neat hole in the plenum box, where mastic sealer is applied; another tool tensions and cuts the straps attaching the flex duct liner to the collar for a more precise fit.

Benefits/Costs

In Raleigh, the homes sell for between $40 and $45 per square foot, or approximately $46,000 to $80,000. Square footage, degree of interior finish, and roof pitch are major factors affecting price. Buyers can qualify for Energy Star Mortgages.

The builder guarantees that the monthly energy bill will be below a stated maximum ($138 for a double-wide, depending on the region), or they'll pay half the overrun. Although Palm Harbor's homes were already energy-efficient compared to other manufactured homes, the improvements lowered electricity use from 20.7 kWh/day to 13.7 kWh/day. The cost premium for the improvements is estimated at $150 to $200 per house, primarily for ductwork tightening.

The improvements in the Palm Harbor homes were supported in part by a grant from the U.S. Department of Energy and the U.S. Environmental Protection Agency, for FSEC's technical assistance. It may be difficult for other manufacturers to achieve the same results without significant cost increases, especially in cold climates. Although Palm Harbor got free technical assistance to determine the most cost-effective ways to save energy, the EPA asserts that from a business perspective it is well worth paying for expertise to re-engineer a home product. Energy reduction will more than pay for the mortgage increase due to improved construction and technical analysis, resulting in lower total monthly housing costs for the homeowner. Other programs may be available for free or low-cost technical assistance; Contact the EPA.

Code/Regulatory

The HUD Code is somewhat less stringent in the area of energy performance than the model building codes. Energy Star's criteria were intended for site-built housing.

The manufacturer reports that many customers are choosing exterior walls with the optional 2 x 6 studs at 16 inches on center. The 2 x 4 walls are still standard, at 12 inches on center to meet the HUD Code's wind load requirements. In addition to better insulation, the 2 x 6 wall is value-engineered to be more cost-effective.

Feedback

The manufacturer has installed several hundred Energy Star-rated homes, primarily in North Carolina. Because of the ease with which Palm Harbor achieved the Energy Star rating, the company has instituted the changes in a quarter of its plants, with the goal of half by the end of 1998. Because of the savings achieved by simply tightening the ducts and plenums, the company plans to make this standard practice in all its plants. To ensure proper equipment and energy performance, a field inspection protocol is being developed with the EPA.

Contact(s)

Do you have a specific question? Try the contacts listed below:

Palm Harbor Homes
15303 Dallas Parkway, Suite 800
Dallas, TX 75248
972-991-2422;
www.palmharbor.com

Energy Star Homes Program
U.S. Environmental Protection Agency
401 'M' St., SW
Washington, D.C. 20460
888-STAR-YES
www.epa.gov/homes

Florida Solar Energy Center
1679 Clearlake Road
Cocoa, FL 32922-5703
407-638-1400

U.S. Department of Energy
1000 Independence Ave. SW
Washington, D.C. 20585-0121
202-586-9472