Clark has been intrigued by the idea of pre-fabricated housing since 1986. The pre-fab movement has long been championed by high-end architectural publications like Dwell magazine.

Pre-fab has a couple of advantages over traditional stick-built housing that's built onsite. It allows for more architecturally rich designs and more energy-efficient building.

The now defunct Cardinal Industries tried to do a lot of pre-fab manufacturing in the eastern United States. However, their look was too "cookie cutter" and the company never took off.

Zeta Communities is one start-up in San Francisco that's now building zero-energy townhomes. These townhomes use solar energy, among other types of green energy, and also create power that can be sold down the grid. And the cost? $250,000, which is actually cheap in the San Francisco area!

Clark believes zero-energy pre-fabricated homes are very much a part of our future. It used to be that no one cared about the costs of running a home -- they just cared about what the home cost. But that was then and this is now.