Cooling your home - shading your window openings

The impact of solar radiation on buildings in hot climates could be reduced not only by orientation and effective design of the structure, but also by sufficient shading. Although it is not always convenient or economical to shade roofs, walls lend themselves to this treatment in a number of ways which can be very useful for eliminating or reducing solar radiation entering through windows. Various methods are available for screening walls and windows, and when deciding on the shading requirements each façade must be separately considered to achieve the most effective solar control.

Existing trees and shrubs provide the simplest way of protecting a low building from solar radiation. Deciduous trees are especially valuable as they do not cut out winter sunshine.

Horizontal screens are most effective against a high sun and are normally used on the north and south sides. The nearer one is to the equator, the easier it is to screen these facades with a roof overhang such as those most often used in warm-wet regions. The overhangs are generally sufficient to protect the interior of the dwelling from slanting sun and driving rain, as well as to provide shade over some portion of the surrounding area throughout the day. Balconies and cantilevering floor slabs are also used for horizontal screening.

Vertical screens in the form of closely spaced elements, vertical fins or rotating louvers are useful against the low sun on the east and west facades. Combined vertical and horizontal screening, for example, can be effective for any orientation depending on its depths and the dimensions of the opening. Whatever type of screening is used it should be placed outside the glazing, be of low thermal capacity materials to ensure quick cooling after sunset, and should be designed to prevent not only reflection on to any part of the building but also hot air becoming trapped.