By today’s standards, it’s a modest house: three bedrooms, single level, architecturally suited to the late-1960s-era neighborhood in which it sits. Even after just a few months, and thanks in part to the preservation of the mature landscape around it, neighbors tend to forget what the previous house on the lot looked like—a sure sign that the new dwelling is fitting in just fine.
But unlike any other house in Lewisville, Texas, and only a few nationwide, this 2,500-square-foot home is designed and built to achieve net-zero energy consumption. An array of 42 photovoltaic panels along the south-facing roof, hidden from street view, is set to gather and convert enough solar power into electricity to equally offset even the most extreme cooling loads and the rest of the home’s power needs, with a little extra capacity built in to earn some extra net-metering credits from the local utility. Ideally, the only line item on the homeowner’s monthly energy bill will be the service charge to keep the account open.
Still, the 600-square-foot PV array is only the mechanism for balancing the home’s power draw, not its defining feature. “This is a high-performance house with some green products in it,” says Chris Miles, a principal with GreenCraft Builders in Lewisville and a student of building science. “You don’t need green products for a house to perform well, but homeowners like it and I enjoy integrating them into the houses we build.”
That mix of passion and market savvy has enabled Miles to build seven homes to LEED-Gold or higher certification. This latest one reaches the Platinum level of that rating system (with a HERS score of 1, among other feats) and meets the standards for the Energy Star Qualified Homes and Green Built Texas programs (the latter of which is awarded automatically to homes that achieve at least LEED for Homes Silver); certification under the ANSI National Green Building Standard is pending.
Even after collecting all that hardware, the builder is only impressed with how his homes actually perform. That’s why, after discovering and diving head first into building science five years ago, Miles became a Building America builder, dedicated to reducing the carbon footprint of the built world under the guidelines of that Department of Energy program. “They come in and test for everything,” he says of the Building America verifiers who use homes like his to expand their database of real-world applications and results. “It’s the only way we really know how to improve what we do.”
That testing came in handy when Miles and architect Bill Peck considered the challenge of a net-zero house. “There’s no way of knowing if you have enough PVs unless you know how much energy the house will require,” a calculation based on its design, construction, and everyday occupant behavior, says Miles.
Results from monitoring the energy demand of a 2,400-square-foot, single-story, high-performance house Miles built two years ago, his first show home with GreenCraft, proved invaluable for this latest project, helping drive the home’s orientation and layout to accommodate an array that would generate 1,000 kWh of electricity to offset an anticipated draw of 805 kWh a year. “We didn’t have to guess on this one,” says the builder.