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Climate and Context Define 2013 Solar Decathlon

It’s not enough to design a house specifically for the desert; you’ve got to ask, “Which desert?”

By Leigh Franke

In this year’s Solar Decathlon, it’s going to take a lot more than energy efficiency to win. The U.S. Department of Energy’s biennial competition among college students to design solar-powered houses has become the Olympics of architectural sustainability in all its forms. Though houses have always been judged on many objective sustainable building criteria, including energy and water usage, the competition continues to gain prestige and attract interest as design expectations get higher, more nuanced, and more climatologically attuned.

Though the houses will be judged in Irvine, Calif., after the October competition, a majority will return to their location of origin, covering climates from Arizona to Calgary, Alberta, in arid deserts to dense urban settings. While the houses in the 2002 inaugural competition exhibited designs that closely resembled uniform temporary housing associated with modular construction, today’s students know that for a design to be truly sustainable, it must be as distinct as the cities and towns from which they came.

The Mojave is not the Sonoran

While a significant number of teams are based in areas seemingly similar to hot, sunny Irvine, the University of Nevada, Las Vegas team would be quick to tell you otherwise. Assistant Professor of Architecture Eric Weber explains how deserts are quite different from one to the next. “The Mojave gets about half the rain of the Sonoran in Arizona, and while going from 12 inches to 6 inches doesn’t sound like a big difference, it has a profound impact on the way the plants grow and the environment,” he says. “I had to ask the students what it means to make a house in the Mojave Desert as opposed to somewhere else.”

One feature, a perforated screen assembly that protects the DesertSol house from the sun, finds a subtle way to reference its city of origin’s relationship to its natural environment. “Las Vegas has a very different character during the day than at night, as does the desert as a whole,” says Weber. “The idea came from the mesquite trees that dot the desert, one of the few that can survive this climate. They have very small leaves, so the light that comes through is very distinctive. We thought, ‘Wouldn’t it be great if we could protect the house with these mesquite trees?’ But you can’t bring a mesquite tree to the competition, so we used digital fabrication technology to create the shade pattern on the screen. During the day you see the shade pattern of the mesquite tree, but from the outside you can’t. At night, when you light it from the inside, you see this imagery projecting across the screen assembly like a big billboard. Changing from day to night is sort of what defines this place.”

On the solar path

In a far different climate and culture, Middlebury College in rural Vermont has designed the InSite house to embody holistic sustainability. Based on five core concepts of “InSiteful” design, the house seeks not only to be self-sustaining, but to cultivate relationships and community involvement at large to ensure an ongoing commitment to green design. The design uses maple harvested from the college’s forest, reclaimed barn wood siding, cabinets made by local craftspeople, and dishware made by students.

Before designing the house, the team sought a location that would most benefit Middlebury’s downtown and found a vacant lot close to the campus on underutilized Shannon Street. Recent graduate and team manager Cordelia Newbury explained how the house’s signature formal and sustainability feature came about only when the team realized that the chosen location did not face solar south. To compensate, they designed the “solar path,” a portico-like structure topped with solar panels that meets the energy efficiency needs of the house, but also defines a community space for kids and neighbors. “It’s really our most marketable aspect of the design. We could see it on city sidewalks or parks,” says Newbury. “Our home is really about supporting a community, so we wanted it to extend from the interior into the exterior.”

‘Let’s be outside more’

Farther south, in a much larger community, the University of North Carolina, Charlotte’s UrbanEden house seeks to create the ideal urban infill home. Project manager and graduate student Clarke Snell says the team started with the question, “What would make our lives better?” With such a large team, it was difficult to find common ground on some issues, says Snell, “but when we talked about what we’d like to experience more [of] in Charlotte, everyone said, ‘Let’s be outside more.’ It sounds simple, but it’s pretty radical.” The house’s exterior space is ultimately larger than the indoor space, an attribute that can’t be said of many urban houses.

Because of Charlotte’s naturally temperate weather, the ability to spend more time outdoors could significantly lower power use. “If you create a situation in the city where you’ve got an inviting, comfortable, private outdoor space, then you’re not burning fossil fuels by heating or cooling your space,” Snell says.

But for the days when you can’t sit outside, UrbanEden incorporates a geopolymer cement concrete (GCC) envelope developed on campus to protect the house from the elements and act as a sound barrier from the bustling city life. Though it is as sturdy as traditional Portland cement concrete, GCC is produced with significantly less energy, emits no carbon dioxide during curing, and can be made from a variety of local materials. It also lends the house the feel of a sleek, urban loft. Following the competition, the house will be used to further research the efficiency of the GCC for use in other high-performance buildings, which is “really what the Solar Decathlon should be about,” says Snell.

Building back better

How do you design a home in a region and climate that are often destructive? Team Kentuckiana, a collaborative formed by Ball State University, the University of Louisville, and the University of Kentucky, knew that for their house to be sustainable it would have to be indestructible—at least in terms of tornadoes. The students became interested in disaster relief housing following a deadly tornado that struck Henryville, Ind., in March 2012, and from researching post-Katrina housing in New Orleans. They approached Mark McGinley, a professor of civil and environmental engineering at the University of Louisville, with their idea. “They had been reading about how, after a few years, many of the victims of Katrina were still living in temporary substandard living environments, and we thought, ‘We’ve got to do better—build back better.’”

Team Kentuckiana’s Phoenix House uses durable materials such as metal roofing, rather than shingles, cement fiberboard systems, and structural insulated panels for exterior walls. A safe room in the bathroom is resistant to flying debris. The house can be built on a variety of foundations, but the students used one designed to minimize deformation during transport, a concept that also makes it resistant to overturning and settlement flooding, according to McGinley. The house can also temporarily sleep up to eight people, making it easier to get people “back into the community, build it back, and back into stores to recover the economy,” he says. The house also uses reclaimed wood, which could be incorporated from fallen houses as a symbol of continuity.

Just the existence of such a wide, rich range of climatically and environmentally attuned houses provides hope for young designers that “sustainable” can become synonymous with design, rather than its descriptor. And while picking the winners from the 20 teams competing might be the pinnacle of the competition for the 300,000-plus people expected to visit, the enduring measure of the teams’ designs will occur after the houses return to the places that inspired them.


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The University of Nevada, Las Vegas’ DesertSol. Image courtesy of Team University of Nevada, Las Vegas.

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Middlebury College’s InSite. Image courtesy of Team Middlebury College.

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The University of North Carolina at Charlotte’s UrbanEden. Image courtesy of Team University of North Carolina, Charlotte.

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Team Kentuckiana’s Phoenix House. Image courtesy of Team Kentuckiana.


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