At a small construction site tucked between an ice skating rink and an office building, students, professors and contractors sing along to country music as they put the finishing touches on two small houses joined in the middle by a manmade wetland.

The University of Maryland students are building WaterShed, the school's entry in the 2011 Solar Decathlon. They are competing against 19 other teams from around the world, including China and Australia.

After months of construction and more than a year of design and planning, the house — powered entirely by solar energy, but with a focus on water conservation and reuse — is nearing completion. It consists of two modules, one a work space, the other residential, which are joined by a "constructed wetland" that will filter water used by the tenants and save it to be reused.

Though all houses created for the competition must be entirely solar-powered, students at the University of Maryland decided that an emphasis on water conservation would be especially appropriate because they are close to the Chesapeake Bay.

The black basin that runs underneath the house holds a wetland for filtering water used inside each module. The middle portion of WaterShed features floor-to-ceiling glass windows, allowing residents to see exactly how much water they use as it runs into the wetland below.

"You literally see where your water ends up," said Veronika Zhiteneva, a 19-year-old environmental science major. "You're conscious of your water."

Water that will be recycled comes from bathroom sinks, showers and the washing machine. This water will pass through the wetlands, stocked with a variety of plants native to the bay's watershed.

"They serve as a coffee filter and a sponge," Zhiteneva said.

The house features a gutter system that directs storm runoff into the wetlands. This prevents flash flooding and provides extra filtration, Zhiteneva said.

Newton Gorrell, a 27-year-old architecture student in the graduate program, said the roof has 36 solar panels. It also has a "green roof" that will contain plants that will help reduce water runoff after a storm.

WaterShed also features a set of glass tubes filled with a liquid called glycol which, when struck by the rays of the sun, can heat up to 180 degrees. This heat is then transferred to a hot-water heater which warms all of the water used by the house,

The students have taken the goals of the competition a step further by trying to create more energy than it uses. This excess energy can then be sent back out to the power grid for use by other homes.

The "ultimate goal is to produce more power than you use," said David Daily, a 21-year-old electrical engineering student. "Construction of our house is done in a way that maximizes the efficiency of everything."

Amy Gardner, a professor of architecture at University of Maryland and a mentor for the project, said the WaterShed is "much more … complete and holistic" than it's 2007 entry. For her, the project is more than a competition — she wants the house to tell a story to promote water conservation.

"All teams are concerned about is whether they're going to finish on time," Gardner said. "We aim to win, but we really want to tell our story."

The project costs between $800,000 and $1 million, mainly because it's a prototype. If WaterShed were to become a commercially built house, it would cost about $300,000.

Solar Decathlon entries can be viewed from Sept. 23 to Oct. 2 at the National Mall's West Potomac Park in Washington. This is the fourth time that the university has competed in the solar decathlon. The school placed first in the United States in 2007 for its "LeafHouse."

xcxjbaughman@baltsun.com

Earlier versions of this story misspelled the name of David Daily, and gave an incomplete account of how the University of Maryland finished in a 2007 competition.