The housing market may have cooled off, but the interest in “green” homes is heating up.

According to the National Association of Home Builders, last year and this year were the tipping points for green homes. More than half of builders nationwide are involved in green building in some way. They estimate by 2010, 5 to 10 percent of homes will be completely green, which does not account for those homes that have some eco-friendly features.

Many local builders are also seeing the interest for homes that are efficient and environmentally friendly.

NASCAR Driver Joe Nemechek’s new 12,000 square-foot Lake Norman home is close to completion and has numerous eco-friendly features.

"The house ended up being too big, but we tried to do, just like the heating and air system, tried to be very efficient with everything we did," Nemechek said.

The home has a special geothermal heat pump which uses lake water to help heat the home. The builder, Spivey Construction, also used spray foam insulation which basically shrink-wraps the house to keep it cool in summer and warm in the winter.

“The geothermal is just that much more efficient, probably a fourth the cost of the normal heat pump for your gas,” said Willis Spivey, with Spivey Construction.

The house is filled with natural materials, from cedar ceilings to concrete floors. The cabinets are formaldehyde-free, the kitchen countertops are made of shyrestone, and a bathroom countertop is made of recycled glass. The basketball court will get a floor made of recycled rubber.

The final product is a collaboration of people devoted to the eco-friendly cause -- the builder, Spivey Construction; the interior designer, Tracie-Johnson-Sawyers; and the residential designer, Jennifer Pippin.

Pippin says the majority of her clients want green features incorporated into their home.

“I think people are more aware of what's going on in terms of the indoor air quality, trying to live healthier and help the planet.,” said Pippin, who specializes in green homes.

Spivey says the eco-friendly materials and appliances cost more upfront but will save you over time. He estimates Nemechek's monthly power bill for his 12,000 square foot home will be about $400, a third of what it would cost normally.

“A lot of them you're not going to really notice them. I'm going to notice them and my wife is going to notice them -- when you pay the bills, that's where you're going to see a lot of the efficiencies of using all your natural resources the best you can,” Nemechek said.