Window Coverings

Window Coverings

While most traditional window coverings do not have insulating qualities or prevent air leakage; others, like insulated panels and window quilts, can reduce heat loss/gain and air leakage.  Not only does covering your windows improve your comfort around the home, but it is also a simple, decorative, and affordable energy-smart technique.

Preventing winter heat loss and summer heat gain.  Window coverings come in many forms, such as awnings, blinds, draperies, high-reflectivity films, mesh window screens, overhangs, shades, and shutters.  Homeowners may also want to consider planting shade trees or shrubs near windows to keep out sunlight.  This is a great way to prevent solar heat gain on hot summer days. 

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What are my Options?

Awnings.  Most modern awnings are made from synthetic fabrics that are water-repellent and resistant to mildew and fading.  Opaque, tightly woven fabrics are best, and lighter colors reflect more sunlight.

Blinds.  There are two types of blinds: interior and exterior (usually made of wood, steel, aluminum, or vinyl).  In general, exterior blinds are more effective at reducing solar heat gain than winter heat loss.

Drapes.  Draperies can be closed on summer days to prevent solar heat gain.  Medium colored draperies with white plastic backings can reduce solar heat gain through a window by up to 33%.  When drawn on cold winter days, some draperies can also reduce winter heat loss by up to 10%. It is important to note that draperies perform differently based on fabric type and color. 

High-Reflectivity Films.  Reflective films help block summer heat gain and are best used in cooling seasons on east- and west-facing windows, which have the most potential for heat gain.  In general, silver films are more effective than colored, more transparent films.

Mesh Window Screens.  Mesh screens are also effective at reducing summer heat gain. When installing, make sure that the screens are mounted in an exterior frame and that they cover the entire window.  These screens work best on east- and west-facing windows.

Overhangs.  There are many factors to consider when selecting and installing a roof overhang, such as latitude, climate, window size, and window type.  Overhangs are generally easier to incorporate into the design of a new home rather than to install in an existing home.  However, shading devices such as a “light shelf” can easily be added to the outside of a home or building.

When properly installed and oriented, overhangs can shade south-facing windows from the summer sun while still allowing sunlight in during the winter months.

Interior Shades.   Interior shades should be mounted close to the glass with sides close to the wall in order to form a sealed air space.  Dual shades can be used for greater efficiency.  They have one side that is white and highly reflective for the cooling season and one side that is dark and heat absorbing for the heating season.

Shutters.  There are two types of shutters: interior and exterior.  Both are effective at reducing winter heat loss and summer heat gain.  Exterior shutters are usually built with louvers or slats that allow air to pas through.  Interior shutters usually have insulation and are constructed to provide an air tight seal.

In general, exterior window coverings such as awnings, exterior blinds, and exterior shutters are more efficient in summer, since they stop the sun’s heat before it enters the window. In the winter, interior window coverings are better at keeping room heat from penetrating to the outside. However, even traditional interior coverings such as blinds and simple curtains can make a difference in both comfort and energy costs.

Coverings with Insulating Properties:
Window treatments such as insulated shutters and panels, and window quilts serve as both coverings and insulators.

Insulated panels.  Insulated window panels or pop-in shutters can be made of rigid foam insulation which is applied to the interior of a window.  Insulated panels are relatively inexpensive, and help prevent winter heat loss and solar heat gain like other coverings.  Usually between ½” and 1” thick, they are good insulators, with R-values between 3.8 and 7.

Window quilts. These are insulating shades made from quilt material that run on a track along your window.  Window quilts prevent winter heat loss and summer heat gain like other coverings, but they also form “dead” air space between quilt and window that allows for better insulation.

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How much can I save?

Window coverings help you to feel cooler in the summer and warmer in the winter.
Window awnings can reduce solar heat gain by up to 65% on south-facing windows and 77% on west-facing windows.
Highly reflective interior blinds can reduce solar heat gain by up to 45%.
Conventional draperies can reduce heat loss from a warm room by up to 10%.
Insulated panels have R-values between 3.8 and 7.
Window coverings allow you to save money and energy while decorating your home!

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