Cool roofs use high-reflectance (light-colored or reflective) materials to reflect solar radiation and reduce building cooling loads. Reflectance of 0.65 or higher is typical for cool roofing products. Light-colored asphalt shingles, metal roofing with reflective coatings, and white or light-colored single-ply membranes are common cool roof options. The reduction in solar heat gain can reduce cooling costs 20 to 30 percent depending on building size, insulation, and climate. Cool roofs also reduce the urban heat island effect, where cities are warmer than surrounding areas due to dark roofing and pavement. Cool roofing coatings can be applied over existing roofs to improve reflectance without replacing the entire roof. Reflective coatings typically consist of elastomeric base with reflective pigments. Coating thickness and surface preparation affect durability and effectiveness. Proper surface cleaning and priming ensures good adhesion. Multiple coats may be required to achieve target reflectance. Cool roofs must still provide adequate waterproofing and durability. Regular cleaning maintains reflectance; accumulated dirt reduces the cool roof benefit. Light-colored roofs can show visible dirt, requiring periodic cleaning. Cool roof benefits are greatest in warm climates with significant cooling loads. In cold climates, the reduced solar gain during winter may increase heating costs, offsetting some cooling savings. Energy simulation should verify net energy savings in the specific climate.