“The market has spoken. Energy efciency sells,” said Todd Louis,
vice-president of Tommy Williams Homes in Gainesville, Florida.
Since partnering with the U.S. Department of Energy’s Building
America program in 2004, Tommy Williams’ production homes have
outsold the competition, with sales increasing year after year in spite
of the recession. All Tommy Williams’ homes achieve HERS scores of
under 60, while homes built to Florida’s state energy code have
scores as high as 85. Tommy Williams achieves this high performance
at less than $3,500 in added cost per home.
Tommy Williams uses a system engineering approach to achieve
high-performance with off-the-shelf products and many standard
building techniques. Walls are 2x4 16-inch on center, but extra attention
is given to air sealing all holes and cracks around ducts, wiring, and
plumbing. Foam gaskets are installed at the sill plate and top plate, and
air blocking is installed under attic kneewalls to achieve blower-door
test results of 2.7 ACH50. Ducts are mastic sealed and protected from
solar heat gain by a radiant barrier installed in the attic. Ladder T
framing provides extra room for insulation in the walls, which are lled
with blown berglass; R-30 blown berglass covers the ceiling deck
of the vented attic.
The walls behind showers and tubs are lled with blown-in berglass
that fully aligns with the air barrier material installed behind the tubs
to ensure the thermal performance of the insulation.
BUILDING TECHNOLOGIES OFFICE
Tommy Williams Homes
Longleaf Village & Belmont | Gainesville, FL
PROJECT INFORMATION
Construction: New home
Type: Single-family
Builder: Tommy Williams Homes
www.tommywilliamshomes.com
(352) 331-8180
Size: 1,470 to 3,045 ft
2
Price Range: $190,000 to $370,000
Date Completed: 2010
Climate Zone: Hot-humid
Team: Industrialized Housing
Partnership
PERFORMANCE DATA
HERS Index: 48-58
Projected annual energy
cost savings: $930
Incremental cost of energy-
eciency measures: $3,314
Annual mortgage
payment increase: $265
Annual net cash flow
to homeowner: $665
Billing data: Not available
R
(Photo top left) Tommy Williams is so confident of its homes’ energy performance,
it oers to pay buyers’ electric bills for a year. “This is more than a sales incentive;
it tells our customers that we stand behind our energy-ecient features,” said Todd
Louis, vice-president of Tommy Williams Homes in Gainesville, Florida.
Building America Case Study
Whole-House Solutions for New Homes
“The most important innovation we use is taking a whole-house
approach. We’re not just giving customers a few energy-efficient
options…we’re putting them all together to create a much better home.”
Todd Louis, vice-president of Tommy Williams Homes in Gainesville, Florida
Lessons Learned
•
The SEER 16, HSPF 9.5 heat pump is right sized (ACCA Manual J)
rather than oversized so it will stay on long enough to adequately
dehumidify while it cools.
•
Outdoor air is drawn to the return side of the air handler through
a lter that supplies fresh air when the air handler is running to
positively pressurize the house and keep out humid air.
•
Bathroom fans are equipped with a moisture sensor and run
automatically when indoor humidity levels are above a set point.
•
Low-emissivity windows, covered porches, and a radiant barrier in
the attic minimize solar heat gain.
•
Tommy Williams continues to outsell the competition, even at higher
prices. In one development, where Tommy Williams and a competitor
each own half of the 550 lots, Tommy Williams sold 23 homes in
2010 while the competitor sold only 16, and Tommy Williams sold at
$139.13 per square foot compared to the competitor’s $126.34. The
energy-efcient features of a Tommy Williams home increase its cost by
about $3,300, compared to a similar home built to minimum Florida
code. When nanced as part of a 30-year mortgage, this increases a
homeowner’s mortgage by $265 a year, but the reduction in energy bills
averages $930 a year for a net gain to the homeowner of $665 per year.
KEY ENERGY-EFFICIENCY
MEASURES
HVAC:
• SEER 16, HSPF 9.5 heat pump
(sized using ACCA Manual J)
• Variable-speed air handler
• Ventilation from a fresh-air intake
to the return side of the air handler
• Moisture-sensor-controlled
ENERGY STAR exhaust fans
Envelope and Windows:
• Slab-on-grade foundation
• R-15 blown-in fiberglass insulation
in 2x4, 16-inch o.c. walls with brick
and fiber cement siding
• R-30 blown-in fiberglass insulation
in vented attic with a radiant barrier,
knee wall air barriers, and foam
gasket sealing
• Windows: Low-E, double-pane
insulated vinyl windows, U=0.35,
SHGC=0.25
• Blower door test = 2.3 ACH50
Lighting, Appliances,
and Water Heating:
• 100% CFLs
• Tankless gas water heater (0.83 EF)
For more information, please visit:
www.buildingamerica.gov
Tommy Williams Homes
addresses common thermal
bypass issues like heat loss
around tubs and showers
installed on exterior walls
and at attic kneewalls by
filling the wall cavities with
blown fiberglass and covering
them with a rigid air barrier
material to prevent heat loss
due to air flow.
Building America Case Study Whole-House Solutions for New Homes: Tommy Williams Homes
2
For more information, visit:
www.buildingamerica.gov
PNNL-SA-87331 April 2012
Printed with a renewable-source ink on paper containing at
least 50% wastepaper, including 10% post consumer waste.
The U.S. Department of Energy’s Building
America program is engineering the
American home for energy performance,
durability, quality, aordability, and comfort.
