Ten projects feature solar thermal systems.

Team New York’s Solar Roofpod has solar thermal collectors that distribute the sun’s heat through a radiant floor system. (Photo credits: Erin Holohan Haskell.)

Two years ago, the U.S. Department of Energy issued a challenge to college students across the globe: design and build a home that is comfortable, affordable, attractive and produces as much or more energy than it consumes, and bring it to Washington for a week-long competition.

The result was the 2011 Solar Decathlon, the fifth such contest  held in North America. The first European Solar Decathlon took place June 2010 in Madrid; the next contest is scheduled for 2012.

From Sept. 23 to Oct. 2, 19 student teams turned Washington’s West Potomac Park into an international solar village. The decathlon bustled with visitors of all ages, eager to learn about sustainable solutions.

The homes reflected each team’s native environment and culture, while solving local and global energy challenges. Team Canada’s TRTL home was inspired by the tipi dwelling of Treaty 7 Native Peoples in Southern Alberta. Team New York built a Solar Roofpod to sit atop mid-rise buildings in urban environments, calling it “a penthouse with a purpose.” The University of Illinois’ Re-home is a housing solution for those left homeless after a natural disaster. And Team Belgium’s E-Cube is a home-building kit that  assembles in days with a manual similar to the one that comes with IKEA furniture.

 “It’s a rare opportunity to have your vocation be your avocation - all while doing good,” student representativeElizabeth Neigertstates. “The Solar Decathlon is unique in that it offers this opportunity.”

Throughout the week, teams competed in 10 contests: architecture, market appeal, engineering, communications, affordability, comfort zone, hot water, appliances, home entertainment and energy balance. Some of the competition relied on hard data, while other areas were more unconventional. Students did laundry to test appliance efficiency and  also had neighboring teams over for dinner parties during the home entertainment portion of the competition.

University of Maryland’s Watershed house took first place overall. The team focused on solar energy with photovoltaic and solar thermal arrays, and water conservation with a green roof and surrounding wetland to recycle graywater. Second place went to Purdue’s INhome, which blended green technologies with traditional aesthetics. And New Zealand’s First Light, which featured an innovative drying cupboard that dries clothes quickly by pumping solar-heated hot water through a heat exchanger, finished third.

The University of Maryland’s WaterShed home earned first-place honors at the 2011 Solar Decathlon. The home includes an engineering system that harnesses excess energy generated by the solar thermal array.

Solar thermal solutions

Of the 19 homes in this year’s competition, 10 used solar thermal technology. The use of solar thermal technology varied among schools.

  • Event champion University of Maryland’s WaterShed includes an engineering system that harnesses excess energy generated by the solar thermal arrays.

  • Victoria University of Wellington’s First Light house, which placed third, features an innovative drying cupboard that quickly dries clothes by pumping solar-heated hot water through a heat exchanger. As an aside, the house’s name derives from New Zealand being the first place morning light shines at the start of a new day.

  • Appalachian State’s Solar Homestead includes an on-demand solar thermal domestic hot water system that uses phase-change materials to provide constant water temperature in compact storage.

  • Ohio State University’s enCORE house has a flat-plate solar thermal collector in combination with a heat pump water heater to further improve energy efficiency.

  • Team Florida, which comprises South Florida, Florida State, Central Florida and the University of Florida, has a zoned mini-split system that heats and cools in conjunction with a heat pump and solar thermal panels in its FleX House.

  • Team Massachusetts, which includes Massachussetts College of Art & Design and UMass-Lowell, has hybrid solar thermal panels in its 4D Home mounted behind photovoltaic modules for efficient heat transfer to the domestic hot water system.

  • Team New Jersey (Rutgers and NJIT) outfitted its ENJOY House with evacuated solar thermal tubes that heat domestic hot water and provide preheating for the hydronic radiant floor.

  • Team New York (City College of New York) has solar thermal collectors in its Solar Roofpod home that distribute the sun’s heat through a radiant floor system. Also, a thermal storage system uses paraffin as the phase-change material to reduce tank size by half.
  • The Tidewater, Va. (Old Dominion and Hampton) Unit 6 Unplugged house contains a hot water storage tank that replaces the auxiliary heating coil with an inline heater to minimize losses.

  • The Y container home from Team China (Tongji University) includes an integrated system using heat recovery from the solar thermal collector for the domestic hot water supply and floor heating system.

  • “One of the priorities at the Department of Energy is increasing our nation’s energy literacy,” Solar Decathlon DirectorRichard Kingnotes. “Through the Solar Decathlon, we recruited the world’s brightest, most creative minds we could find and challenged them to educate us while they educate themselves.”

    The Team Massachusetts 4D Home uses hybrid solar thermal panels mounted behind photovoltaic modules for efficient heat transfer to the domestic hot water system.

    Creative and engineering potential

    While focusing on the overall objective of the event, students also found creative uses for local materials as well as modern technology to build their homes. Team New Zealand’s First Light uses recycled sheep’s wool as insulation, whereas The Southern California Institute of Architecture and California Institute of Technology’s CHIP opted for “outsulation” with a vinyl-coated fabric mesh on the exterior of their structure.

    Appalachian State University’s Solar Homestead used 42 bifacial photovoltaic panels on its great porch and provided visitors with reflective hats to boost solar gain. Team China’s Y Container was built from prefabricated shipping containers. Several homes managed operations with iPad applications.

    Walking through the solar village, one cannot help but get excited by the possibilities and enormous potential of these young leaders. PerhapsArun Majumdar, director of the Advanced Research Projects Agency, said it best during his opening ceremony remarks: “It is critically important that this is an international event. Since you are leaders of the future, I hope you get to know each other because in the future, you leaders may be sitting across the table to figure out how to make this world a better place for your children and your grandchildren. And let the Solar Decathlon be the start of that personal friendship.”

    If this is what these students can do in two years, just imagine what they can do in a lifetime. The future looks bright, indeed.

    To learn more about the 2011 Solar Decathlon, visit www.solardecathlon.gov. The next contest is scheduled for 2013.