Hobbit homes and "green" houses.

Hobbits do exist: http://www.simondale.net/house/index.htm

In my Energy Efficient Buildings class, we're designing a house for Portland, OR. In playing with the economics of new construction, there's a clear optimization point for energy efficiency (reducing energy costs) v. increased capital costs. My thought: is there a good way to be a sneaky environmentalist and promote the energy reductions?

It really draws attention to the complex notion of "green." Our house is less efficient than a well-designed home in Denver, but it demands less energy. Which one is "greener?"