World's 'Greenest' Home? It Depends on What You Mean by Green

Steven Glenn of Santa Monica lives in "the greenest house on the planet," BusinessWeek says. Which sounds exciting -- except Amory Lovins of the Rocky Mountain Institute also lives in "what may be the greenest house on the planet," as this video put it.

Lovins has no furnace and pays nothing to heat his home high in the mountains of Colorado, where temperatures can reach minus-40 degrees; yet super insulation and high-performance windows help make it warm enough for him to grow bananas.

So which home is greenest?