Can green homes really be affordable? To stand out in a still sluggish housing market, more builders are beginning to offer average-priced, ultra-efficient homes.

In Beaverton, Ore., Green One Construction Services is building a zero-net-energy development of 18 homes designed to produce at least as much power as they use.

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The three-bedroom Sage Green homes, the first five of which are complete, come with superior insulation, triple-glazed windows and solar panels. Prices start at $257,900. (You can see more pictures on Preston Koerner's Jetson Green blog.)

This month in Gilbert, Ariz., a southeast Phoenix suburb, Meritage Homes unveiled a new development -- Lyon's Gate -- that aims to be 80% more efficient than regular, code-compliant homes.

Included in the $174,900 base price are nine-inch thick exterior walls, a thermostat that can be remotely programmed using an iPhone and an ECHO solar electric/thermal system that can produce up to 10 kilowatts of power annually -- about half the amount consumed by a regular house.

"If customers respond to this, this will become the way we build houses," C.R. Herro, Meritage's vice president for environmental affairs, told the Arizona Republic. "If we built these with $50,000 worth of (green) features and charged $50,000 more, we wouldn't sell one...I'm building these for people who couldn't care less about energy efficiency."

Energy bills are estimated to run about $734 annually for the 1,640- square-foot model and $1,218 per year for the largest, 3,062-square-foot one.