Right now, the National Mall in Washington, D.C. is packed with the houses of the future. Teams from colleges and universities around the globe came to the city with the most efficient homes they could dream up to take part in the Solar Decathlon, a design competition sponsored the Department of Energy.The houses compete in ten areas (that's what makes it a decathlon) ranging from "energy balance" to "lighting." So far the team from Santa Clara University and the California College of Arts won the "architecture" contest and University of Louisiana at Lafayette won the "market viability" contest (Treehugger has video of both).For more, check out Inhabitat's running coverage of the event, TreehuggerTV, and the Department of Energy's awesome Flickr set.Energy secretary Steven Chu has been hanging around the event checking out the buildings and making $87 million announcements. The buildings will be open for the public to tour come Friday.Photos from the DoE Flickr set (cc)