This year's Solar Decathlon competition combines traditional architecture with cutting-edge building materials and the latest high-tech gadgetry in a village of net zero-energy homes.
The Department of Energy-sponsored Solar Decathlon is a biennial competition among 19 university student teams to build homes entirely powered by solar energy. The houses are shipped in pieces to Washington, D.C., where they are assembled and put on display for 10 days to the general public. (See coverage from 2009 and 2007.)
After a ribbon-cutting of the "solar village" yesterday, teams are showcasing the projects to the visiting public and to judges who will rank the homes based on aesthetics, engineering, cost, and efficiency. This year has a sharper focus on practicality by limiting construction costs to $250,000.
The houses on display this year at the National Mall's West Potomac Park recall many of the same design principles seen in past years. Many teams' buildings use a modular design for easier construction and all of them have the latest in efficient appliances, LED lights, and, of course, rooftop solar panels.
With some notable exceptions, many student teams this year chose an architectural look to fit into their respective regions, such as the Solar Homestead from Appalachia State University and New England Farm from Middlebury College. On the technology side, there's plenty of home automation and the use of phase-change materials, or gels that turn to liquid to store solar energy for hours.
"There are a lot of traditional designs and part of that is that each team designs for their environment," said Lanna Semel, a member of the team from Southern California Institute of Architecture and California Institute of Technology. "It's very evident that they all come from different regions in the U.S. and around the world."
Heavy insulation and an air-tight building envelope are de rigueur for these homes as better efficiency lowers the overall energy load, which is only supplied by solar photovoltaic and solar hot-water panels. The team from Parsons New School for Design and Stevens Institute of Technology built a Passive House, a German standard that requires meeting specific energy performance characteristics. Since they are so tight, homes have mechanical air-ventilation systems and take advantage of natural air flows to ensure a steady flow of fresh air.
Water conservation is another common feature, with many homes capturing rainwater in a cistern and using pumps to water landscaping or vegetable gardens.
Increasingly, there are off-the-shelf home automation systems that let people control heating, cooling, lighting, and house electronics from a tablet, TV, or other connected device. In a clever hack, the team from southern California integrated the Control4 home automation system with Microsoft's Xbox Kinect so occupants wave their hands to turn off lights or control the house thermostat.
The southern California team's architecture is an eye-grabber as well. Eschewing traditional design, it built an avant-garde house that more resembles Apollo-era space capsules than a typical American home, complete with a vinyl blanket covering a layer of insulation around the building's exterior.
For the past two Solar Decathlons in D.C., the Technische Universitat team from Darmstadt, Germany, came away with the first prize. But Germany's high-tech home came in with a price tag of near $800,000, more than three times higher than the $250,000 limit this year.
Regardless of which team wins this year, the Solar Decathlon is exciting because people can see the possibilities of energy efficient buildings and the enthusiasm of students for sustainable building design.
Each year, the products at the Solar Decathlon become more accessible and more mainstream--everything from LED lights to solar panels. Ultimately, though, these houses are about design and how the right building techniques can bring out the potential in green building technology.