Cool Roofs Can Use a Face Lift, er, Twist?

The NYT just printed a piece on cool roofs. White reflects light. And white roofs can too—as much as 90% of the sun's heat energy, thereby significantly lowering cooling costs. Great for Florida, say detractors, but not so much for, say Michigan where a dark roof can boost warmth in winter.

Two-faced
Is it not obvious to anyone else, they should make shingles that are peaked or curved and painted two different shades. Light where it angles toward the hot summer sun, and dark where it faces the low winter sun. Case closed, next!