Treating the Whole Home as a System

Check out the energy efficiency secrets of David Weekley Homes' success.

David Weekley Homes is the largest privately held homebuilder in the United States, and Weekley says the reason is that the company looks at the whole house as a system.

"It's not just adding an energy efficient feature here and a component there. We engineer the house so you get the most bang for every energy dollar invested," says Weekley, company president. "This isn't something that a builder can do just by flipping a switch or spending more money. You have to fail a lot of blower-door tests and duct-leakage tests first. It took us a while to get to where we could build our homes as tightly as we needed to, to train up our air-conditioning contractors to where their ductwork was as tight as it needed to be and our insulation contractors to air-seal in the way they needed to."

Mike Funk, a quality coach for David Weekley Homes, says all homes in the company’s Houston region are built to qualify for certification by the U.S. Department of Energy's Builders Challenge.

Despite multiple house plans and consumer choice options, Weekley's Builders Challenge-certified homes share several energy efficient characteristics. Wood-framed walls are air-sealed and then insulated with R-13 unfaced fiberglass batts and an external covering of R-2 polyisocyanurate rigid foam sheathing. Sloped ceilings are insulated with R-19 unfaced fiberglass batts, and flat ceilings are insulated with R-38 paperless batt or blown insulation. A radiant barrier helps keep attics cool. Sill seal serves as a gasket, keeping out air, moisture and bugs between the foundation slab and the sill plate. Funk says blower-door tests average 0.25 in natural air changes per hour.

Homes are equipped with a 95 percent efficient gas furnace with a variable-speed motor. A fresh-air ventilation system with a MERV 11 air filter and jump ducts between bedrooms ensures that clean, conditioned air is distributed evenly throughout the home. Ducts are mastic sealed; testing shows a low average leakage of 2.2 percent. Vinyl-framed, low-emissivity double-pane windows have a solar heat gain coefficient of 0.3 to 0.34.

To ensure durability in the highly humid Houston climate, homes are sided with fiber cement siding and painted with exterior paints containing mildewcides, doorjambs are designed for water and rot resistance, and concrete backer board is installed behind tubs and showers. A pest defense system is installed in the walls, and the homes are borate-treated for termites.

Here are some of Weekley homes’ energy-efficient features:

  • HERS scores: 55 to 70, with an average of 65
  • Attic insulation: Not conditioned, R-38 blown-in cellulose, with radiant barrier
  • Wall insulation: R-13 fiberglass batts, R-2 polyisocyanurate rigid foam sheathing
  • Roofing material: 240-pound asphalt shingles
  • Foundation: Concrete post-tension slab
  • Ducts: Jump ducts, tested at maximum 3 percent leakage, average at 2.2 percent
  • Air handler: In the attic, 95 percent-efficient furnace with a variable-speed motor
  • Air sealing: Average testing at 0.25 natural air changes per hour, sealed penetrations, sill seal between slab and exterior plate
  • Windows: Vinyl frame, low-E, 0.3 to 0.34 solar heat gain coefficient
  • Water heating: 64 percent-efficient natural gas
  • Ventilation: MERV 11 with variable-speed 15 SEER system
  • Lighting and appliances: Minimum 60 percent CFLs
  • Commissioning/certification: Builders Challenge, Energy Star, MASCO Environments for Living Platinum

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