"Well, there’s certainly more interest. ... But I don't think they are really coming into style yet, and the problem is cost," says Dr. Walden, a North Carolina Cooperative Extension specialist.

"To add these environmentally features -– things like solar power -- the problem is that you have a big upfront cost. For example, using wood in your home that has been harvested in an environmentally sensitive manner: One recent builder tried to do that. It adds about $3,500 up front to the cost of the house," Walden says. "For many people that's the cost of their down payment, so people pass that up.

"Or, for example, to add solar power, solar panels are going to cost you maybe upwards of $25,000. And that's the cost you have to make up front," he adds. "So I think that's really what's holding these kinds of improvements back. Now there is some optimism, I think. As more homes are built with environmentally sensitive materials and technology, there's a greater chance that these costs will come down.

"Also there are proposals for more tax subsidies, which could certainly help up front."

But right now these homes have to be marketed I think to emphasize their features rather than their cost.