Here is an energy saving idea. This house uses a water tank to hold up its roof, and cool its interior. It is located in Victoria, Australia, and designed by Paul Morgan Architects. Included in the house is a rain water tank, right in the middle of the living room. The tank cools the ambient air temperature of the living room in the summer, supplies rain water for a great shower, and supports the load of the roof.

via notcot.org