• Team WaterShed's Solar Decathlon entry has a split-butterfly roof well-suited for capturing and using sunlight and rainwater. The two main parts of the house are connected by a third, smaller module that houses the bathroom. By reusing greywater on site for irrigation, the team estimates that the house will cut the amount of water sent to sewage treatment plants by half.

    Credit: Illustration: Leah Davies

    Team WaterShed's Solar Decathlon entry has a split-butterfly roof well-suited for capturing and using sunlight and rainwater. The two main parts of the house are connected by a third, smaller module that houses the bathroom. By reusing greywater on site for irrigation, the team estimates that the house will cut the amount of water sent to sewage treatment plants by half.

Every two years, university teams gather in Washington, D.C., to compete in the Department of Energy’s Solar Decathlon, a public showcase of cutting-edge innovation in sustainable housing. The 19 homes in the 2011 Solar Decathlon combined rooftop-mounted and building-integrated photovolatics and solar thermal systems with passive solar design, energy-efficient building envelopes and products, and high-performance construction.

The winning team from the University of Maryland went beyond energy issues to focus on water conservation. Inspired by the Chesapeake Bay, Team WaterShed’s holistic approach included an innovative man-made wetland biofiltration system to capture, recycle, and store stormwater and greywater.

Rainwater flows from the roof along a central axis to a consolidated mechanical core, where it mixes with greywater from the shower, clothes washer, and dishwasher. From there, the water flows into modular planters of native grasses and indigenous plants located under the bathroom and along the decks. Made up of hardy water lily, swamp hibiscus, blue flag iris, and other low-maintenance plants, these “constructed wetlands” break down nutrients and remove pathogens and pollutants such as soap from the greywater, helping to keep the stored water clean.

The house also features a green roof, an optimally sized photovoltaic array, and a liquid desiccant waterfall that provides high-efficiency humidity control.