Illinois places second in Solar Decathlon

By Drs. Robert & Sonia Vogl

President and Vice President

Illinois Renewable Energy Association

For three weeks in October, the U.S. Department of Energy hosted a competition between 20 college and university teams that designed, built and operated energy-efficient solar-powered homes. Students raised funds, collected materials, worked with contractors and designed and built homes at their campuses. The homes were deconstructed, taken to Washington, D.C., reconstructed and judged in 10 contests. They are displayed in a centralized area open for public viewing. After the event, they are taken down and shipped back home.

The 10 contests cover architecture, marketability, engineering, lighting, communication, comfort, hot water, appliances, home entrainment and net metering. Judges assign scores for each contest that are summed to provide an overall score. The winner was Germany, followed by Illinois and California.

The intent of the international competition is to bring attention to energy and illustrate the contributions made by efficiency and renewable energy.

The contest encourages a whole-building design approach in which all components and systems interact. It involves students from different academic backgrounds, such as engineering and architecture, working together. It demonstrates the potential of Zero Energy Homes.

The winning home was designed and built by German students. Their philosophy was to use as many new technologies as available. The two-story, cube-shaped building maximizes the production of electricity from solar panels. The 11.1-kilowatt array—consisting of 40 single crystalline, roof-mounted panels and 250 thin-film copper indium gallium diselenide panels on exterior walls—produces twice as much solar electricity as the building uses.

The envelope consists of custom-made, vacuum-insulated panels and energy-efficient windows with automated louver coverings. Phase change materials, which absorb solar energy and slowly release it in the evening, are placed in both walls and ceilings. A boiler integrated into a heat pump system heats and cools the home and provides domestic hot water.

The second-place entry from the University of Illinois, known as the Cable Home, produces up to four times the amount of energy as consumed. It features a gable roof line common to Midwestern agricultural areas illustrating how new technologies and traditional building styles can be united. It contains a low energy-consuming stove, dishwasher and refrigerator. It was designed to consume 90 percent less energy than a traditionally-constructed, similar-sized home. The students are working with a modular home builder in an effort to gain marketplace acceptance.

Minnesota, Iowa and Wisconsin had entries as well. Minnesota’s also featured a gabled roof line reflecting traditional homes of the Midwest. The home captures as much solar energy from passive features as possible for cold weather comfort. Solar energy heats water for home heating and domestic water. In summer, the system drives moisture from a desiccant, removing excessive humidity, cooling the home. Roof insulation reaches R70, while wall insulation is R50. Windows are triple-paned, low-e, filled with gas and fitted with insulating shades.

The Iowa State University entry, Interlock House, was designed with senior citizens in mind and is intended to fit into an existing community. It features an enclosed sun porch on the south with glass walls trademarked as NanaWalls, which slide open in warm weather to increase air flow.

The University of Wisconsin-Milwaukee home, Meltwater: A Sand County Solar House, features a butterfly roof that channels water into a cistern to water yard plants. Many of the materials were left from constructing the Aldo Leopold Foundation Headquarters. The house uses both a solar electric and solar hot water system.

Elements of other homes are eye-catching. One built by Spanish students features an inverted glass pyramid on which both a pv system and solar hot water system are mounted. The tip of the pyramid is set on a patented ball-and-socket mechanism, which allows the units to follow the sun, maximizing production. The 14.9-kilowatt crystalline silicon system provides solar electricity while the water heaters provide domestic hot water and heat for in-floor radiant heating.

The Solar Decathlon highlights a range of innovative concepts that stretch the imagination regarding how solar might meet some of our energy needs. It is an exciting event for both students and those fortunate enough to see the homes on display. Congratulations to the University of Illinois team and all other participants.

All 20 homes and their descriptions can be viewed on

Drs. Robert and Sonia Vogl are founders and officers of the Illinois Renewable Energy Association (IREA) and coordinate the annual Renewable Energy and Sustainable Lifestyle Fair. The Vogls and the IREA are members of the Environmental Hall of Fame. Dr. Robert Vogl is vice president of Freedom Field, and Dr. Sonia Vogl is a member of Freedom Field’s Executive Committee. The Vogls consult on energy efficiency, renewable energy and green building. They have 3.2 kW of PV and a 1 kW wind generator at their home. Forty acres of their 180-acre home farm are in ecological restorations. They are active in preserving natural areas and are retired professors from Northern Illinois University. E-mail

From the October 28-November 3, 2009 issue

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