©2013 Green Building Advisor. From The Taunton Press, Inc., publisher of Fine Homebuilding Magazine.
The designers of a 1,700 square-foot net-zero-energy demonstration home in Irvine, California, claim that a similar home can be built by virtually anyone for less than $150 per sq. ft., a figure that’s price-competitive with conventional homes in this market.
The developers of the home — Southern California Edison and Green Homebuilder magazine — call the three-bedroom, two-bath model home “the ABC (Affordable, Buildable, and Certified) Green Home .” The home’s energy features should reduce its estimated monthly utility bills by $150 to $200 compared to a similarly sized conventionally built home.
John Morton, project manager for Southern California Edison, says that the ABC home’s energy-saving strategies are mainstream and so they shouldn’t scare off buyers who might be leery of unfamiliar technology. The mild climate means the house can achieve net-zero status with 3 1/2 inches of Demilec closed-cell spray foam in the walls (in addition to 2 inches of EPS  on the exterior side of the wall sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. ) and 5 1/2 inches of closed-cell spray foam in the ceiling. The roof deck is insulated to keep the ductwork within the conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort. .
The water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (WRB) installed on the walls is a vapor-permeable membrane (Henry BlueSkin VP ).
The house was built in conjunction with North Orange County Regional Occupational Program. Students in seven high-school construction classes designed and built the wall panels as part of their training. The panel sections were then brought to the site (in Irvine’s Great Park), where they were assembled by a contractor. The partners spent $204,000 to build the house — about $120 per sq. ft., a figure they say could be lower with a large builder’s efficiency of scale factored in.
For a virtual tour of the ABC Green Home, click here .
The house will be on display Mondays, Wednesdays, Fridays, and weekends from 9 a.m. to 4 p.m. until October 2013. At that time, the house will be separated from its slab foundation and donated to Habitat for Humanity, which will move it to a new site. The next ABC home will be a similarly sized two-story model. California is trying to make all new homes net-zero by the year 2020.