Near-net-zero-energy performance in a new home is unusual enough in most communities to attract free publicity. A recent example: a 2,507-sq.-ft. home in southeast Abilene, Texas, that is constructed with superior exterior wall insulation, airtightness, and HVAC, careful solar orientation and well designed roof overhangs, and a 20-panel solar array.

The local newspaper, the Reporter-News, highlighted several features of the recently completed house, which offers four bedrooms, three baths, and a three-car garage, and sits on two acres of land. The main focus of the story, though, was on the building’s green amenities, including exterior walls with 5 1/2 in. of Demilec Agribalance spray foam insulation (yielding R-27 thermal resistance); 7 in. of spray foam in the roof deck (R-33); a reflective, standing-seam metal roof; a conditioned attic with an R-33 deck; a rainwater collection system; and 4 kW of power capacity from the solar installation.

Reckoning with winter cold and summer sun

William Peck, whose architecture firm designed the house – and more than a dozen near-NZE homes in other parts of the state – said it is equipped with Pella double-glazed vinyl windows with a .29 solar heat gain coefficient. He also noted, though, that all of the critical windows are shaded.

And because winters in central Texas can include freezing temperatures and snow as well as mild days, the house features a high-efficiency pellet stove (capable of heating 1,500 sq. ft. of the house), and, to manage the summer heat, a 16 SEER HVAC system with timed exhaust, and variable-speed air handlers.

Constructed by Abilene-based Sela Builders for about $120 a square foot (versus traditional-construction costs of about $88), the house also features two air-source heat pumps for hot water. The local power company, Taylor Power Cooperative, will be monitoring the home’s energy performance, the company’s director of business development, James McKee, told the Reporter-News. “We’re seeing this house as a bit of a test tube baby for us,” he said. “We’ll be watching very closely and gathering data for future projects.”

At this point, Peck noted, the house, which is listed for $375,000, is considered “net-zero-energy-capable,” but could easily achieve NZE performance should its eventual owners decide to slightly expand the solar installation. A year of monitoring by Taylor Power should provide enough data to determine how much, if any, system expansion might be needed to reach zero.