Students show possibilities of a solar lifestyle

The digital display showed that over the previous two days, the pavilion-like structure, designed by architectural and engineering students from Virginia Tech, had drawn about 20 kilowatt-hours from the electric grid. But during the same period, double-sided photovoltaic cells on the roof had pumped about 60 kilowatt-hours back.

“That’s pretty good,” said Mr. Hamilton, who was tweaking the house’s control systems because his firm, Siemens, is a sponsor. “We rode it hard this morning.”

The Virginia Tech team members had been busy with last-minute preparations for the opening of their project, called Lumenhaus, and of the Solar Decathlon, a federal Department of Energy competition to design and build an efficient and livable solar-powered dwelling. The 10-day event includes 20 student teams from universities in the United States, Canada and Europe.

Some groups had been scurrying around even more frantically. Students and faculty advisers from the University of Wisconsin, Milwaukee, were in hard hats, sawing and hammering, and were still working long after the 1 p.m. opening ceremonies. The Virginia Tech house’s net production of energy will be worth some points in the competition. But it and the other entries will not be judged by electrical use alone. There are points to be had for architectural design, engineering skill, comfort and marketability — 10 categories in all.

“The idea is to prove to people that solar works, and you don’t have to give up your lifestyle to use it,” said Richard King, director of the biennial competition for the Energy Department, which gives $100,000 to each team to get the projects started. The event is also meant to get the students to think about solving energy problems in affordable ways — all the projects have to be geared to a specific market, from low to high income.

The houses, which are limited to 800 square feet, are fully outfitted with furniture, appliances and furnishings — even sheets, towels and books. Team members do not live in them, but they have to do household activities like cooking and washing clothes, and are judged on whether their systems can maintain comfortable air temperatures and produce enough hot water. The television has to be left on six hours each day, to demonstrate that there is enough electricity for entertainment.

With the houses lined up in two rows in the shadow of the Washington Monument, the competition resembles a futuristic trailer park. There are innovative materials and designs everywhere — self-adjusting exterior blinds at Team Ontario’s house that can also reflect sunlight into the building; a plastic water wall at the University of Arizona’s entry that absorbs sunlight and gives off heat; and, at the Lumenhaus, movable translucent panels insulated with aerogel, which allow light through.

Solar panels, both photovoltaic and thermal, adorn the roofs. Some are mounted in the conventional way, tilted so that the sunÂ’s rays strike close to perpendicular to improve conversion efficiency. But some have panels flat mounted, or on the sides, like high-tech (and expensive) shingles, or with mechanisms to allow them to be tilted to follow the sun. The competition encourages sustainability, so most of the houses have systems to use rainwater and reuse wash water for plants. Recycled products are found on exteriors (battens made from pressed paper and wood on the University of MinnesotaÂ’s house) and in interiors (cabinet doors made from pressed sorghum straw in Team MissouriÂ’s kitchen).

Many of the interiors are designed to be flexible and adaptable. At the Lumenhaus, for instance, wardrobe cabinets in the center can be slid toward the walls to isolate the bedroom from the living area, and a moveable counter can cover much of the kitchen surfaces or be used as a table.

Mr. Hamilton, the Siemens representative, liked the interior so much that he had an offer for the Virginia Tech students. “I told these guys, I’d live in this house,” he said.