The bright future of green living has been on display for the past two weeks at the National Mall in Washington, D.C., during the Department of Energy’s 2009 Solar Decathlon. The biennial contest, which wraps up this weekend, brings hundreds of university students from around the world to a temporary solar village for two weeks, where spectators can walk through student-designed houses and marvel at the latest green tech.

These solar homes have it all, including things that aren’t commercially available yet — like self-activating curled-metal shades; walls made of plants, both living and recycled; and roofs that tilt at the sun, making them efficient sun-catchers from Phoenix to Fargo. Worried about efficiency while you’re away? How about an iPhone app that controls your entire house?

Teams include engineering, architecture, graphic arts and marketing students, who typically wouldn’t work together until they reach the workforce.

Team Germany’s “surprising” design took first place overall, partly because their house performed so well in the net metering contest, which measured how much net energy the house produced and consumed throughout the competition. The house had solar panels on the walls as well as the roof, which improved its performance even with cloudy conditions. Team Germany scored 150 of 150 points in net metering, catapulting them over the University of Illinois at Urbana-Champaign to win the title.

Aside from being an unrivaled educational opportunity, the decathlon is a proving ground for a new generation of energy-efficient products and designs. Some, like floor heating tubes warmed by the sun, seem so obvious it’s a wonder every house doesn’t already have them; others are most certainly modern.

A few stand-outs:

  • Team Arizona’s hinged roof, which moves to match the angle of the sun’s rays
  • Team Missouri’s eco-roof and wall materials, harvested from crops grown in the state, including sorghum and oak
  • Team California’s instantly-hot showers, which work by circulating water through a heat pump activated by a bathroom motion detector
  • Team Boston’s micro-inverters, which power a few solar panels each and cost a fraction of the price of a regular photovoltaic electricity converter
  • Team California’s and Virginia Tech’s use of iPhone apps to control the homes’ solar-electric, entertainment, heating and lighting systems
  • Team Boston’s windows, developed with Hunter-Douglas, which combine gas, gel and air layers to form a heat-absorbing wall when the sun hangs low in the winter; heat radiates throughout the house when the sun sets.

“You learn skills like communicating, team-building, executing, all these things — we call it Startup 101,” said Preet Anand, a senior at Santa Clara University in Santa Clara, Calif., who is the lead water engineer on Team California’s Refract House. “What we have learned … you can’t compare that to any other college experience.”

Part of the decathlon’s mission is to speed up delivery of emerging technology to the marketplace. Several teams worked with companies in their home states to invent new materials or products, some of which are awaiting new patents.

Valence Energy, a company comprised of Santa Clara University alumni who participated in the 2007 contest, helped Team California design a whole-house control system that can be operated via an iPhone app, Anand said. Lighting, entertainment, heating and water systems, even the window shades all connect to a master computer users can access remotely.

“They helped make everything talk to each other. So you can be on the iPhone or the Web site, and you can change the temperature of your house from the car on the way home,” he said.

Iowa State University’s team worked with a firm called AccuTemp Energy Solutions and with Pella, the window and door manufacturer, to create a better-insulated door for its Interlock House.

Timothy Lentz, a mechanical engineering graduate student at Iowa State, said the door uses vacuum insulation panels to reach an insulation value of R40 — the level of a typical ceiling, and an unheard-of rate for a door.

“This makes it almost a wall,” Lentz said.

Incidentally, many homes are so well-sealed that special ventilation systems also had to be invented. Team Alberta, comprised of students from four post-secondary schools in the Canadian province, designed a hot and cold air exhaust system that saves as much energy as possible. An energy recovery ventilator, which is basically a box fan covered in a special material, allows heat transfer between outgoing and incoming air.

“In old homes, you don’t need to worry about mechanical ventilation because the homes were so leaky. That is not really true in newer, high-performance homes,” said Michael Gestwick, who is pursuing a master’s degree in environmental design from the University of Calgary. “Our system is highly integrated, where many other systems that you’ll see are kind of decoupled — you have one system to do the heating, and a separate one for the cooling, and a ventilating machine on top of all that. We took all these pieces and put them together and wrote control logic to make it work together.”

The teams all spent about two years designing, planning and building their homes. Each house had to be assembled at its respective university, taken apart to be trucked to Washington, and re-assembled on the Mall before the competition began. The houses all feature the latest energy-efficient appliances and home entertainment systems — teams must cook, do laundry and host movie night, among other typical household activities. The 10 categories are meant to prove that solar homes can not only be cool and efficient, but comfortable and livable.

Some teams took the latter to heart, knowing many eco-conscious consumers might not want to live in a house resembling something out of the Jetsons.

“The other houses, while they are really cool and have all the bells and whistles, they kind of look like a spaceship. They wouldn’t really fit in areas that we think of, like mid-size Iowa towns,” Lentz said.

The Iowa State house resembles a ranch-style home sliced in half, with a roof that slants toward the sun. Others took it even further — the University of Minnesota and University of Illinois Urbana-Champaign teams designed homes with traditional-looking gabled roofs, even opting to sacrifice energy-collection capacity for the purpose of aesthetics.

Form versus function is always cause for debate in architecture; Jeff Stein, dean of Boston Architectural College, part of Team Boston, said the decathlon provides a new way of thinking about both. He noted that in Western society, people spend an average of 72 minutes a day outdoors.

“Buildings are hugely important, and they are way more important than the amount of attention we’ve been giving them in the last generation. Now, here comes a different way of thinking about them, and the solar decathlon is a trigger for making that (transformation) come into play,” he said.

Plus, it will help students find jobs. Lentz, from Iowa State, said he wants to work in the realm of building and energy efficiency.

“There is a lot of room for improvement there,” he said. “I’ve met a lot of people who donated products or services who keep asking, ‘When do you graduate?'”

{!! $img_subtitle !!}

Team Germany took top honors in the 2007 decathlon, and Germany’s surPLUS home was also the winner this year, landing in the top five in nearly every category. The house is two levels, a unique design for a building that only needed to be 800 square feet. It is based on a one-room concept in which each space serves more than one function. The most bizarre may be the bedroom — when not in use, the bed is tucked away under the living room floor, which is elevated above the bedroom. At night, the homeowner can choose to pull out a single or a full-sized bed. Team members said they wanted their house to be surprising and polarizing — if for no other reason to stimulate discussion.

{!! $img_subtitle !!}

The team’s Solar Energy Efficient Dwelling, or SEED [pod], is meant to grow and adapt based on local conditions — much like a plant would. It features plenty of desert-specific innovations, including a bimetal window shade that automatically squeezes shut when desert temperatures rise (pictured). The southern wall consists of two glass windows and a cascading water wall made of recycled plastic. In the desert, outdoor temperatures drop dramatically at night; the water can transfer heat throughout the house if it gets cold, and can keep things cool during the day. “We really used the house as a research vehicle. It is a scaffolding for research, especially in the southwest’s arid climate,” said Christopher Domin, a team member. But not everywhere gets as much sun as the Arizona desert. With regionalization in mind, the team designed a hinge that can adjust their house’s southern wall and roof assembly to capture sunlight at the best angle.

{!! $img_subtitle !!}

Iowa State’s house is designed with recent retirees in mind — people who want to downsize without leaving their neighborhoods or their lifestyles. The building, called Interlock House, is meant to blend into the existing environment. “You could plunk it in somebody’s large lot and it would densify the neighborhood, and keep them around the people they are used to,” said Timothy Lentz, a mechanical engineering graduate student. Though it features plenty of inventions — like insulated doors made of evacuated tubes (pictured) — the home is designed to show that a solar home doesn’t require revolutionary technology. “With our target market of recent retirees, we didn’t want to have something that was so far in left field that they couldn’t get on board with it,” Lentz said.

{!! $img_subtitle !!}

The team’s Refract House is designed like a bent tube wrapped around a courtyard; its shape controls the entry of light. Massive windows let in the sun not just to light the home, but provide a spatial connection to the outdoors. The team, comprised of students from Santa Clara University and the California College of the Arts, took first place in the decathlon’s architectural design competition. Preet Anand, a senior at Santa Clara University, said the team’s goal was to show that solar houses don’t require compromise — neither in performance nor in aesthetics. “Most green buildings are boxes. If you have a box and I have a box and my barber has a box, then your home no longer feels like yours, it looks like your neighbor’s,” he said. “We want to show, this can go mainstream, and that starts with a home that is unique, that is yours.”

{!! $img_subtitle !!}

Missouri is one of two rural teams to use reclaimed barn wood in its design — the other, the University of Illinois at Urbana-Champaign, used parts of a barn belonging to a teammate’s relative. But the Mizzou students didn’t stop there — they used compressed sorghum to make walls, Missouri white oak for the floors, and a vegetable-oil byproduct to make chairs. “One of the prerequisites for (Leadership in Energy and Environmental Design) certification is using as many renewables as you can. I think we’ve accomplished using quite a bit,” said Sara Schafer, a senior at the Missouri University of Science and Technology. In this photo, decathlon juror Jonathan Knowles checks out the recycled sorghum interior.

{!! $img_subtitle !!}

The “ blue” house is designed with Kentucky heritage in mind. It looks like a rural Kentucky breezeway house, with a rectangular design that provides natural ventilation on sweltering summer days. It incorporates Shaker-designed furniture, a nod to a vibrant Shaker community outside Lexington. And it features images of the Kentucky country on the interior walls. But the strongest connection to home is the control station — it stays in tune with the local weather and changes the solar panels’ operation accordingly. Don Colliver, a faculty adviser to the project, said the automated weather-adaptive energy response system is the house’s most futuristic feature. “Building automation has taken a step forward with this,” he said.

{!! $img_subtitle !!}

Virginia Tech’s house is also competing in Europe’s Solar Decathlon, and the team aims to make a mark on both continents. While the house is powered by the sun, it also uses a geothermal system to heat a cement floor — a rarity in solar decathlons, where the houses must be disassembled and trucked to the competition site. The floor soaks up heat from the sun during the day, and is warmed at night by a geothermal loop system. Still, the Lumenhaus’ primary theme is light — it is made of sliding glass walls and a 9 kW photovoltaic array that generates up to 30 percent more electricity than a standard PV system.

{!! $img_subtitle !!}

While some teams used plants to help filter their water, the Penn State and Rice University teams took the term living green to a whole new level. Penn State’s kitchen features a wall of live herbs in the kitchen, convenient for cooks and for water filtration, and its roof features an array of plants among the PV panels, in an effort to keep things cool. Rice University turned that concept on its side, using a wall of greenery to cool their ZEROW house and unite it with the outdoors. In this photo, visitors check out the herb wall in Penn State’s Natural Fusion home.

{!! $img_subtitle !!}

Though the houses were designed to let in as much natural light as possible, teams had to show that artificial lights can be energy-efficient and pretty, too. The lighting design contest considers each team’s use of natural daylight and artificial light, and whether interior lighting is functional and pleasant. Some teams took it a step further — Team Germany’s house uses multi-colored LEDs that allow users to adjust the light based on their moods. Team Ontario/BC’s North House, pictured, took fifth place for lighting design.

{!! $img_subtitle !!}

Decathletes were required to “live” in their homes, a contest designed to prove each house could offer all the amenities and comforts of a modern home despite its net-zero energy use. Teams took showers, washed laundry and hosted parties where they were required to cook for other teams. In this photo, Rice University students save energy by using the sun to do more than power their washing machines — it can be an efficient dryer, too.