White roofs produce cool temperature

Previous studies have indicated that painting the roofs of buildings white could be a low tech way to reduce global worming by reflecting the sun’s rays back into space. Now the first computer modeling study to simulate the impacts of white roofs on urban areas worldwide has added more weight to such a proposal indicating that painting every roof in a city entirely white could cool the world’s cities by an average of about 0.7 degrees Fahrenheit or 0.4 degrees Celsius. Cities are particularly vulnerable to climate change because they are warmer than outlying rural areas. Asphalt roads, tar roofs and other artificial surfaces absorb heat from the sun, creating an urban “heat island effect” that can raise temperatures on average by 2-5 degrees Fahrenheit (about 1-3 degrees Celsius) or more, compared to rural areas.White roofs would reflect some of that heat back into space and cool temperatures, much as wearing a white shirt on a sunny day can be cooler than wearing a dark shirt. In addition, white roofs would have the effect of cooling temperatures within buildings. As a result, depending on the local climate, the amount of energy used for space heating and air conditioning could change, which could affect both outside air temperatures and the consumption of fossil fuels such as oil and coal that are associated with global warming.