You might be familiar with cool roofs, the idea of using a bright-colored or reflective roofing material to reduce heat absorption. This has the dual effects of both cutting down on the urban heat-island effect as well as reducing a building’s solar gain and the attendant cooling load. Alas, a disadvantage of such a roof (especially in northern climes) is the loss of an extra boost from a warm dark roof in the winter. Therefore researchers have been working on a means of eating ones cake and having it too.

Last fall an MIT startup announced that they had developed a color-changing tile dubbed Thermeleon. More recently, a New York firm announced a different, simpler material that could compete with your neighbor’s biodiesel-fueled car for used fry oil.