The promise of net zero energy homes is getting more affordable thanks to the marriage of green technologies with prefab building.

A California builder named Steve Glenn who was once doing ultra-high end homes has now turned his attention to lower-priced homes that are designed on a computer and are ultra energy efficient. His company LivingHomes cranks out prefabs that are very artsy looking and can be loaded on site by a truck and put onto the foundation.

Best of all, they come with virtually no energy bills whatsoever.

I have had a bias for years that we could build homes better, cheaper, and more interesting to look at by combining factory building with computer-aided design and then creating ultra-energy efficient homes. The trifecta if you will.

This is a movement that started early last decade, but was derailed by the real estate bust. Now that housing is slowly coming back, the net zero energy home movement is gaining ground too.

Think about a house not costing you much for energy over time -- lighting, cooking, heating and cooling.

Traditional wisdom holds that building an energy-efficient home adds about 3% to 7% to the cost of home building from scratch. But Steve Glenn cracked the code, according to Fortune, and he's able to do it cheaper for the equivalent of what a traditional site-built home or a traditional energy-eating home would cost.

One of his basic models is 1,232 square feet and costs $179,000. There's so much promise out there!

At a time when there's so much debate about how we'll get the energy we need for the future, what if you never needed that energy in the first place?!