A Duel in the Sun

Environmental matters governed Cornell's choice of materials. The porch floor is a composite of wood and recycled plastic fibers. The ceiling wood was made from an old silo. The siding is sustainably harvested white cedar.

The secret to success in the decathlon isn't just the energy generated by solar panels; it's finding ways to slash energy use. The Cornell kitchen, for example, features refrigerators that open like drawers so that cold air, which falls, does not escape easily when the door is opened. At the University of Maryland's LEAFHouse -- "A leaf is the ultimate solar collector," said Brittany Williams, an architecture major -- a wall of plants on the south side provides a sunshield and filters water for reuse. Texas A&M has quadruple-pane, argon-filled windows. Fluorescent bulbs and LEDs are standard.

Turning an appliance into decoration, an indoor waterfall doubles as a dehumidifier at the U-Md. house. About 30 percent of the energy used by home air conditioning goes to reducing humidity. The waterfall uses a mixture of calcium chloride, an absorbent salt, to suck moisture from the air. If any of the liquid mix spills, it absorbs humidity and the puddle grows. The liquid tumbles down a clear decorative panel with an opening for air, then drains to a device outside where the excess moisture evaporates before the remaining liquid is pumped back into the house.

Some homes have frivolous touches. The University of Texas home siphons excess heat into a hot tub. The team sheathed the home in aluminum bus siding plastered with a blown up image of a cactus flower.

Foreign universities are also competing. A handsome structure with louvers made of oak and photovoltaic cells has been built by the Darmstadt University of Technology. It features sleek appliances from Germany, where energy efficiency and renewable energy are higher priorities than in the United States.

U.S. use of solar remains tiny despite generous subsidies and industry growth rates approaching 40 percent a year. Climate change concerns are driving new initiatives to limit the use of coal, which accounts for half of the country's electricity. Since the last solar decathlon, more states have tried to kick-start solar construction. California has begun an 11-year, $3.35 billion subsidy program aimed at installing solar panels on 1 million homes, and its utilities are planning large-scale solar generating installations.

Climate change ironies about the decathlon weren't lost on the students. Colorado used three flatbed diesel trucks to get its home to the Mall. Cornell's trucks had to follow a roundabout route to take bridges strong enough to bear the weight of the equipment, turning a 350-mile trip into a 600-mile one and adding to the fuel burned to get to the District.

"Hopefully, the impact we have by being on the National Mall will offset the diesel it took to get here," said Chad Corbin, a graduate student in engineering at the University of Colorado.

The Solar Decathlon is open to the public until Oct. 20, from 11 a.m. to 3 p.m. weekdays and from 10 a.m. to 5 p.m. weekends. It is closed Wednesday for judging. More information is available athttp://www.solardecathlon.org.