Recent MIT graduates have devised an ingeniously simple way to save money on energy: Thermeleon color-changing roof tiles.

When it’s cool, the tiles turn black, absorbing more of the sun’s warmth. When it’s hot, the tiles turn white, reflecting the extra heat away. With that simple transition, Thermeleon color-changing roof tiles could be a natural addition to green homes.

The white tiles could save 20 percent of cooling costs. That’s a significant energy savings, and all from a simple idea. And we have to give props to the MIT übernerds who came up with “Thermeleon” color-changing roof tiles.