TechPractices are outstanding housing projects throughout the U.S. where innovative technologies are implemented. Builders and remodelers can use these examples as models for projects of their own.
|Palm Harbor Homes Snapshot
||Palm Harbor Homes
||Manufactured home model line
||$46,000 to $80,000
||Technical assistance supported by EPA and DOE grant
||Energy Star Manufactured Housing Line, Duct-Tightening, Tilt-Up
Roofs, Ventilation Control System
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.
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
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
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.
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.
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.
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.
Do you have a specific question? Try the contacts listed below:
Palm Harbor Homes
15303 Dallas Parkway, Suite 800
Dallas, TX 75248
Energy Star Homes Program
U.S. Environmental Protection Agency
401 'M' St., SW
Washington, D.C. 20460
Florida Solar Energy Center
1679 Clearlake Road
Cocoa, FL 32922-5703
U.S. Department of Energy
1000 Independence Ave. SW
Washington, D.C. 20585-0121