DOE Tour of Zero: Taft School by BPC Green Builders
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BPC Green Builders constructed this 3,891-square-foot home in Watertown, Connecticut, to the performance criteria of the U.S. Department of Energy Zero Energy Ready Home (ZERH) program.
This home on the campus of the nearly 100-year-old Taft School in western Connecticut was designed to fit in with its historic surroundings while the energy-efficiency features built into the home help it serve as a living laboratory for the students.
The 13.1 kW of solar electric panels and the solar thermal water-heating system helped the home achieve a Home Energy Rating System (HERS) score of -14. In its first year of operation, the solar electric system has already produced four times as much power as the home is using.
Short, efficient duct runs were achieved by locating the high-efficiency air source heat pump centrally in home.
Low-VOC finishes are among the features that helped the home earn DOE ZERH program certification. Additional certifications to the Passive House Institute U.S., LEED for Homes platinum level, and the National Association of Home Builders’ National Green Building Standards are pending.
ENERGY STAR-rated appliances, including a high-efficiency refrigerator, dishwasher, and clothes washer, reduce energy and water use in the home.
Triple-paned ultra-efficient windows use advanced technology coatings that retain heat in the winter and block heat in the summer.
The majority of the home’s heating load can be satisfied by internal heat given off by people, appliances, and equipment, and solar heat gain passing through the high-efficiency windows.
A motion-sensor-controlled circulator pump quickly delivers hot water to EPA WaterSense-labeled fixtures in the bathrooms, reducing water and energy usage.
The energy-sealing gasket visible on the foundation wall helps ensure an airtight connection with the double-wall assembly above.
The basement walls’ interior framing is set in 3 inches from the concrete to allow space for an insulating blanket of closed-cell spray foam that is applied directly to the concrete. Additional cellulose insulation is blown into the framing for high-efficiency basement wall insulation (R-32.5).
The home’s above-grade walls consist of two 2-by-4 stud walls with a 4-inch gap between the walls, providing 11 inches of insulated space.
BPC Green Builders’ ultra-efficient wall insulation includes 2.5 inches of closed-cell spray foam and 8.5 inches of dense-packed cellulose in the double-wall framing plus a continuous exterior thermal blanket. The total R-55 wall insulation is substantially higher than required by code.
The ultra-efficient attic insulation is achieved with a thick blanket of blown cellulose that covers the attic floor and rafters. The resulting R-100 attic insulation is substantially higher than required by code.
The continuous exterior thermal blanket uses rigid insulating sheathing that is taped at the seams to also serve as an air and water barrier.
A corrugated house wrap covers the sheathing, providing an air gap that ensures drying under the siding.
“You feel like you’re wrapped in 100 wool blankets.”
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“As soon as you walk into this house, you can tell it’s sound, it’s airtight. You feel like you’re wrapped in 100 wool blankets. It’s so warm, you would never know that it’s been below 0 this past few weeks.”