Shades & Awnings
Anyone sitting under a tree on a hot summer afternoon knows the cooling benefits of shade, but they may not realize just how effective it can be as a low-tech, low-cost way to cut their summer cooling bills. Shading your home – with trees and other vegetation or with exterior and interior shades – can reduce the temperature indoors by as much as 20 degrees on a hot day!
About 40 percent of the unwanted heat that builds up in your house comes in through windows. Although both exterior and interior shades can control this heat gain, exterior shades – items such as awnings, louvers, shutters, rolling shutters and solar screens – are more far effective, since they block sunlight before it enters the windows.
Shade Devices outside Your Home
Awnings rate high as shading devices because they block direct sunlight. Usually made of fabric or metal, they are attached above the window and extend outward and down. A properly installed awning can reduce heat gain in your home up to 65 percent on southern windows and as much as 77 percent on eastern and western windows.
A light-colored awning does double duty by also reflecting sunlight. Maintaining a gap between the top of the awning and the side of your house helps to vent any accumulated heat from under a solid surface awning. If you live in a climate with cold winters, you will want to remove awnings for winter storage or buy retractable ones to take advantage of the desirable winter heat gain.
Aesthetically, an awning mounted at an angle of 45 degrees is pleasing to the eye. Make sure the awning does not project into the path of foot traffic unless it is at least six feet eight inches from the ground.
The amount of drop you need – how far down the window an awning should come – depends on where the window is located. On the east or west side of the house, the awning needs a drop that covers 65 percent to 75 percent of the window. Because of the higher angle of the sun, an awning on the south side needs to cover only 45 percent to 60 percent of the window to produce the same amount of shade. In either case, awnings can block much of the view from a window. Slatted awnings allow limited viewing to help overcome this disadvantage.
Louvers are an attractive option because their adjustable slats control the level of light entering a home. They operate like exterior mini-blinds and, depending on the design, can be adjusted from either inside or outside of the house. Slats can be vertical or horizontal. Non-removable, fixed louvers can also be attached to the exteriors of window frames.
Shutters are moveable wooden or metal coverings that, when closed, keep sunlight out. They can be either solid or slatted, with fixed or adjustable slats. Besides reducing heat gain, they afford privacy and security. Some shutters can help insulate windows when it is cold outside and can be opened during the day to capture the desirable winter heat gain.
Rolling shutters have a series of horizontal slats that run down along a track. Rolling shades are similar in design but use fabric. Although both options are expensive, they work well and many models can be conveniently controlled from the inside. One disadvantage is that they block all light when fully unrolled.
Solar screens resemble standard window screens, except they block light and cut glare without obstructing the view or eliminating air flow. They also provide privacy by restricting the view into your house.
Solar screens come in a variety of colors and screening materials, and some local utility companies sponsor shade screen programs. Do-it-yourself kits are available, but such screens typically do not last as long as professionally built screens.
Shade devices inside your home
To shade your home from the inside, you can use draperies and curtains made of tightly woven, light-colored, opaque fabrics that reflect much of the sun’s rays. The tighter the curtain is fitted against the wall around the window, the better it will prevent heat gain or loss. Two layers of draperies improve the effectiveness of the draperies\’ insulation when it is either hot or cold outside.
Although venetian blinds are not as effective as draperies, they can be adjusted to let in some light and air while reflecting the sun’s heat. Some newer blinds are coated with reflective finishes. To be effective, these reflective surfaces must face the outdoors. Some window manufacturers even offer “mini-blind” louvers built-in between the glass of dual-pane windows and skylights.
Some interior cellular, or honeycombed, shades also come with reflective Mylar coatings. One drawback of the design is that it blocks natural light and restricts normal air flow. Likewise, opaque roller shades can be effective when fully drawn but also cut off light and air ventilation into the room.