What is Solar Reflectivity (SR)?
Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere. The SR value is a number from 0 to 1.0. A value of 0 indicates that the material absorbs all solar energy and a value of 1.0 indicates total reflectance. Energy Star requires a SR value of 0.25 or higher for steep slope (above 2:12) roofing and a SR value of 0.65 or higher for low slope (2:12 or less) roofing. For more information, please go to www.energystar.gov.
What is Solar Reflectance Index (SRI)?
The SRI is used to determine compliance with LEED requirements and is calculated according to ASTM E 1980 using values for reflectance and emissivity. Emissivity is a material’s ability to release absorbed energy. To meet LEED requirements, a roofing material must have a SRI of 29 or higher for steep slope (above 2:12) roofing and a SRI value of 78 or higher for low slope (2:12 or less) roofing. For more information, please go to www.usgbc.org.