Window Shading
Radiant or solar heat gain through windows can cause occupant discomfort and increased air conditioning costs. The more glass your home has, especially on east, west, and south exposures, the more important window shading is to improve comfort and reduce air conditioning bills.
Shading Options
There are many choices of shading materials and placement. Interior shading devices include venetian blinds, shades, and draperies. These devices can block up to 65% of the sun's heat that would be transferred through the window. Interior shading can improve the aesthetics of the room as well as the comfort. Insulated drapes or shades can be used to reduce heat loss in the winter and heat gain in the summer. Keep in mind that interior lighting may have been designed to take advantage of day-lighting. Reducing or eliminating day-lighting may require some additional interior lighting.
Exterior shading can block up to 95% of the sun's heat. Horizontal overhangs, awnings, tinted and reflective films,and louvres are commonly used for exterior shading. Some window films also make the glass more difficult to break, thus making them an ideal choice for security reasons as well. An awning might be preferred for reducing solar gains when building identification or aesthetic improvements are desired.
Any shading device that can be removed during non-air conditioning months is desirable over a permanent device, particularly on southern exposures. South-facing windows can be a good source of "free" heating in winter. The type of shading that will work best depends on your specific situation and needs.
