Weatherization projects insulate and tighten the shell of the home. Such projects include, but are not restricted to, caulking and weatherstripping, improving or replacing windows, and installing insulation.
Caulking and weatherstripping are the easiest and least expensive weatherization measures and can save more than 10% on energy bills. They are usually do-it-yourself projects. Choose your supplies carefully and follow instructions closely. High-quality materials and proper installation ensure that you receive maximum performance from your investment.
Caulking and weatherstripping are most often applied to doors and windows, which account for about 33% of a home’s total heat loss. Because windows outnumber doors, energy efficiency features of windows are particularly important to lowering energy costs.
Insulation is probably the most important consideration in improving the energy efficiency of a home. The type and amount of insulation you choose will directly affect energy costs. Factors to weigh in making a decision about insulation material include insulative value, cost, flammability, toxicity, durability, and availability. When purchasing insulation, check the product label to be sure the material meets specifications of either the federal government or the American Society for Testing and Materials. The label should indicate the insulation material, R-value, quantity, and the name and address of the manufacturer or distributor. It should also state how much area the insulation can cover, where the insulation can be installed, what the fire resistance of the material is, and what safety precautions should be taken for installation and use. For more information about insulation, see the EREC fact sheet Insulation.
If you choose to install the insulation yourself, wear proper clothing and learn how to properly install the insulation to avoid fire hazards and moisture problems. You should also determine if a vapor retarder or other moisture control measure is needed. You may also choose to hire a contractor. The Insulation Contractors of America (see the source list) can help you find a certified contractor in your area. You can also check the Yellow Pages.
Single-pane windows are the most inefficient ones, but it is possible to increase their efficiency. You can install storm windows to add insulating value and reduce air leaks. The simplest type of storm window—a plastic film taped to the inside of the window frame—is usually available in prepackaged kits. It can be in- stalled and removed easily, but it also may damage easily and reduce visibility. Another type, which uses rigid or semirigid plastic sheets (e.g., plexiglass, acrylic, polycarbonate, fiber-reinforced polyester) can be fastened directly to the frame or mounted in channels around the frame.
Storm windows made of glass can be attached to the frame with clips or screws. Storm window units should have weatherstripping at all joints, be made of strong, durable materials, and have interlocking or overlapping joints.
If your windows need to be replaced, there are many new types of energy-efficient glazing and frames on the market that suit different purposes. Glazing materials are made of glass or plastic; frames are available in aluminum, wood, vinyl, fiberglass, or combinations of these materials. Each type of glazing material and frame has advantages and disadvantages. Glass is durable and allows a high percentage of solar energy to enter buildings. Plastics can be stronger, lighter, cheaper, and easier to cut than glass, but not as durable and more susceptible to the effects of weather.
When comparing the different types of materials, note whether the glazing is most suitable for blocking or allowing solar gain. (If you live in a hot climate, you will probably want to block out solar gain). You can compare the energy efficiency of similar models by checking written information available from the retailer or manufacturer.
Manufacturers usually represent the energy efficiency of a window as the R-value, or the measure of resistance to heat flow. R-values range from about 0.9 to about 3.0. If the R-value is high, less heat will be lost. Manufacturers may also use the U-value, the measure of heat flow, to indicate a window’s energy efficiency. U-values are the reciprocal of R- values. U-values range from about 1.1 to about 0.3. If the U-value is low, less heat will be lost.
When you are comparing glazing, it may be helpful to determine if the U- or R-value is indicated for the entire window or just for the center-of-glass. window or just for the center-of-glass. A window with a high R-value based on the center-of-glass may not be as efficient as one with a lower R-value that is based on the entire window. For a more detailed discussion of windows, see the EREC fact sheet Energy Efficient Windows.