A Watershed Moment

Held every other year on the National Mall in Washington D.C., the U.S. Department of Energy Solar Decathlon challenges collegiate teams from the United States and other countries to design, build, and operate solar-powered houses that are cost-effective, energy efficient, and attractive. In this article, members of the University of Maryland's team describe their 2011 contest-winning house. They designed a net-zero-energy house powered by a photovoltaic array, supplied with hot water by an evacuated-tube solar-thermal system, and surrounded by a wetland that collects water from two inward-sloping roofs and filters gray water from inside. The 876-sq.-ft. house, which beat 18 other entries to take home the top prize, has a 13-in.-thick envelope with R-44 walls, an R-48 roof, and R-33 floors. A sidebar describes the contest's 10 events: affordability, architecture, comfort zone, engineering, communications, appliances, home entertainment, hot water, energy balance, market appeal.