Roof tiles change color based on the temperature

Roof Tiles that change color based on the temperature, Hypercolor style. In the cold they turn jet black, absorbing the sun's warmth and channeling that into the house. In heat they turn white, reflecting that same light and cutting down on cooling bills. Simple and smart. The MIT team calls the tech Thermeleon, and while early prototypes do change color as designed.
http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=2585