Does a White Roof Reflect Heat?

Energy Savings

• By reflecting rather than absorbing the solar energy of sunlight, a white roof keeps the building cooler. This reduces the overall cooling costs for the building. Tests conducted by the National Nuclear Security Administration on its own buildings resulted in an average energy savings of $500,000 annually per 2 million square feet of white roofing. Smaller projects could see proportional savings. U.S. Energy Secretary Steven Chu was quoted as saying that energy savings of 10 to 20 percent could be realized in most buildings in a 2009 CNN report.

Urban Settings

• Urban settings have a higher concentration of roofs than rural or suburban areas. Compounding the heat accumulation of dark roofs is the heat absorbed by dark roadways, which are also more prevalent in urban areas. The effect of both of these factors can result in summer temperatures up to 5 degrees higher in urban areas than in similar rural areas, according to the NCAR.

Climate Differences

• The benefits of white roofs increase with the amount of sunshine the building receives. Greatest benefits occur in warm climates with consistent year-round sunshine. Trees or buildings that shade the roof also can impact the amount of benefit gained by installing a white roof.

Other Colors

• Architects are choosing tan or light brown shingles in some projects rather than white roofs. While the light-colored shingles have a smaller heat reflecting rating than white, they still offer an energy savings over darker shingles. This is a trade-off between energy efficiency and a pleasing building appearance.