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Are replacement windows worth the cost? Surprisingly, if the sole reason is to reduce your energy bill, then the answer is usually no. Instead, try these methods for making your existing windows as efficient as possible.

replacement windowsQuality storm windows can double the R-factor (resistance to heat loss) of a single-pane window at far less cost than a replacement window. Photo: Gorell Windows and Doors

Replacing old windows with new energy-efficient units is a big investment. It can easily cost you $500 per window, or up to $10,000 for a typical home. But will energy-efficient windows save you money? Not right away. New windows will not save you money beyond their cost for many years. That's because even a dramatic upgrade, such as from single-pane glass to a double-pane gas-filled window, will only reduce your energy costs by $126 to $465 dollars per year according to the Department of Energy's ENERGY STAR. The actual reduction and payback period will depend upon your climate, the window selected, your fuel cost or electricity rate, how much of your home is covered by windows or glass doors, and other variables.

There are, however, several ways to improve the efficiency of your existing windows for less.

Exterior Storm Windows
Many homes that were built with single-pane windows have since been fitted with combination storm and screen windows. If this is the case with your home, be sure to push up the screens and pull down the storms as soon as the weather gets cold enough to begin running the furnace. If you do not have storm windows, or if they are in poor repair, install new quality units. Top names in storm windows include Larson and Gorell Enterprises. Storm windows improve energy efficiency by reducing air leakage and adding another layer of insulation. Don't forget to insert storm panels in your storm doors, too.

storm windowA magnetic strip around the perimeter of this interior storm windows holds it to steel channels and creates a insulating dead air space. Photo: Magnetite

Interior Storm Windows
A DIYer can install interior storm windows easily. They are available in several designs. In a magnet-sealed version from Magnetite, L-shaped metal strips are installed around the window jamb. Then an acrylic panel (purchased locally), framed with a magnetic channel, can be snapped in place from the home's interior. Other "inside" storms, such as those from Larson, mechanically attach to jamb-mounted channels. Inside storms may be used with all window types, but bear in mind that they must be removed in order to operate the primary window.

Examine your window on a cold day and feel for air infiltration. Those drafty spots are ripe for weatherstripping. Weatherstripping is available in a myriad of shapes and materials. The easiest to install (and least expensive) are V-shaped vinyl weatherstripping and foam tapes. Simply clean the surface, cut to length, peel off the adhesive's protective paper, and press into place (with your forefinger for V-shaped vinyl weatherstripping, and with your thumb for foam tape).

Apply weatherstripping around the perimeters of windows and exterior doors. Use a self-stick, V-shaped seal along edges that slide, such as at the jambs of double-hung windows. Vinyl versions of this product are easy to install and inexpensive. Metal types are more expensive but last longer. Use a foam tape along edges that press together, such as at the top and bottom of double-hung window sash, and around casement windows.

Run beads of latex caulk (or silicone caulk, but beware of the fumes and difficult cleanup, which requires solvent) at window or door joints where you can feel cold air coming through. Joints between the siding and window and door casements are prime candidates for caulk. Caulking around the perimeter of interior casings may also reduce cold air infiltration.

Plastic Film
Install plastic window insulation film across the inside of a window to create an insulating layer of air -- and protect from UV rays and glare to boot! (3M's Window Insulator Kit makes the best version of this product.) Install film with double-faced tape across the face of the window casings. When heated with a hair dryer (at low setting), the plastic sheeting becomes taut and and nearly invisible. Once installed, however, the window is no longer operable. And although it costs less than $4 per window, it's only good for one season.

insulating window treatmentsInsulated window treatments must seal to the window casing to be effective. This type runs in tracks. Photo: Window Quilt

Insulating Window Treatments
Insulating window treatments are expensive ($8 to $14 per square foot), but the results are extraordinary. With the window quilt in place, you can improve the R-value of a double-pane window from 1.86 to 6.90 for a heat loss reduction of 73 percent. A true insulating window treatment is made of specially manufactured quilting that includes several layers, including a reflective vapor barrier. The entire perimeter of such a shade is sealed to the window casing with tracks or strips of Velcro. Window Quilt, makes an excellent version. Keep in mind, however, that insulating window treatments only provide insulating value when they are is rolled down.

When Should You Replace Your Windows?
If you need replacement windows for reasons other than energy saving -- for example, wood windows that have deteriorated due to water infiltration and rot, or windows that no longer operate properly and would be too costly to repair -- it pays to go with energy-efficient windows. You may also want to upgrade your windows to make maintenance easier; it's no fun to climb on ladders to wash window exteriors. Today's new window designs eliminate all of that because you can access exterior glazing by tilting them inward. Some windows can even be ordered with a self-cleaning coating on the glazing that helps prevent dirt build up.

replacement windowsGetty Images

If you do decide on replacement windows, act quickly. The Federal tax credit of up to $1,500 for energy-efficient remodeling is scheduled to expire soon. Andersen Windows says that early November is the date you should keep in mind if you intend to taking advantage of the credit because it may take time to fill your window order and because the windows must be installed (not only purchased) by the end of 2010.


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