The color of the roof and walls can have an impact on the energy-use characteristics of a building. In a region with a long and demanding cooling season, it’s advantageous to have a light-colored, reflective roof that reflects solar energy before it’s absorbed into the structure and imposes a load on the air-conditioning system. The same applies to the walls, especially those facing south and west. The opposite is true of buildings in colder latitudes, which benefit from darker roofs and north- facing walls, to enhance the absorption of sunlight in the heating season.
__________
Excerpt from Energy Conservation Projects.