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The Role of Air Sealing in Determining Energy Costs and Home Comfort

Home heating and cooling accounts for 50 percent or more of the annual energy budget of the average American home. One of the more effective ways to keep your spending under control while maintaining high levels of indoor comfort is through air sealing. A well-sealed home keeps more energy inside where it belongs and prevents heated or cooled air from escaping.

Air Leaks and Insulation

The most common form of energy loss in a home is an air leak. Your furnace, heat pump or air conditioner produces heated or cooled air, but if there are leaks in your home's frame, in the ductwork or in areas such as the attic, this air can seep away before it has the chance to benefit you. Air sealing techniques are designed to find and block these leaks to prevent the expensive waste of conditioned air.

Insulation is another important element of home sealing. Insulation resists the flow of heat, which means it helps keep heat out in the summer and in during the winter. Large amounts of energy can be lost from areas where insulation levels are inadequate or nonexistent. As you proceed with home air sealing, take the time to evaluate your insulation level and add insulation where necessary.

Finding leaks

The first step in an effective home air sealing program is finding the leaks. Here are ways to do that:

  • Energy audit -- An energy audit performed by your local trusted HVAC contractor will give the best results in finding air leaks. The auditor will conduct a thorough visual inspection and numerous tests to find areas where energy is being lost. Thermographic imaging, for example, will show areas where heat loss is greatest, while surface thermometers may be used to determine where wall surfaces are warmer or cooler than expected.
  • Infiltrometer test -- An infiltrometer test, sometimes called a blower door test, is an effective way to locate even the smallest leaks. This test requires the temporary installation of a large, powerful fan in the frame of a door that leads to the outdoors. The fan pulls air out of your home and decreases the pressure inside the structure. When the pressure decreases, outside air is pulled into your home through both visible and hidden cracks, gaps and openings. The energy auditor can use measuring instruments and the infiltrometer's computer to determine the amount of air coming into your home. If there's more air coming in than would be expected, the auditor knows to look carefully for leaks. The auditor may also use such tools as a smoke pencil, which produces a thin stream of smoke that will be physically moved by air leaks and drafts.

Home Air Sealing

Some of the more common areas to focus home air sealing efforts include:

  • Doors and windows -- Use foam or rubber weather stripping to seal around the edges of doors or windows. Apply silicone caulking around the edges of window panes and latex caulking around window and door frames. Put flexible rubber gaskets or other material at the bottoms of doors to block drafts.
  • Attic -- Use latex caulking to seal holes, gaps and other leaks in the attic. Pay particular attention to the areas where the house frame attaches to the floor of the attic. Look for leaks and drafts around attic hatches, knee walls, vents, fans and light fixtures.
  • Basement -- Check the basement and foundation areas where the house frame contacts the foundation. Seal smaller holes with latex or silicone caulking and larger leaks (1/4-inch to 3 inches) with expanding spray foam.
  • Wall penetrations -- Areas in the wall where wires, pipes, utility lines or conduits enter your home should be sealed with caulking or spray foam sealant.

Duct Sealing

Since all of the conditioned air produced by your HVAC unit travels through the ductwork, any leaks in this air distribution pathway will be a significant source of loss. You or your contractor should inspect and repair the ductwork system as part of your air sealing program.

  • Check the ductwork for loose sections or broken seals at the points where sections connect. Reseat any loose segments so that they fit together tightly and firmly.
  • Immediately replace any damaged or missing sections of ductwork.
  • Seal connections between ductwork sections with mastic, a specialized sealant designed specifically for ductwork, or with metal tape. Do not use standard duct tape to seal sections because the adhesive can dry out and cause the tape to fall away.
  • Insulate the ductwork with rigid fiberboard insulation or wrap it with standard fiberglass roll insulation. This will prevent the loss of energy through the relatively thin metal of the ductwork itself.

Comfort24-7 provides high-quality heating and cooling services to customers throughout Chicago, Northwest Indiana and Southwest Michigan. Contact us today for more information on air sealing and how a tightly-sealed home can improve indoor comfort while lowering your seasonal energy bills.

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