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In April of 2009, searching for a way to showcase sustainable housing, the Commonwealth’s MassDevelopment put out a Request For Qualifications for developer/builders to design and build single family and multi-family homes at its Devens, Massachusetts residential community. The purpose of the project was "to provide a replicable example of current and innovative sustainable building practices that are practical for Massachusetts homes. In keeping with the Governor's stated goal of moving toward zero net energy development, a goal of the project is to provide a forum for development of zero net energy, or near zero net energy, moderately-priced housing".
Transformations, Inc. was chosen to build the single family project with a total of 8 homes. In the summer of 2011 we began construction on the first two homes. The first home was sold by October. By the following October in 2012 all of the homes were either sold or under agreement. We had planned on a 3.5 year build out. The combination of zero energy homes and the great Harvard public schools seemed to be a potent combination.
The final HERS indexes have ranged from HERS 6 to -37. This home represents one of over a 100 zero energy attainable homes in the Transformations development and building pipeline—a sure sign of replicability in the Northeast!
The home starts with a double studded frame wall that is 12 inches thick for a R45.6 cavity insulation level. The attic has 18" of cellulose (R-63), the basement walls have 3 1/2 inches of closed cell foam (R-20), the basement slab and slab edge has 2" of rigid (R-10) and the windows are triple pane (R-5). The super insulated shell allows for a simple Mitsubishi mini split of each of the two floors. And first floor master bedroom. The hot water heater is a 98% efficient Navien unit. The flat portion of the roof faces towards the South and has a 18.33 kW PV system installed on it. After accounting for propane use for hot water, the homes net positive energy production for the year was 10 kWh.
The Devens project has been a resounding success on many levels. These homes met the goals of the MassDevelopment program. They sponsored two zero energy home workshops to help get the word out to other builders and developers. The Department Of Energy extended the Building America Program for Building Science Corporation to continue our work together. Transformations was pleased with another model community designed and built to advance energy efficient construction in the Northeast.
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Four people occupy the residence for 365 days/year
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2" Rigid
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2" Rigid
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3.5" closed cell foam
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12" open cell foam, R-45.6 cavity
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18" cellulose
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