Shakes and shingles are generally the most popular types of roofing materials, but without the right engineering, they're also the least cool of the cool roofing options. Or, to be more precise, they're the least reflective. And you want your roof to reflect, not collect, the heat.
To improve the green qualities of these roofs, consumers can request that they be treated with reflective pigments. But even that treatment doesn't solve all the problems: A smooth roof reflects more light than a bumpy roof. A bumpy roof reflects light in many directions, and with shingles, you've got bumps all over. To help make them greener, paint them bright white.