Solar Reflective Roofing

Solar Reflective Roofing

Solar reflective roofing is an exciting new technology. Cool roof performance is a function of two radiative properties: solar reflectance and infrared emittance. These two properties define the “coolness” a roofing product contributes to green building. Solar reflectance is a decimal number less than one that represents the fraction of light reflected off the roof. A high reflectance material with a value of 0.70 (70%) has only 30% of the light from the sun retained by the roof.

Solar reflectance is the most important characteristic of a roof product in terms of yielding the highest energy savings during warmer months. The higher the solar reflective value, the more efficient the product is in reflecting sunlight and heat away from the building, resulting in lower roof temperatures.

Reflective roof coatings, also known as albedo coatings, act like mirrors, reduce solar heat by reflecting the sun’s radiant energy back into space.

Infrared emittance is a decimal number less than one that represents the fraction of heat that is re-radiated from a material to its surroundings. The emittance of a material refers to its ability to release absorbed heat. For example, a metal tool left in the sun is hot to the touch, because it has a low emissivity value. Emissivity can also contribute to a cool roof in warm, sunny climates. Roofing products with high emissivity can help reduce the cooling load on a building by releasing the remaining heat absorbed from the sun.

Contact A.D. Willis Company for more information about these products.