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Replacement Doors and Storm Windows

Doors and windows are necessary for ventilation, illumination, and access in every building. They are also used for framing a scenic view. As important as these features are, they also contribute to a building's air infiltration and heat loss (up to 40%). Walls have twice the R-value of an insulating door, and five times the R-value of a double glazed window. Logically, if we eliminated as many windows and doors as possible, we would have much more energy efficient houses. The building, however, could be difficult to use. The most practical solution is to make doors and windows as energy efficient as possible.

Replacing Doors

Modern doors generally have higher R-values than other building openings. The percentage of heat lost through doors, excluding sliding glass doors, is much lower than that of windows. Most heat losses or gains occur when opening and closing the door. Unless your door is damaged or difficult to seal to the door jamb, it is usually not necessary to replace it. Check the weatherstripping around your door. If your weatherstripping in poor condition, replace it. After replacing the weatherstripping, check the door seal again. If the door still does not seal all the way around the jamb, it is probably warped, or bent, and you should replace it. Adding a storm door is also a good investment.

If you decide to replace your door, modern insulated metal or fiberglass doors are a better investment than wooden doors. Even though they may cost more, they are much more durable and insulate better than wooden ones. They have the added advantage of offering more of a deterrent to possible intruders.

Most insulated door prices range from $160 to $250. One common type has a steel skin with a polyurethane foam core; usually with a magnetic strip (similar to a refrigerator door magnetic seal) for weatherstripping. This type of door needs no further weatherstripping. The R-values of most steel- and fiberglass-clad entry doors range from R-5 to R-6. A 1+ inch (3.81 cm) thick door offers better than five times the insulating value of the equivalent solid wood door.

When you buy a door, it will probably be prehung in its frame. Prehung doors usually come with wood or steel frames. In most cases, you will need to remove your existing door frame from the rough opening before installing a prehung door. The door frame must be as square as possible, so that the door seals tightly to the jamb and swings properly. It is a good idea to use expanding foam caulking to seal the new door frame to the rough opening and threshold. You should do this before adding the interior trim. This will improve the air seal and insulating quality of the door assembly.

Glass doors, especially sliding glass doors, lose heat eight times faster than other types of doors. Even if the glass doors receive plenty of sunlight during the winter, a lot of heat is lost at night. Weatherstripping the door can help reduce air infiltration. The nature of the door's design, however, makes stopping all air leaks (while still being able to use the door) impossible.

When replacing patio doors, keep in mind that French or swinging doors offer a much tighter seal, and are generally more energy efficient than sliding doors. To reduce the possibility of condensation problems, all glass doors should have a "thermal break": an insulator between the layers of glass and the inner and outer parts of the door frame. Doors manufactured with several layers of glazing, low-e coatings, and argon gas between the glass panes are a better investment than plain double glass. Over the long run, the additional cost is paid back many times over in energy savings.

Storm doors for patio doors are also available. They are hard to find, but they do exist. Insulated drapes are also a good idea.

Weatherstripping

Weatherstripping is sold in most building supply and hardware stores. You can choose from a variety of materials, including: foam rubber, EPDM rubber, felt, bent metal, and plastic.

When selecting weatherstripping, you should consider the durability and effectiveness of the material. Bent brass or aluminum are considered the most durable form of weatherstripping, but they conduct heat easily, and can be damaged by being bent the wrong way or through poor installation. Bent metal weatherstripping is also one of the most expensive weatherstripping materials. Bent plastics are similar to the bent metals, but are less expensive. They are also less durable. Most rubber and foam materials stay flexible for long periods of time, and effectively seal air leaks. You should install door sweeps and thresholds for the bottom of the doors as well.

For the best possible results from your investment, you should make certain that the weatherstripping material will stay flexible under extreme cold conditions. Also be sure to follow the manufacturer's instructions. In general, you should: 1) weatherstrip the entire circumference of the window or door jamb; 2) apply one continuous strip along each side; 3) make sure the stripping is tight at the corners; and 4) use a thickness that, when the door closes, tightly presses the weatherstripping between the door and the door jamb. This makes an air-tight seal.

Factory Storm Windows and Plastic Alternatives

In most cases, storm windows and doors are intended to be permanent additions to a home. When used with older, single- glazed primary windows, factory-built storm windows are a good investment only in milder climates. They have a high initial cost and only add R-1 or less to the window's efficiency.

If you have a window or door that is not opened for long periods of time, a less costly do-it-yourself solution is to seal it from the inside with a plastic sheet. You can make a temporary storm window or door by mounting the plastic sheet on a light-weight wooden frame with the same dimensions as the opening. Be sure to add small handles near the bottom half of the frame to easily remove it when needed. Add a strip of felt around the frame to help make it air tight. Some hardware and home improvement stores sell prepackaged kits. The plastic usually comes folded or in rolls, and is 4, 6, and 8 mils (one mil equals 1/1000 of an inch) thick. The thicker sheets are more durable. If you leave the temporary storm window up all year long, try to buy plastic that is ultraviolet (UV) resistant. It will last much longer.

High quality storm doors and windows use low-e glass. Frames are usually made of aluminum, steel, fiberglass, or wood (painted or not). Wooden storm doors require more painting and weatherstripping than the other types. Metal-framed storm doors and windows might have foam insulation in their frames.

You may choose from a large variety of storm windows and doors. Some doors have self-storing pockets for the glass in summer, and the insect screen in winter. Some storm windows have fixed, full length screens and glass panels that slide out of the way for ventilation. Others are half screen and half glass; these two components slide past each other. Some are easily removed for cleaning. All of these features add some convenience and higher costs. Keep in mind, however, that well made—and maintained—storm doors and windows increase the value of a home.

Bibliography

Articles

"A Front Door and More," M. Alvarez, Practical Homeowner, (6:4) pp. 53-77, April 1991.

"Doors for Energy Efficiency," Good Cents, (1:7) pp. 34-87, July 1991.

"Don't Throw That Window Out the Window!," Home Energy, (11:6) pp. 7-8, November/December 1994.

"'Superwindow' Retrofits Show Significant Energy Savings," M. Jackson, Home Energy, (11:5) pp. 37-40, September/October 1994.

"Replacement Windows," Consumer Reports, (58:10) pp. 664-67, October 1993.

Books

Consumer Guide to Home Energy Savings, A. Wilson and J. Morrill, American Council for an Energy-Efficient Economy (ACEEE), 1993, pp. 14-36. Available from ACEEE, 2140 Shattuck Avenue, Suite 202, Berkeley, CA 94704, (510) 549-9914. $8.00.

Certified Products Directory, National Fenestration Rating Council (NFRC), 1995. Available from NFRC, 1300 Spring Street, Suite 120, Silver Spring, MD 20910, (301) 589-NFRC. $10.00.

Sweet's General Building and Renovation Catalog (vols. 6-8), McGraw-Hill, Inc., 1995. Available from McGraw-Hill, Inc., 1221 Avenue of the Americas, New York, NY 10020, (800) 892-1165. 15 vols., $250.00 for the set. This is a very large catalog of manufacturers' products. Most public libraries have this in their reference sections.

Warm House/Cool House, (Chapter 3), M. Florman and Consumer Reports (eds.), Consumer's Union, 1991. Out of print. Check your public library or used book store for a copy.

EREC is operated by NCI Information Systems, Inc. for the National Renewable Energy Laboratory/U.S. Department of Energy. The statements contained herein are based on information known to EREC at the time of printing. No recommendations or endorsement of any product or service is implied if mentioned by EREC.

Energy Efficiency and Renewable Energy Clearinghouse (EREC)
P.O. Box 3048 Merrifield, VA 22116
Voice: 1-800-DOE-EREC
E-mail: doe.erec@nciinc.com
BBS: 1-800-273-2955

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