You may already know where some air leakage occurs in your home, such as an under-the-door draft, but you'll need to find the less obvious gaps to properly air seal your home.
For a thorough and accurate measurement of air leakage in your home, hire a qualified technician to conduct an energy audit, particularly a blower door test. A blower door test, which depressurizes a home, can reveal the location of many leaks. A complete energy audit will also help determine areas in your home that need more insulation.
Without a blower door test, there are ways to find some air leaks yourself. First, look at areas where different materials meet, such as between brick and wood siding, between foundation and walls, and between the chimney and siding. Also inspect around the following areas for any cracks and gaps that could cause air leaks:
You can also try these steps to depressurize your home to help detect leaks:
If you don't want to turn off your furnace, you can just turn on all your exhaust fans to depressurize your home.
Other air-leak detection methods include the following:
Shining flashlight at night over all potential gaps while a partner observes the house from outside. Large cracks will show up as rays of light. Not a good way to detect small cracks.
Shutting a door or window on a piece of paper. If you can pull the paper out without tearing it, you're losing energy.