In the fall of 2011, 19 collegiate teams met in Washington, D.C. to showcase solar-powered houses that they designed and built for the fifth biennial Solar Decathlon. The competition, sponsored by the U.S. Department of Energy, included teams from the United States, China, New Zealand, Belgium, and Canada. Teams were challenged to build net-zero energy homes, which produce as much energy as they use over the course of a year. In addition to being assessed on energy production and efficiency, homes were judged on affordability, consumer appeal, and design.