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. |
