Both a laboratory and a house, the residential test facility at the National Institute of Standards and Technology’s (NIST) Maryland campus features a well-insulated building shell, energy-efficient appliances, solar water heating, and a solar photovoltaic system.

The house was designed by Westford, Mass.–based Building Science Corp. to demonstrate net-zero capabilities, test advanced technologies, quantify energy use, and compare installed use with controlled use. Now open for two years, researchers found that it operated even more efficiently in its second year, thanks to changes they made to its ventilation and temperature control systems.

On top of eliminating an annual electricity bill of about $3,670—the average for a similarly-sized home in Montgomery County, Md.—the 2,139-kilowatt-hour energy surplus garnered a refund check of about $80 from the local utility. From Feb. 1, 2015, to Jan. 31, 2016, the two-story, four-bedroom house's rooftop solar power system generated a total of 13,717 kilowatt hours of electricity—equivalent to the energy generated by burning more than seven tons of coal or about 1,000 gallons of oil.

The energy surplus jumped 1,655 kilowatt hours over the previous test year. More than 90 percent of this increase stems from reduced energy use, achieved without sacrificing indoor comfort. A slight gain in energy generated by the photovoltaic solar panels—about 140 kilowatt hours—accounts for the remainder.

Read more >