The net-zero energy test house at the National Institute of Standards and Technology (NIST) in suburban Washington, D.C., not only absorbed winter’s best shot, it also came out on top, reaching its one-year anniversary on July 1, 2014, with enough surplus energy to power an electric car for about 1,440 miles (an electric car gets 2.94 miles per kilowatt hour, according to the U.S. Environmental Protection Agency).

Despite five months of below-average temperatures and twice the normal amount of snowfall, NIST’s Net-Zero Energy Residential Test Facility (NZERTF) ended its one-year test run with 491 kilowatt hours of extra energy. Instead of paying almost $4,400 for electricity—the estimated average annual bill for a comparable modern home in Maryland—the virtual family of four residing in the all-electric test house actually earned a credit by exporting the surplus energy to the local utility.

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