Power Houses: The U.S. Department of Energy Solar Decathlon
by Susan Piedmont-Palladino
Firmness, commodity, delight…and energy efficiency? Writing more than 2,000 years ago, Roman architect Vitruvius didn’t feel the need to add that last criterion to his set of requirements for good buildings. Before the Industrial Revolution there were limited options for keeping warm in the winter or cool in the summer, so every building had to respond to—and take advantage of—its own environment. A house could be neither functional nor delightful if it didn’t cooperate with the environment. The energy crises of the 1970s sparked broad interest in consciously solar-oriented design, but by the end of the 20th century many architects seemed as embarrassed by the solar houses of the ’70s as they were by the polyester suits lurking in the back of the closet. Yet solar design was hardly a new idea; in fact, designing to take advantage of the sun’s power is one of the oldest concepts in architecture. Still, more than a century of lighting, heating, and cooling our homes with fossil fuels had allowed many of us to forget about the sun as a potential friend (or even as an enemy). But, not everyone forgot…
Richard King, now director of the Solar Decathlon at the U.S. Department of Energy (DOE), had wondered why something as obviously sensible as domestic solar power had not taken hold in mainstream homebuilding circles. An engineer by training, King decided it was time to engage a new generation in this concept. And so, ten years ago this spring, the DOE issued a request for proposals to universities to compete in the inaugural Solar Decathlon, unleashing the creative power of design and engineering students to rethink the role of energy efficiency—and solar power in particular—in designing what Vitruvius might describe as firm, comfortable, and delightful houses. The Decathlon, so named for its 10 contests in categories such as energy performance, livability, and architectural achievement, was aimed directly at the integration of good architecture and good engineering in the quest for solar power. And, just to make it more challenging, teams of students would have to transport their self-sufficient solar houses to the National Mall where they would sit side by side, competing against one another in the middle of the nation’s front yard. The challenge: arrive, build, perform, and be gone in three weeks.
Expect the Unexpected
As an educator, I can attest that you never quite know what you’re going to get when you set design and engineering students free to tackle a complex problem. No matter what you ask for, you will get the unexpected; no matter how specific the rules, you will get results that challenge them. The story of the Decathlon can be told through the surprising challenges and game-changing innovations that the student teams themselves brought to the competition, stoking rivalries as fierce as any in collegiate sports. Representing a cross-section of schools from around the U.S., including one from Puerto Rico, the 2002 field proved that even working under the same tight set of rules, clever students will produce a diverse spectrum of solutions. In-state rivals Virginia Tech (VT), in the first of what would be three appearances, and the University of Virginia (UVA), in its first and only so far, faced off in 2002, each with decidedly modern entries. Virginia Tech went high-tech, exploring the qualities of translucency and extreme craftsmanship that would characterize all of their entries. But Virginia took a different path.
The UVA students nicknamed their house the “Trojan Goat” to communicate its qualities as an adaptable, resourceful, even stubborn animal sneaking into the competition disguised as a rule-abiding solar house. Fully aware that the rule structure awarded no points for green construction, the UVA team was nevertheless interested in a much larger scale of energy efficiency. As John Quale, assistant professor of architecture and faculty advisor for the team in 2002, put it, “the team became rather obsessed with the material selection process. . . reclaimed shipping palettes were taken apart and milled down for the wood rain-screen skin; copper roofing from a barn was reused for the copper skin under the rain-screen; bluestone was being replaced at the terraces of Thomas Jefferson's Rotunda at UVA and we cut it for use as the wall and floor in the sun space.” Technically, all the materials owed their existence to solar energy; some had just taken millennia to develop. The use of recycled material inside and out gave the house an instant patina, as if it had already weathered many seasons under the sun. The Trojan Goat won the architecture contest that year, living up to its name by sneaking in a belly-full of bigger sustainability issues to fuel the creative competition and one-upmanship of successive Decathlons.
After Virginia’s success in 2002, teams searched for materials with ever more interesting pedigrees. The students in Team California, the Architecture award winner in 2009, had wandered the lumberyard of one of their sponsors, listing for the owner what they wanted in exterior siding for their house. As Annessa Mattson, architecture project manager, explained, redwood fit the bill, but it was precious, legally protected, and pricey—all factors that were wrong for the message of the house. Fortunately the sponsor knew someone with a sixty-year-old stack of smoke-damaged, salvaged redwood remainders, which, when planed smooth and pieced together, gave the Refract House, as it was called, its classic California look. The team persisted in the quest for local sources for the interiors. Since California College of the Arts was the one of the schools constituting Team California, along with Santa Clara University, thinking “local” often meant looking within their own arts community for textiles, light fixtures, and even the ceramic dishes. Team California made its agenda clear: “Finally, wherever possible, we have employed technologies and design practices that we see as the future of sustainable building, regardless of their direct measure in the contest. . . Refract House does not feel like a typical ‘green’ home, or a science fair project. Solar is not an afterthought, nor is energy efficiency—they are integral parts of the house’s design.”
From Recycling to Rethinking
In 2005, teams were selecting recycled and innovative materials to try and set their houses apart from the competition. One house, however, stood out that year for different reasons. It looked at first glance as if the students had built it facing the wrong way, but the Rhode Island School of Design’s house was oriented differently to make a point. Justifiably concerned that promoting solar autonomy in single-family houses was leaving community out of the equation and avoiding the issue of energy-guzzling, low-density land-use, the RISD team oriented the long axis of its rectangular volume north/south, rather than east/west like all of the other houses. Theirs became the only house in the Village envisioned as a model for compact development. Despite its apparent inefficiency for gathering solar energy, faculty advisor Jonathan Knowles explained that too much sun can result in too much heat gain and that the north/south orientation allows greater control of illumination. Few houses have the kind of utopian solar situation the Solar Village gives Decathletes; in the real world, a good solar architect has to be able to work with whatever site is at hand. RISD took a principled risk in order to raise an issue and critique the rules; the Architecture judges felt that risk deserved some recognition and awarded the team 4th place.
As one of goals of the Decathlon is to promote the integration of solar technology with good architecture, teams wrestled with the architectural implications of the solar arrays, the actual structures of photovoltaic panels and hot water collectors. Sacrifice a desired roof pitch to an ideal solar angle? Make a statement about the solar panel array or just try to hide it? Should a solar house stand out or should it look just like its neighbors? The Technical University of Darmstadt, in Germany, one of a few international entries to compete since 2005, arrived at its first Decathlon in 2007 with an approach to the solar array that was as radical as RISD’s orientation to the site. This time, the risk really paid off. By treating the entire surface of the house as an area available to collect solar energy, and by questioning the size of the collecting elements themselves, the German team redefined the problem of architectural integration. From a distance the house looked like an elegant, shuttered box; no pitch or peak interrupted the flat profile of the roof. In addition to a semitransparent photovoltaic skylight, the house combined a familiar traditional element—shutters—but faced each one with thin photovoltaic panels. The entire faceted surface of the house collected energy, the way a tree gathers energy through its myriad leaves.
Have House, Will Travel
One of the biggest challenges for competitors, but the least visible to visitors to the Solar Village, is transporting the houses to the Mall. There are no points awarded for doing so, but getting a house from Puerto Rico or California—or even around the Beltway from College Park, Maryland—to the center of downtown Washington is really the 11th contest. Moreover, how the teams think about the problem can have a measurable effect on their houses. The University of Colorado made bio-based material the theme of its winning entry in 2005, even using bio-fuel to transport the house from Boulder.
The Virginia Tech team had decided to tackle the transportation problem as integral to the architecture, so the house was designed to travel without a trailer; its generous outside decks tilted up to protect the house and provide lateral stability on the road. Associate Professor Joe Wheeler, leader of both the 2005 and 2009 entries for VT, explained the benefits of the strategy, “We looked at a lowboy—a truck chassis that rides just six inches off the ground—because it would allow us to have a taller house. . . We had a 12-foot ceiling and didn’t have to worry about bridges and overpasses.” Thanks to the school’s industrial design program and a pedagogical tradition of working hands-on with materials, Virginia Tech’s house went on to compete against the pros in architecture, winning a 2006 Honor Award from the Virginia Society of the American Institute of Architects.
What’s Next?
The Solar Decathlon isn’t so much about producing 20 small houses each year as it is about producing a cohort of resourceful, savvy, innovative, and knowledgeable advocates for better architecture and better building. According to the Decathlon organizers, there are about 12,000 computer scientists, English majors, marketers, engineers, industrial designers, architects, and landscape architects are out in the “real world” now with an experience and expertise that will set them apart long after their Decathlon entries have been forgotten.
Even before the 2009 houses had been packed up and moved off the Mall, the 2011 hopefuls were finalizing their proposals. The Decathlon organizers had about a month to catch their breath before the review process began on the record number of hopefuls. Far from the paucity of applicants in 2002, when only eleven schools responded, the 2011 Decathlon faced a new problem: too many worthy proposals. Each Decathlon has been a giant step up from its predecessor in technology, architecture, craft, and just plain cleverness. What can we look for in future competitions? If history is a guide, look for more whole-house energy-collecting strategies using thin films, glass, and even photovoltaic paint. Look for moving screens of transparency, translucency, shading, to make the house highly responsive to changing weather conditions while balancing views and privacy. Finally, look for a team to tackle adaptive reuse. Students from Carnegie Mellon re-used parts of their 2002 house in 2005, but no team has yet returned with the same house. With Affordability now one of the ten contests, a savvy team might renovate a house from a previous decathlon, fix the bugs, refine the technology and re-enter, taking resourcefulness to the next scale. And what Decathlon fan wouldn’t want to see a favorite house back on the Mall for a re-match?
Want to learn more about the Solar Decathlon?
Find out about the evolution of the 10 contests and the final contests selected for the 2011 Solar Decathlon
Find out what happened to some of the house after the Decathlon is over
Watch video from the 2007 Solar Decathlon
Visit the U.S. Department of Energy Solar Decathlon web site
Susan Piedmont-Palladino, curator at the National Building Museum, was a consultant for the Architecture and Dwelling judging contests for the 2005 Decathlon, and is also a professor at Virginia Tech’s Washington Alexandria Architecture Center.
