What is SRI? Solar Reflective Index (SRI) measures the surface's ability to reflect solar heat and emit infra-red heat. Endura Cool Roof SRI tiles reflect solar heat and emit absorbed radiation back into the atmosphere thus help keep the interiors of the building cooler. The U. S. Green Building Council’s LEED 2.2 uses SRI as a way to evaluate the surface’s capacity to reflect solar heat. The roof of the building needs to have a minimum SRI value of 78 to qualify for LEED accreditation.