Cooling your home - shading your
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.