Air Sealing

The Department of Energy defines air leakage (also known as air infiltration) as outside air that enters a house uncontrollably through cracks and openings.

Although some owners think a leaky house results in necessary ventilation for a home, it is unwise to rely on air leakage for ventilation. During cold or windy weather, too much air may enter the house, and during warm or calm weather, too little. The result? Uneven temperatures and higher enerby bills.

Insulation does not prevent air leakage

• The most common insulation (fiberglass) does not stop air leakage. In older homes, dirty fiberglass is a telltale sign of air movement. It simply collects dirt like a filter.
• Certain types of insulation, such as dense-packed cellulose and certain foams, can be effective at reducing airflow as well as heat flow, although may not have been installed with air sealing in mind. There are likely still air leaks in the home from which conditioned air (either heated or cooled) can escape.
• During winter months every cubic foot of warm, conditioned air that leaks from the living space due to either the stack effect (warm air rising) or via exhaust fans is replaced by cold, unfiltered, raw air entering the home at the lower levels.

What are the benefits of air sealing?

The Department of Energy states that air infiltration can account for 30 percent or more of a home’s heating and cooling costs. It can contribute to problems with moisture, noise, dust as well as the entry of pollutants, insects and even rodents.

Reducing air infiltration can significantly cut annual heating and cooling costs, improved building durability and create a healthier indoor environment.