A cool roof is a roof that reflects more sunlight and emits more heat than a conventional roof, lowering the temperature of the building and the surrounding air. A cool roof can have high solar reflectance (the ability to reflect sunlight) and high thermal emittance (the ability to release heat). A cool roof can benefit a building and its occupants by:
- Reducing energy bills by decreasing air conditioning needs
- Improving indoor comfort and safety for spaces that are not air conditioned
- Decreasing roof temperature, which may extend roof service life
- Lowering local outside air temperatures, thereby lessening the urban heat island effect
- Reducing peak electricity demand, which can help prevent power outages
- Decreasing power plant emissions by reducing the demand for energy to cool buildings
There are many types of cool roof materials and products available, such as membranes, shingles, coatings, stone/rock, metal, and tile with high solar reflectance. The choice of a cool roof depends on the type of roof (sloped or low-sloped), the climate, the budget, and the preferences of the building owner.