A team from the University of Maryland finished second. Visitors touring their house were attracted by an indoor waterfall that provided a novel way to use a liquid desiccant to soak up humidity so less energy was needed for cooling.
''The concept is sound,'' said Brian Borak, 25, a chemistry major, adding that it's been used in industrial applications, but never in a residential situation. The university is thinking of filing a patent.
Renewable energy sources — mostly wind turbines — account for a little more than 2 percent of electricity production. A very small percentage comes from solar, or photovoltaic, cells such as those used in the houses on the Mall, according the Energy Department.
But in the two years since the last Solar Decathlon, the competing house designs have become more mainstream, according to judges and participants. For the first time a category of ''market appeal'' was added to the criteria on which teams were judged. While the prototype homes were said to cost $500,000 or more to design, ship and erect, they also contained many features that are commercially available, according to competition organizers.
''In 2005 (the houses) were experiments. This year they're not. ... They're an example of what can be done,'' said Bob Burt, a building consultant who was one of the judges ranking the homes on market appeal. ''There are a couple of houses that when I first walked in I said, 'Yeah, I could live here.'''
Leo and Darlene Michitsch, visiting from Cleveland, saw in the homes not only a glimpse into the future, but also a hint of something here today.
''We have an interest in putting improvements into our home,'' said Darlene, who teaches art at a university. The couple had already visited several of the houses and ''we're learning a lot,'' she said.
Lori Johnson, of Lakewood, Colo., said the modernistic design of most of the houses ''is not my style'' but they had piqued her interest in solar.
''We've talked about the idea of (using) more solar in our home,'' she said, noting that Colorado had ideal conditions for the technology.
''These houses, generally speaking, are much more real, much more part of the next generation of something that is actually going to be built,'' said Bodman, the energy secretary, whose department sponsored the competition.
The winning German entry was cited not only for its solar technology and energy saving, but for its efficient use of space and multifunction design. Its solar cell-imbedded louvers were a source of both shade and energy. The furniture was made so it could be lowered and hidden beneath the floor when not in use to make rooms multifunctional.
The large crowds and high level of interest surprised many of the students. ''We're also surprised that they like our strange ideas,'' said Andreas Pilot, 28, an architect student and member of the German team.