Washington, D.C., is known more for filibusters and less for innovative design. For one rain-soaked week last fall, however, innovation was the theme when 18 university teams converged on the city for the Solar Decathlon, a biennial event in which students compete to see who can design, build, and operate the most energy-efficient solar-powered house.
"The technology is fantastic, and it is events like the Solar Decathlon that bring it into the public eye," says John J. Loyer, a construction, codes, and standards specialist at the NAHB, one of the sponsors.
The University of Colorado won the overall event, but every team was successful in demonstrating that solar energy could be the bright spot in an energy future that is starting to look dim.
Solar power, which involves using photovoltaic panels to convert sunlight into energy, is not a new idea but it hasn't been a particularly cost-effective one either. Although clean and renewable, the technology is costly and panels have been rather inefficient compared to other sources of energy. As a result, solar usage is non-existent in this country, with the share of electricity produced by solar cell technology less than 1 percent.
But sun power is gaining momentum due to incentives, tax breaks, and the rising cost of fossil fuels. Moreover, improved technology is creating a new generation of solar cells that are more efficient and cheaper. As a result, solar installations increased 27 percent in 2004, say industry officials.
But the Solar Decathlon was more than just energy; it was an exercise in how students could gracefully integrate the technology into the architecture. The University of Maryland, for example, focused on designing a house with broad appeal.
"We made a strong effort to create a warm and comfortable home that would appeal to a wide audience," says Maryland student Tom Serra, construction group leader on the house. "The surfaces and finishes are similar to what you would see in the average American home."
Energy came from the 51 panels integrated into the dwelling's curved roof. Radiant-heated concrete floors, natural fiber insulation, and passive solar heating made the interior comfortable, while good-looking certified wood, bamboo, and recycled glass made it attractive.
The student-built structure from Virginia Polytechnic Institute and State University concentrated on a more cutting-edge design. "The architecture enhances the engineering systems," says master's candidate Brett Moss.
A butterfly roof screens the panels from the curb, while its center drains rain into a cistern for gray water use. The house has a ghostlike radiance from translucent polycarbonate walls that bring in light while offering privacy. Instead of traditional insulation, the two layers of polycarbonate were injected with an aerogel insulation to deliver an energy-efficient R-value of 22.
Meanwhile, California Polytechnic State University pursued a strategy that builds on prefabrication. Built with 6-inch structural insulated panels, the house has R-23 walls and R-37 roof and floors. "We have reduced a lot of our energy needs just by having a tight envelope," says Nicholas Holmes, a fifth-year architecture student. A breathable housewrap lets moisture out but not in and sleek wood-resin panels create a low-maintenance shell.
Rhode Island School of Design also focused on prefab construction, but the students "envision this as a modular product that can be used in multiples in an urban setting," says design team member Molly Wheelock, a recent graduate of the architecture school.
Despite the college students' best efforts to showcase its potential, solar energy still has obstacles to overcome. For one, it has high upfront costs. "If you want 3 kilowatts for your house it is going to cost you anywhere from $25,000 to $30,000," says Richard King, director of the Solar Decathlon at the U.S. Department of Energy, one of the event sponsors. Another barrier is aesthetics: "A lot of people don't want these contraptions on their roofs," King notes.
But the event proved the panels can be successfully integrated into the roof. "If you design the house from the ground up and the solar is incorporated in it, the aesthetics are better," King says, adding that rolling the system into a mortgage is a wise idea. "You might be paying $30 more per month for your solar system, but you are saving $70 a month."
"In order to fully support it, the NAHB would like to see it become much more cost effective and affordable," contends Loyer. But if "affordability" can be achieved, solar could play a significant role in America's future housing and energy needs, he adds.
Virginia Polytechnic Institute and State University. The roughly 800-square-foot house used operable windows and shading devices rather than mechanical equipment for heating, cooling, and lighting. Clerestory windows permit daylight, while movable dampers in the walls bring in fresh air. Motorized shades adjust temperature in the wall cavity during the day and provide visual privacy at night. A stressed-skin inverted roof conceals the solar panels and drains rain into a cistern for gray water use. 540-231-6000. www.vt.edu.
University of Maryland. This college team focused on designing a house with broad appeal. The surfaces and finishes are similar to what you would see in the average American home, but it's also highly efficient. Energy comes from the 51 panels integrated into the curved roof. Radiant-heated concrete floors, natural fiber insulation, and passive solar heating make the interior comfortable, while certified wood, bamboo, and recycled glass make it attractive. 301-405-1000. www.umd.edu.
University of Colorado. The winning team was eager to unveil the innovative, bio-based structural insulated panels, called Bio-SIPs, used for the walls. Julee Herdt, one of the team's faculty advisers, developed the Bio-SIP with the help of researchers at the U.S. Department of Agriculture. It meets all building code requirements and is patented. The Bio-SIPs and high-performance window glazings contribute to the home's energy efficiency. So does the integrated radiant solar thermal system used for space and water heating. The team also carefully selected a rooftop PV system and building-integrated PV awnings, which provide shade as well as electricity. 303-492-1411. www.colorado.edu.
Best in Show
Although the University of Colorado won the overall competition, Virginia Polytechnic Institute and State University took first place in the architecture category. "Everything about this house is wonderful," says renowned architect Sarah Susanka, one of the judges. "It took my breath away."
Virginia Tech designed the roughly 800-square-foot house to use operable windows and shading devices rather than mechanical equipment for heating, cooling, and lighting. As such, the south, east, and west walls were constructed of translucent polycarbonate panels filled with aerogel insulation. Clerestory windows permit daylight, while movable dampers in the walls bring in fresh air.
Motorized shades adjust temperature in the wall cavity during the day and provide visual privacy at night. A stressed-skin inverted roof conceals the solar panels and drains rain into a cistern for gray water use.
California Polytechnic State University, which placed second in this category, designed its house with structural insulated panels and colored fiber-resin cladding. Architecture student Nicholas Holmes says the team kept the structure narrow for easy transport and added the solar panels, awnings, and rooftop deck on site. The judges called the exterior "beautiful" and the interior "elegant."
–Nigel F. Maynard