The name of the game is the sun. The house had a lot of windows to let sunlight in. He built solar collectors, which were basically tanks of water. As the heat dissipated from the water, it would heat the house. You could let more water out of the collectors if it got too hot (ie: summer).<br><br>He took insulation very seriously, as well as the position of the windows. More windows towards the side of the house that faces the morning/afternoon sun. I believe the whole house was built into the side of a small mountain. I wish I could remember the exact reason for the mountian; I'm sure it had something to do with heat radiating from it.<br><br>The big thing that struck me was the number of windows; lots of skylights.<br>