In addition, conventional air conditioners use refrigerants made of chlorine compounds, suspected contributors to the depletion of the ozone layer and global warming. There are alternatives to using your air conditioning all the time. Passive cooling uses non-mechanical methods to keep a comfortable indoor temperature. The most effective method to cool your home is to keep the heat from building up in the first place. The main source of heat gain is sunlight your house absorbs through the roof, walls, and windows.
Secondary sources are heat-generating appliances in the home and air leakage.
Reflecting Heat Away Dull, dark-colored home exteriors absorb 70 percent to 90 percent of the radiant energy from the sun that strikes the home's surfaces. Some of this absorbed energy is transferred into your home by way of conduction, resulting in heat gain. In contrast, light-colored surfaces effectively reflect most of the heat away from your home. About a third of the unwanted heat that builds up in your home comes in through the roof. This is hard to control with traditional roofing materials.