TOPICS > Science

Competition Puts Energy-Efficient, Solar-Powered Homes on Display

October 23, 2007 at 6:40 PM EST


MARGARET WARNER: A striking new Main Street went up on the National Mall in Washington last week: an avenue of 20 solar-powered homes. The pre-constructed houses were reassembled virtually overnight by teams from 20 universities in the U.S. and around the world, all finalists in the third Solar Decathlon, a contest sponsored by the U.S. Department of Energy.

All these 600- to 800-square-foot structures had one thing in common: They were powered exclusively by the sun. The decathlon is the brain child of Department of Energy physicist Richard King. His aim was to kick start creative thinking about how to design and build solar homes from the ground up, and not just from the architecture and engineering students on the teams.

RICHARD KING, Director, Solar Decathlon: We’re also trying to teach the professionals, you know, come learn from these universities, who are our best and brightest and our storehouse of new ideas, to come and look and see what these new-generation technologies have. And we’re also trying — you know, if the builders want to start doing this, they need a market, so we’re also trying to educate the consumer, the public to say, “Wow, these houses are really awesome. We want to have one; I want to live in one. Where do I get one?”

MARGARET WARNER: To make it to the finals, all these houses had to meet exacting standards of efficiency and livability, while relying on their own entirely self-contained solar energy systems.

RICHARD KING: We make them wash dishes, wash clothes, light their space, do heating and cooling. They must maintain their house between 72 and 76 degrees Fahrenheit, 40 percent and 60 percent humidity, and they also have to charge an electric vehicle. And the team that gets the most miles charging their electric vehicle wins Contest 10, which is getting around.

MARGARET WARNER: Spurred by rising energy costs and concern over climate change, some 200,000 people came to see these decathlon homes, double the crowd of the 2005 contest and quadruple the number in 2002. Jackie Knightshade works near the Mall.

JACKIE KNIGHTSHADE, Washington, D.C., Resident: I’m concerned about the greenhouse effect and what’s happening with the Earth. And I just wanted to come out and see what I can do, what I can incorporate from here into my everyday living. And I do want to put panels on my home, the home that I’m living in now.

MARGARET WARNER: Gunner Holmquist, who brought his son from Spokane, Washington, for the event was looking for another quality, as well.

GUNNER HOLMQUIST, Event Attendee: Whether this is livable, if it’s a people-friendly kind of space. You know, can people live in these buildings? Not just the ideas and the theories, but the German building is absolutely livable. You just want to walk in there. And other buildings look like a spaceship, which is too much. It’s too much metal.

Solar Decathlon criteria

MARGARET WARNER: The houses were judged and points awarded over the course of the week in 10 different categories, for energy efficiency, marketability and aesthetics, among others. The architecture prize went to the team of students from Darmstadt Technical University in Germany.

Their home dazzled onlookers and judges alike, with its soon-to-be-patented use of photovoltaic cells embedded in louver doors on a glassed-in porch. A computer-driven mechanism constantly adjusts the louvers to take best advantage of the sun's angle.

Architecture graduate student Joerg Thoene is a member of the design team that worked for 16 months on this house.

JOERG THOENE, Technische Universitat Darmstadt: On this side right here, you can see the windows and the cells. It's three-pane windows. It's very well and highly insulating, the materials. And this allowed us in the winter to open the louvers and actually have the inside space be heated up through the sun, so we do not need much leftover energy to really acclimatize the inside.

MARGARET WARNER: In Germany, you sometimes go for a couple of weeks without seeing any sun. How does a house like this work in that kind of climate?

JOERG THOENE: We have used some solar panels that are actually working very well with not really direct sunlight, but also when it's kind of cloudy. You can still generate enough power to run the house.

MARGARET WARNER: With its innovative electronics and materials, this house came at a hefty price: at least $600,000 in construction costs alone. But in Germany, Thoene said, the house will generate an immediate payback.

JOERG THOENE: We are planning on hooking up the house to the grid, to electrical grid. So whenever we have power, you can just feed it into grid. And actually, in Germany, we get paid good money for feeding in.

Bringing solar energy to U.S. homes

MARGARET WARNER: In the U.S., such programs are only offered only on a state-by-state or county-by-county basis. That's one reason why fewer than a quarter of a million homes in the United States are believed to be using some form of active solar energy.

Several contestants tried to address the cost factor, including this house that won the market viability prize. A simple cedar-clad structure designed by students at the University of Illinois at Urbana-Champaign, it costs just $160,000 to build. It's most innovative technology was the use of heating and cooling panels that looked like the back of a refrigerator and, in fact, use ordinary refrigerant.

Jason Wheeler, a 27-year-old architecture graduate student, explained.

JASON WHEELER, University of Illinois, Urbana-Champaign: If you open a fridge and put your hand inside, it should be cold theoretically. If you touch the back of the fridge or the sides of a fridge, lots of times you'll feel a lot of heat. We're using that same kind of system to heat and cool our home. And, basically, it's reversible, so that during the wintertime we can heat inside and during the summer we can cool the inside.

MARGARET WARNER: Bottom line is, every single thing in this house, including the washer and drier, it's all from the sun. The basic energy is all from the sun.

JASON WHEELER: That's true. When we turned this house on for the first time, and we were doing our finishing touches on construction and using solar-powered circular saws to finish the house, it was really, really neat to know that our house wasn't hooked up to anything but free energy that's coming from the sun.

Simple but innovative design

MARGARET WARNER: Doug Lowe, whose Charlottesville, Virginia, firm builds green houses was one of the professional builders on the jury. He said this house had great appeal to contractors because it used off-the-shelf materials and was simply, though ingeniously, designed.

When you look at this house, how easy is this to build? How economical is it to build?

DOUG LOWE, Green Builder: It appears in this case, they've tried to use materials that are readily available in the marketplace. That always helps the situation. And I would advocate that any kind of green building or environmentally sensitive building project can be built for at or near -- just, you know, not very much more above regular building costs.

In the building industry, many technologies already exist that just need to be implemented that are not rocket science, not hard to do, it's just a matter of implementation and getting our head out of the sand.

MARGARET WARNER: For most of the week, competition for the grand prize see-sawed between the German house and the so-called LEAF House, designed by students from the University of Maryland. Amy Gardner was their faculty adviser. Their house was totally solar-powered, but had another interesting feature, as well.

AMY GARDNER, University of Maryland: Our house has several innovative water features that handle water. One of them that you can see right behind me is the green wall, what we call our green wall. Runoff from the roof comes into our gutter and then down into a kind of custom-designed irrigation system and then eventually into the green wall. And the water trickles from module to module and probably never actually reaches the ground. So runoff from the roof is delayed or detained from actually reaching the ground, and therefore it doesn't contribute to erosion.

MARGARET WARNER: And, meanwhile, you don't have to water your plants?

AMY GARDNER: And, meanwhile, you don't have to water your plants.

MARGARET WARNER: But in the end, Darmstadt and its louvers edged out Maryland and its green wall. Energy Secretary Samuel Bodman awarded the grand prize Friday.

SAMUEL BODMAN, U.S. Energy Secretary: Ladies and gentlemen, it's my great personal honor to present your 2007 Solar Decathlon champions, the Technical University of Darmstadt.

MARGARET WARNER: The fourth Solar Decathlon will be held in the fall of 2009.

JIM LEHRER: To see a slideshow of all the homes in the Solar Decathlon competition, visit our Web site at