The primary purpose of a sunshade is to control the amount of direct
sunlight through your building's windows.
Southern, Eastern, and Western exposures of your building will derive benefits from solar shading. Southern exposure is the easiest to shade and provides the greatest energy savings. Occupants, however, will appreciate any reduction in morning sun glare (Eastern exposure) and afternoon sun glare (Western exposure). In some climates, these exposures can generate large energy savings as well. Northern exposures do not require solar shading. The only reason to shade a Northern exposure is to create uniformity in the building appearance. Otherwise, virtually no energy benefit can be gained from shading the North side of a building (again, we are referring to a location in the Northern Hemisphere).
Based on the solar altitude and azimuth and orientation of your building, shading methods will vary. A shelf system is best utilized on Southern exposures and will allow the best configuration for energy savings. Variations in the shelf location, projection, and blade spacings will optimize the energy benefits. The objective is to maximize shading during peak cooling season while allowing direct sunlight and heat gain during the heating season. In most of the southern climates, the need for shading throughout the cooling season generates the greatest energy savings, so we will optimize the shading for this period (April 15 through September 1). This altitude is 60° in our example.