The American Society of Heating Refrigeration and Air Conditioning Engineers (AHSRAE) also has its Absorptivity Ratio. (For more resources click here). This ratio is based on a calculation of energy absorbed divided by energy absorbed plus energy reflected. Low absorptivity roofing materials such as new white single-ply roofs or coatings provide an absorptivity ratio of approximately 0.2, indicating that only 20% of the solar energy that reaches the surface is absorbed, and 80% is radiated or reflected into the surrounding air. High absorptivity roof materials, on the other hand-such as new asphalt or black single-ply membranes-can have a 0.9 ratio, indicating that 90% of the solar energy that reaches these surfaces is absorbed, and 10% is radiated or reflected into the surrounding air.