Water-cooled windows take a load off air conditioning

Glass buildings let in sunlight and heat. The problem is especially severe during Spain's hot, hot, hot summers. So aircraft engineers at the Universidad Politécnica de Madrid have found a way to use the windows themselves as cooling devices — cutting air-conditioning bills by 70%.

The method is a variation on double glazing: Two layers of glass are separated by a half-inch gap filled with circulating water that literally drains away the sun's heat. Confident that they've got a winner, the university researchers have created a spin-off company, Intelliglass, to market the technology to builders.

UPM Intelliglass (original Spanish, Google translation), via Habitat Futura and Treehugger