Cool roofs are specially designed to offer increased solar reflectance and decreased thermal emittance. In other words, they reflect more of the sun's rays than your average shingle roof, and prevent the warm or cool air inside from escaping through the top of a building. Under the intense heat of the summer sun, dark shingle roofs can reach temperatures of 150 degrees Fahrenheit (65.5 degrees Celsius). The reflectance of a cool roof can cut that down by more than 50 degrees [source: EnergySavers].
Lowering the temperature of the roof itself is an advantage, of course, but the real savings are inside. A cool roof improves the interior temperature of a building, either by reflecting intense heat or trapping the air inside. That reduces the strain placed on air conditioning systems, thereby reducing the emissions that result from powering our heating and cooling. Cool roofs can be constructed with a number of materials, including special reflective paint and cool roof shingles and tiles. If you need an environmental reason to believe in the cool roof, look no further: Their reflectance can help lower the heat island effect of urban and suburban areas, which causes dramatically higher temperatures under harsh sunlight compared to surrounding rural areas [source: EPA].