Breakthough Construction: Passive Homes Go Prefab

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When Elizabeth Scott ordered a new energy-efficient home for her property in rural Guilderland, New York, a factory in Searsmont, Maine that manufactures passive house components  went to work.

Ecocor High Performance Buildings, a construction firm that designs, manufacturers, delivers and assembles passive house parts – certified by the Passive House Institute in Darmstadt, Germany – created the prefabricated sections for Scott’s new residence, according to a March 24 report by the Albany, New York, Times Union.

A team of workers unloaded the wall and roof sections on a Wednesday in early March, hoisting them into place on the previously poured foundation. Three days later, the house was nearly assembled, and finishing work, including plumbing and electrical systems, had begun.

Construction costs were about $237 per square foot., the Times-Union reported. But the house is projected to cut energy consumption by 80 to 90 percent, with annual heating and cooling costs falling to $200 a year.

Passive houses are ultra-low energy buildings that require minimal power for heating and cooling. They are not just residential: Office buildings, schools, and even supermarkets have been built to the passive house standard.

Scott said she had been interested in buying a highly energy efficient home for some time, but had waited until a prefab version was available. Enter Milford, Pennsylvania- based passive house architect Richard Pedranti and Chris Corson, founder and technical director of Ecocor.

"We started doing prefab passive house panels in 2012," Corson told the local news outlet. "They were all custom. Now we can bring a platform of homes people can customize."

The Guilderland house was the first completely prefab house the partnership between Pedranti and Ecocor has produced. Pedranti collaborated with Scott over a six-week period, customizing her model home. The computerized design provided instructions to the automated production line, where programmed saws cut pieces to be assembled and finished at the factory — a four- to six-week process — before the 6,200 components were ready to be loaded onto trucks for delivery.

The panels in the passive house that Scott will live in are packed with cellulose insulation, wrapped in a Gore-Tex "jacket," with 18.5-inch-thick walls and efficient windows.

The completed building is airtight. A heat recovery ventilator brings in fresh air while transferring the heat from the air being exhausted.

Pedranti and Ecocor now are marketing a dozen different models, ranging from a one-bedroom/one-bath model for $152,000; to a three-bedroom/two and one-half bath model, with 1,932 square feet of interior space, for $496,000. Corson said he expects prices will come down as more of the houses are produced.

Scott considered retrofitting an existing house to achieve the energy efficiency she was seeking but decided against it."There's a lot of things that (can) go wrong," she told the newspaper. "It's hard to retrofit an old house." 

Environment + Energy Leader