Home Energy Library
What is the best way to reduce cooling costs in the summer?
The best way to reduce the need for cooling during the hot summer months is by keeping the sun out of the home. Begin as far away from the house as possible with shade trees, trellises covered with vines, or awnings. Pay particular attention to east and west facing windows. The sun is low in the sky as it rises and sets allowing its rays to penetrate deep inside the home and making it tricky to keep out. When allowed to enter the home through windows, this solar radiation can cause the inside temperature to rise as much as 20°F on a hot day.
The most effective way to shade the home's east and west windows and walls is to plant tall trees or plant vines on horizontal trellises. Be sure to use deciduous trees and vines because their leaves provide shade in summer, but they drop them in winter when the solar gain is appreciated.
Awnings wider than the windows can provide shade, but even they are ineffective when the sun is very low in the sky and can enter the home right under the awnings. To further protect the home, whenever possible, locate porches and garages on east and west walls for additional shading. Shading large areas that can either reflect or retain and reradiate heat into the home like concrete patios and driveways is also helpful. Most homes have roof overhangs that sufficiently shade the windows.
When replacing windows, it is preferable to look for high-performance windows with low-E glazing. They look perfectly clear, yet block out a large percentage of unwanted solar radiation.
As you move closer to the home, measures tend to become less effective and more expensive to install.
Inside the home, solar gain through windows can be reduced by installing drapes with light-colored linings or blinds that can reflect sunlight. Vertical blinds are particularly effective on east- and west-facing windows. Also, choosing lighter colors for roofs and walls to reflect sunlight will reduce heat gain.