Darker colors absorb heat, While lighter colors don't. If a house is painted black in Arizona, The black color will absorb the heat making the temperature inside the house very hot even with the AC on. If a house in Arizona is painted White, The heat will bounce off the White color, making the temperature inside the house cooler.
Have you ever noticed people working outside in the hot sun and how you never really see them wearing black shirts or pants. This is because dark colors absorb heat, however light colors, such as white, do the exact opposite. Instead of absorbing the heat from the light, light colors reflect it. So people usually paint there houses lighter colors in hot places to keep their there houses from absorbing heat so it does not cost them so much on electricity bills for air conditioning.
