DOE Tour of Zero: MassDevelopment Devens Green Zero-Energy Community Custom Home by Transformations Inc.
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The homeowner of this certified U.S. DOE Zero Energy Ready Home in Devens, Massachusetts, was used to paying $500 a month for utility bills in his old home. The first utility bill in his new high-performance home was a pleasant surprise –- a $58 credit from the utility company.
Behind the vinyl siding is a super-insulated building envelope with double-wall thermal blanket construction consisting of two 2-by-4, 16-inch on-center walls spaced 5 inches apart and filled with 12 inches of open-cell spray foam. The outside walls were sheathed with an oriented strand board (OSB) that is laminated with a wall air barrier that is taped at the seams. The roof water barrier consists of OSB that is laminated with a roof water barrier that is taped and coated at the seams plus and ice-and water-shield at the roof eave and valleys. The vented attic is insulated with 18 inches of blown cellulose on the ceiling deck.
The home’s dry-by-design basement foundation sits on a bed of crushed rock. The basement slab is wrapped in 2 inches of high-efficiency extruded polystyrene (XPS) rigid foam foundation insulation while 3.5 inches (R-20) of closed-cell (high-density) foam is sprayed on the inside of the basement walls. The foundation water barrier includes walls that are damp-proofed on the outside and separated from the footings by a capillary break.
This DOE Zero Energy Ready Home is one of eight high-performance homes built by Transformations Inc. in Devens, Massachusetts, about 50 miles west of Boston.
While most new homes score about 100 in the Home Energy Rating System (HERS) index, and existing homes average 130 or higher, this high-performance home scored a remarkable -21, thanks to the 18-kW solar electric system.
Homeowners of the eight high-performance homes built by Transformations were expected to receive checks of $700 to $1,300 per year as credits for their solar power production.
High-efficiency, ENERGY STAR-rated appliances and water-saving, low-flow fixtures add to water and energy savings in the high-performance homes.
All of the home’s heating and cooling is provided by ultra-efficient (23 SEER; 10.6 HSPF) ductless heat pumps.
“Last year, I got a check from the utility for $700.”
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"In our old house, our heating was oil and pellets. We paid $1,500 a year for oil, $1,000 for pellets, and electricity was $2,400 a year. I don’t have any of those bills now. Last year, I got a check from the utility for $700."
– Transformations homeowner