The U.S. Department of Energy's 2011 Solar Decathlon competition is set to kick off at the National Mall's West Potomac Park in Washington, D.C., in September. The event challenges 20 collegiate teams to design, build, and operate solar-powered houses that are cost-effective, energy-efficient, and attractive and in the lead up, the University of Maryland Solar Decathlon team has unveiled its entry called the WaterShed – a structure designed to capture more than just energy from the sun.

The WaterShedis formed by two rectangular units joined by a central bathroom and is capped by a split butterfly roof that serves the dual purposes of capturing both sunlight and rainwater. A rooftop photovoltaic array harvests enough energy from the sun to power the building all year-round, while the green roof also retains rainwater to cool the house. Water captured from the roof is also used in an interior waterfall to provide humidity control.

"This will be a lot more than a great house – think of it as a mini-ecosystem," said WaterShed's principal investigator, University of Maryland Associate Professor of Architecture Amy Gardner.

In an effort to create a house that has the same effect on the environment as native wetlands the WaterShed's sustainable features extend beyond the structure's walls and are designed to protect and make the most of its Chesapeake Bay location. Constructed wetlands surrounding the building are designed to filter storm water and "greywater," which is a significant source of Chesapeake Bay pollution, while "edible landscapes" create support for community-based agriculture.

University of Maryland President Wallace Loh described WaterShed as "a model for how to live in harmony with the complex ecosystem of the largest estuary in the United States."

Construction of the WaterShed is due to be completed in the fall before it is then disassembled and transported to Washington, D.C. for the final competition in September/October 2011. The WaterShed is the University of Maryland's fourth entry in the Solar Decathlon competition with the University fielding entries in the inaugural 2002 Decathlon and the 2004 and 2007 competitions. In 2007 the University's LEAFHouse placed first in the U.S. and second in the world.