Shades Save Home Energy 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 20o Fahrenheit 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.
Awnings
Awnings rate high 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
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
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.
Screens
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.
Inside your home, draperies and curtains made of tightly woven,
light-colored, opaque fabrics 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.
As you can see, the shading options are many. When deciding which to use,
consider whether you need to open and close them daily or just put them up for
the season. Also think about how they will affect natural ventilation through
your windows.
For more information on shading your home, contact the Energy Commission's
hotline (toll free in California) at 800-772-3300.
Article Sources:
Cooling Your Home Naturally
The Energy Efficiency and
Renewable
Energy Clearinghouse (EREC)
P.O. Box 3048
Merrifield, VA
22116
800-363-3732
Home
Energy Guide
California Energy Commission
1516 Ninth
Street
Sacramento, CA 95814
800-772-3300 (toll free in
California)
916-654-5106
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