The Importance of Air Sealing

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“Air Infiltration can account for 30% or more of a home's heating and cooling costs and contribute to problems with moisture, noise, dust, and entry of pollutants, insects, and rodents"- NC State University, NC Solar Center

Performing Home Energy Audits throughout the years, we've found that air sealing is one of the most important ways to accomplish energy efficient homes.

Generally, the main culprit for drafty rooms, inconsistent temperatures, and high energy bills is air that has escaped unnecessarily. Through our experience with Home Energy Audits, we've found that most homes suffer from this on some level. Specifically, either conditioned air can escape your house, or unconditioned air can make its way in through unsealed ducts, or everyday cracks and holes. Thus, your home's units end working twice as hard to maintain the thermostat's setting. Outside air often gets in through crawlspaces and attics, which can flood your home with pollutants and toxins, irritating allergies and creating an unsafe living environment. The image below, published by the Department of Energy illustrates the process. Performing a home energy audit or blower door test to gauge just how much air may be escaping is a simple an effective solution to these problems.

Although some of the air leaks in your home are visible to the untrained eye — around old and untreated doors and windows, for example — much of the average home's air leakage takes place in areas you don't see. A lot of it takes place because of something called the stack effect, or chimney effect, which works like this: cold air infiltrates your cellar through leaks and cracks in the foundation and walls, and begins rising. It works its way up through the floors and/or walls, and then up into your attic through structural defects, holes in your ceiling, recessed lighting, leaky duct work, the furnace flue, the plumbing stack, or a poorly sealed attic floor. A home performance contractor doing air sealing work in your home will generally focus on the basement and the attic floor in order to minimize the stack effect, and thus minimize unwanted air movement throughout your home.

Perhaps equally important, air sealing is crucial for maximizing the performance of insulation, the other major component of your home's building envelope. The R-Value of insulation is determined under the assumption that there will be no air infiltration throughout the insulation — it assumes that there will be adequate air sealing around the insulation. Once insulation is left exposed to air movement (air moving up through your attic floor, for example), R-Value decreases.

Contact your local Elm Energy Group office to talk about the importance of air-sealing for your home or to schedule a home energy audit. It's your first and best step towards a high performance home.

Suggestions for Further Reading