DOE Tour of Zero: Kalamazoo Infill Home by Kalamazoo Valley Habitat for Humanity
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Kalamazoo Valley Habitat for Humanity built this 1,032-square-foot affordable home in Kalamazoo, Michigan, to the high performance criteria of the U.S. Department of Energy Zero Energy Ready Home (ZERH) program.
The energy-efficient home fits into the neighborhood from an architectural perspective but is a standout in energy efficiency, costing its homeowners about $60 a month in energy bills.
Under the lifetime asphalt shingles, Habitat installed ice-and-water shield over the taped OSB roof decking 6 feet up from the eaves, in all of the valleys, and around all roof penetrations. An 8-inch strip of ice-and-water shield was also applied at the edge of the roof decking and draped down over the subfascia. Then drip edge was installed, then another strip of ice-and-water shield was applied to cover the roof-drip edge seam. This double layer of protection helps keep water from getting behind the drip edge and rotting the subfascia.
ENERGY STAR appliances and LED lighting help reduce energy bills for homeowners.
The dropped ceiling in the hallway conceals the main trunk line for the duct system, which distributes heat from the 97% AFUE gas furnace. The furnace can modulate down to 5 kBtu to match the home’s low heating loads. The small round hole in the soffit is a heat register for one of the 2.5-inch-diameter supply ducts that connect to the trunk duct.
The Habitat affiliate makes its own “ICFs” using donated rigid foam that is set in place to create a form for pouring the foundation footing wall. After installing plumbing, the area within the perimeter was backfilled with sand and topped with a layer of 2-inch XPS (R-10) that was laid down across the entire area including top of the foundation wall and additional slab edge insulation was installed around the perimeter and the slab was poured. The above-grade walls are also sheathed with 2 inches of XPS, creating a continuous layer of insulation from the bottom of the footings to the trusses.
Every roof truss is anchored to a wall stud with hurricane strapping to help resist uplift in high winds.
The 2-by-6, 24-inch on-center walls of the home are sheathed with 2 inches (R-10) of rigid foam. An additional 2 inches of foam is installed between the studs. Plywood is used only at the corners for wind bracing. Baffles will carry air from soffit vents to ridge vents to help keep the attic dry.
Drywall was installed as an air barrier above the central hallway duct chase prior to installing the trunk ducts.
Triple-pane windows provide superior thermal performance. The vinyl-framed, argon-gas-filled windows have nearly invisible low-emissivity coatings to slow heat transmission, while still letting n plenty of daylight.
Any heat recovery ventilator ducts that were installed in the attic were covered with 2 inches of closed-cell spray foam. Closed-cell spray foam was also used to seal all top plates and seams in the ceiling drywall and to cover any holes for wiring, plumbing, and electrical boxes.
“Our energy bills are lower than in our apartment, and we have no bugs.”
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“The home is so quiet that you can’t hear the traffic. ... Our energy bills are lower than in our apartment, and we have no bugs at all in the home. The past few days have been very warm and we haven’t had to turn the air conditioning on yet. The house is easy to maintain and very comfortable.”