Atlanta heats up

Building Operating Management, May 2000

ATLAS also took thermal images of downtown Atlanta specifically, of Georgia State University - in 1972 and again in 1993. During that time, two distinct heat islands were formed while two existing islands grew. The four islands were approximately six to eight degrees warmer than the surrounding areas, which consisted of more trees and grass, and fewer buildings and roadways. ATLAS meaured roof temperatures at 10 GSU buildings with different types of roofs, including built-up, EPDM and modified bitumen. On-site rooftop temperatures were also taken. According to Amy Apprill at the University of San Diego, "The preliminary results determined that increased vegetation on or near rooftops, covering rooftops with lighter colored materials and maintaining the surfacing on older rooftops are ways to decrease temperature and, therefore, contribution to the urban heat island." Marty Waterfall, Patrick Downey, and the Global Hydrology and Climate Center conducted the research. The project was funded by NASA and the Universities Space Research Association.

Georgia, by amending ASHRAE 90.1, was the first state to codify the benefits of white roofs. The amendment recognizes four climate zones where insulation can be reduced when a reflective roof is used. "With the new amendment, building owners can save on insulation, while reaping the benefits of reflective roofs," says Downey.