The City of Philadelphia has approved a new ordinance that amends their building code to require that certain buildings have cool roofs. The requirements for new construction call for all buildings with low sloped roofs to have cool roofs as defined as a product with initial solar reflectance of 0.70 and an initial thermal emittance of 0.75, as tested in accordance with the Cool Roof Rating Council’s Product Rating Program standard (CRRC-1). Exceptions include concrete and clay tile roofing whose initial solar reflectance requirement is 0.40.
The ordinance also allows for a roofing product whose thermal emittance is less than 0.75 (ex. Unpainted metal roofing) provided that its solar reflectance is equal or greater than [0.70 + 0.34* (0.75 – thermal emittance) ]. Liquid applied roof coatings that meet specific application and performance criteria are also acceptable cool roofs in this ordinance.