Reflective surfaces for cooler buildings and cities

Many roofs and pavements are dark coloured. In warm and sunny climates thes e surfaces become hot by absorbing sunlight. This can have the undesirable consequences of increasing the heat how into the building beneath the hot r oofs, which then increases the demand for air conditioning. The hot surface s also heat the outside air, again increasing air conditioning demand but a lso increasing the concentration of ozone (smog). We estimate the benefits of replacing (as part of routine maintenance) the present dark surfaces wit h more reflective surfaces. We conclude that it is a practical way to save energy and to reduce smog in warm climates.