Commercial Window People. Significant air conditioning savings can be obtained by blocking solar heat before it reaches the windows, or by using special heat reflective glass coatings.
Exterior shading devices are the most effective.
Awnings, storm shutters, shade trees, porches and lanai roof overhangs are all very effective in blocking solar heat. Shades, drapes and blinds installed inside the glass intercept solar energy after it has gained entrance to the interior. The main effect of the interior shades is to trap solar heat between the drapes and the window glass. Eventually, the heat from sunlight warms the air in that space. This warm air flows up to the ceiling where it is drawn into the air conditioner through the filter.