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Profiles in home energy savings
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Published: 12/9/2007 12:19 AM

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"Rex, I am home."

As soon as Rex hears John Avenson's announcement, it quickly turns on the living room lights or raises the kitchen window shades.

If Avenson, of Westminster, Colo., asks for a DVD movie, Rex turns on the projector in his home theater.

Rex remembers to switch off the lights after Avenson leaves a room, or to pull down the shades during summer to cool the house.

No, Rex is not the butler.

Rex is a computer that recognizes Avenson's voice and helps him save energy in his house. Avenson has thermometers in rooms and instruments on the rooftop that track temperatures, solar heat and wind speed. Rex analyzes that information and makes decisions.

"When Star Trek came on the television, a computer controlled the starship Enterprise," Avenson says. "I have a computer that runs my home."

Avenson, who works for Lucent Technologies Inc., has made his 2,000-square-foot home so energy-efficient that he sent back electricity to Xcel in June, 2006, and got a $2.83 credit on his bill.

In January, he paid only $91 for his combined gas and electric bill. By comparison, an average Xcel Energy customer paid $216.

Yet, "I am embarrassed about my bill," Avenson says. "Most of it is because of (higher) natural gas use in winter."

Avenson installed hot-air panels on an outside wall. The panels take colder air from the rooms, heat it outside, and return the hot air back into the rooms _ helping cut natural gas use. He fixed solatubes to light the hallway, bathroom and his office with sunlight during day time.

More efficient than skylights, solatubes redirect sunlight into a room through highly reflective tubing that look like normal ceiling lights.

Those who know Gretchen and Ron Larson of Golden Colo., kow their passion: to experiment with ways to save energy.

Their latest experiment is annual cycle thermal energy storage.

What that means is a huge tank that holds 10,000 gallons of water. The tank gets heated by sunlight during summer, and the hot water is used in the cold winter months for various purposes. Besides the shower, laundry and other household uses, the hot water also runs through pipes under the floor and keeps the Larsons' home warm in winter.

The system needs fine-tuning, but Ron Larson is optimistic.

"We still got problems there ... but it will work," Larson says.

Larson, who has a doctorate in electrical engineering, says his stint at the National Renewable Energy Laboratory in Golden made him more energy conscientious.

The Larson home on Lookout Mountain doesn't use natural gas -- heating and cooling are done primarily by solar photovoltaic panels, although the couple has two backup wood stoves.

"The wood stoves are pretty small," says Gretchen Larson. "They really are more for aesthetics than anything else."

Their energy-efficient refrigerator runs on solar energy -- a technology Ron Larson believes could be used by rural communities in poor countries with shoddy electrical infrastructure.

Gretchen Larson says her husband's dream is to live in an energy-efficient house, and she doesn't mind when some experiments don't work.

"We just put a lot of our savings into building a house that would be efficient," Gretchen Larson says. "I'm all for it, Ron is learning and other people are learning from it."