SEALING AND WEATHER STRIPPING
Every building has a conditioned air "envelope." This refers to the outer edge of the areas of the building that are heated (or cooled in the summer). The envelope generally does not include attics or crawlspaces, and may or may not include basements depending upon how the building system is configured.
Gaps in the building envelope that allow air to leak in or out are a major waste of energy. These openings are usually small, but they add up fast. Some estimates say that air leaks are responsible for 25-40% of our energy costs. Some of these openings are obvious, like big gaps at doors and windows, but there are lots of other spots too: outlets in exterior walls; mail slots; rim joists and mudsills; fireplace dampers; recessed lights; and utility penetrations through the wall or ceiling like for electric, cable, phone, and hose bibs. A Classic Air Leak, Gaps around an outlet. The simple solution, foam switch & outlet gaskets
These gaps let heated air out and cold air in. In fact, as warm air moves out of higher openings it creates suction at other openings that actively pulls cold air into the home. To make matters worse, if that air is being pulled in from crawlspaces, attics, or garages it may contain contaminants such as radon, mold, auto exhaust, or other hazardous materials which reduces indoor air quality.
Sealing the building envelope is a primary contributor to energy efficiency and may reduce costs and improve comfort as much as insulation. A serious investment or even a few hours spent sealing and weatherstripping can noticeably reduce drafts and save money. Sealing improvements should always be considered before installing insulation and during any construction or remodeling. Incentives for sealing are often available from Energy Trust of Oregon.
Some sealing is more advanced and may require attic or crawlspace work and temporarily moving insulation. These measures should be discussed with a weatherization contractor.
Simple Sealing for Easy Savings
expanding foam @ hose pipe entry foam tape at leaky mailbox opening metal and rubber stripping at door frame
How to Find Leaks
The best method for assessing air infiltration is a blower door test conducted by a professional home energy auditor. This test uses a powerful fan to depressurize the home which magnifies any drafts so they are easier to locate. In addition the blower door test gives a quantifiable air exchange rate which is a helpful measure of proper ventilation to assure indoor air quality. Without a blower test the best measure is taken through visual observation of caulking and weather stripping and by feeling for drafts at openings such as doors, windows, outlets, switches, and plumbing penetrations through the floor, walls or ceilings.
THE POOR MAN'S BLOWER DOOR TEST:
There is a technique for a do-it-yourself blower door test which can help locate gaps to seal. (note: It is very important for safety to turn off any combustion device in the home before conducting this test, this includes furnaces and water heaters and their pilot lights). Click here for a link to a site that describes this method.
SAFETY NOTE:
It is critical to have adequate fresh air entering a structure. Insulation and sealing improvements can reduce the rate of air exchange within a building. When improving sealing at an existing home it would be very difficult and unlikely to create a hazardous situation, however, in some cases these measures can reduce indoor air quality and create health hazards. It is recommended to test for radon after insulation or sealing improvements and operating carbon monoxide detectors should be maintained in all homes. Monitor the home and occupants for other evidence of air quality/air exchange issues such as mildew or mold growth, excessive condensation on windows or other cold surfaces, or any change in the health of occupants such as respiratory issues. If air exchange/indoor air quality issues develop they can usually be addressed through improvements in ventilation practices or systems.
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