Air infiltration and air quality
From GLGI
Contents |
Why It Matters
- It is estimated that 40% of our heating expenses go to air infiltration.
- Your home's energy efficency, comfort and a healthy home environment depend on a balance of air sealing, insulation, moisture control and ventilation.
- As home owners reduce air leakage into their homes with upgraded windows, improved door seals, improved caulking, and other techniques, energy efficency improves and heating costs go down. This is often the most cost effective way to improve energy efficency and comfort. However, air tight homes may lead to poor indoor air quality. Indoor air is often more polluted than outdoor air. For a discussion of indoor air quality go to the EPA's IAQ site.
- Home owners are often concerned about over sealing their homes. The US EPA/DOE/Energy Star indicates that it is possible to over seal a house. However, it is very unlikely in older homes. There are specifications that set the minimum amount of fresh air needed for good indoor air quality. If you suspect that your house may be over sealed, hire a professional, or home energy auditor.. They have diagnostic tools, such as a leakage.Blower Door Test equipment, to measure actual air leakage.
- If your home is too tight, a heat recovery ventilator may be recommended.
What You Can Do
- Reduce infiltration of outside air into your house by first conducting a do it your self home energy audit. See the following[1] DOE/Energy Efficency and Renewable Energy site.
- Before beginning a project to reduce home air infiltration, carbon monoxide detectors should be installed near each appliance that uses gas (i.e. furnace, hot water heater, clothes dryer, cooking stove).
- After any home sealing project, have a heating and cooling technician check to make sure that your combustion appliances ( furnace, hot water heater, clothes dryer, cooking stove) are venting properly.
- Several sources of home air infiltration/loss and possible corrective actions follow.
- Fireplace. Reduce the loss of warm/conditioned air up the chimney when there is no fire burning. Fireplace dampers are generally poor metal to metal seals. In some cases they have been warped by the heat. Battic Door makes an inflatable pillow to install in the fire place damper area to reduce air leakage and backdrafts. See [2] or 604-320-9082 for details.
- Dryer Vent, Bathroom and Kitchen Vents. Have you noticed on a cold day that it is often chilly in the vicinity of these vents. These devices are connected to a 4 inch diameter duct that is open to the outdoors via an often ineffective check valve. These large infiltration paths can be more effectively closed when not in use with a dryer vent seal. Sources for this type of device include Heartland Products [3], or 888-772-2345 and Battic Door [4], 604-320-9082.
- Attic Door. The attic door can be a significant source of heated/conditioned air loss as well as moisture reaching the attic. Excessive moisture in the attic can lead to serious problems with mold and decay if the attic is not properly ventilated. Check for air leaks around the attic door with a smoldering incense stick (see the above Do It Yourself Energy Audit). Check for excessive moisture in the attic by entering the attic on a cold winter day. If there is frost in the attic there is probably excessive air leakage and/or inadequate attic ventilation. These conditions should be corrected with a more effective attic door seal. Battic Door makes available a folding attic insulator stair cover as well as a attic access hatch door. See details at [5] , or 604-320-9082. An inexpensive and effective attic hatch door seal technique is shown in the Energy Star booklet entitled "A Do- It-Yourself Guide to Sealing and Insulating With Energy Star" page 1.12. [6] Click on Home Improvement Products.
- Reduce the Chimney Effect. The chimney effect is created by air leaking into the attic (through electrical fixtures, wire oppenings, plumbing vents and the attic hatch). As the hot air generated by your furnace rises up through the house and into the attic, cold outside air gets drawn in through basement leaks to replace the displaced warm air. An excellent guide to sealing attic and basement air leaks (and reducing the chimney effect) can be found in Energy Star Publication "A Do-It-Yourself Guide to Sealing and Insulating With Energy Star". [7] Click on Home Improvement Products.
