Tuesday, December 13, 2011

Saving Energy in Affordable Homes: $300 - $500/Year

About a year ago, Rural Development, Inc. (RDI) completed construction of the 20-home project “Wisdom Way Solar Village” in Greenfield, MA. The project is a mix of affordable and market-rate homes, and it was RDI’s latest effort in approaching “zero energy” homes. Through the U.S. Department of Energy’s Building America program, Steve Winter Associates (SWA) provided support during the design and construction....

The home’s envelopes are ... efficient with R-40 walls, triple-pane windows, and R-50 attic insulation.... With both solar electric and solar water heating systems, SWA estimated total gas and electricity bills for the homes would be less than $500 per year. Now, after several homes have been occupied for a full year or more, the predictions look quite accurate.

Average annual gas and electric bills for eight homes were $401 (ranging from $324 to $485 — including service charges of $140 per year). Because of the PV systems and efficient use of electricity, most residents actually had a net credit from the electric utility over the past year.

Overall, this development is an excellent example of nearing “zero energy” in homes with good design and simple, cost-effective systems.

At http://www.greenbuildingadvisor.com/blogs/dept/green-building-news/deep-energy-savings-wisdom-way-solar-village Richard Defendorf noted ... exterior walls are insulated to R-40 with 12 in. of blown-in cellulose, the roof to R-52 with 14 in. of cellulose, and the floor to R-38 with 11 in. of cellulose. Triple-pane windows were used throughout. Heat is provided by a Monitor Products GFI1800 gas space heater located in the central area of the first floor of each house. Each home also is equipped with an exhaust-only ventilation system and an additional interior fan that draws air from the ceiling of the first floor and redistributes it to each bedroom.... The airtight and well-insulated building envelopes keep the design heat loads of the houses at less than 12,000 Btu per hour. The gas heater capacity ranges from 10,200 Btu on low fire to 16,000 Btu on high fire. Prices for the houses ranged from $110,000 (for a two-bedroom) to $170,000 (four-bedroom) in the low-income category and $150,000 to $210,000 for moderate-income buyers. A two-bedroom market rate home was priced at $210,000 and a three-bedroom was listed at $240,000.

For more information contact Robb Aldrich at raldrich@swinter.com or visit http://www.ruraldevelopmentinc.org/index-wwsv.htm.

Winter Green http://www.swinter.com/resources-newsletters-wintergreen.htm
Steven Winter Associates www.SWinter.com
Volume 12, Issue 6; June, 2011

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