The Three Little Pigs probably never had an energy audit. If they did, you can bet the little porkers who built their homes with straw and wood squealed when they saw how much their brick-building buddy saved on his electric bill.
Researchers picked a size and style of house that a Tennessee family of four would like to own: two stories and about 2,500 square feet. But instead of "real" families creating data, scientists are letting 200 sensors in each house monitor exactly the same "virtual" family energy use: from cooking and laundry to teenagers opening the refrigerator door five dozen times a day.
"We configured these homes with two questions in mind," says Jeff Christian, senior researcher in the Department of Energy's Oak Ridge National Lab. "What could we do in this package of technologies that would fit into what people want, and the types of homes being built, and what package of retrofit measures could we put together to get a good chunk of savings?"
House No. 1 is a typical EnergyStar "builder house." Under the Home Energy Rating System (HERS), this house has an efficiency score of 90. In the HERS, a smaller number means a more efficient home.
House No. 2, known as the "retro" house, has some improvements to the outer structure and mechanical equipment. It earned a 64 HERS score, or about 20 percent more efficient than the standard builder house.
House No. 3 would make any treehugger proud with a score of 34 — with its solar roof panels, it provides a 55 percent energy savings over the builder house.
ORNL and TVA chose Knoxville builder John Kerr to construct the three homes. Kerr admits he was skeptical at first. After all, Christian was a government researcher; Kerr was a hands-on builder in the "real world." It didn't take long for Christian to impress him.
"I'm 50. I've been building houses for 25 years," Kerr says. "I thought I knew everything. But Jeff is like a guru. He completely understood the building techniques, the scheduling. He was a wonderful guy to work with."
Christian is a crusader for energy efficiency. And he knows he can't do his job right if he stays in his lab. So he put in plenty of time at the construction site.
"Builders have to learn to do some things differently," Christian says.
Some of the techniques are counterintuitive, such as using fewer studs, less wood and more insulation.
"Basically we used about 40 percent less wood in this house than a conventionally framed house," Kerr says. "The framing technique was completely different."
Throughout the construction, Christian also got ideas and improvements from the "real world" builders. A graywater recycling system, not in the original plans, was conceived and added after conversations with the contractor and plumber. A building inspector suggested drainage improvements.
Windows make a huge difference. The Department of Energy estimates inefficient windows cost consumers $35 billion per year in energy. The next generation of windows could reduce this by more than half.
The Knoxville test houses will be studied for seven years. During that time, the TVA will use information from them to create incentive programs for its customers, in an effort to reduce energy demand.
Ruth Hawk is community development director for the town of Farragut, Tenn., near the experimental homes.
"We feel this is kind of the wave of the future," she says. "We've been on the lookout to be educated." She and other Farragut officials toured the homes, and got detailed explanations of the energy-saving systems.
"I like the fact that they are not so complicated," she says. "The average person would not be overwhelmed to try some of these things."
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