Almost all Phoenix roads are paved with asphalt, which brings on the discomforting impact of the urban heat island effect. But the progress of the city’s Cool Pavement Program holds out hope for less heat emanation from road surfaces. Phase two of the program is now underway, so more streets are being covered with a lighter hued coating that keeps temperatures above the road surfaces cooler. But Kamil Kaloush, a professor in School of Sustainable Engineering and the Built Environment, one of the Fulton Schools, says asphalt is not the only factor causing excessive heat. Whether pavements are asphalt or concrete, a key factor in mitigating heat is the overall optimization of roadway environment design elements and how that can determine how materials behave.