R-Value vs Air Seal: What is More Important When Buying New Insulation?
In your insulation research you’re likely reading a lot about R-Value and how important it is, but how much are you seeing information about creating an air seal? When considering insulation for your home R-Value is important when it comes to more traditional options, but not so much when it comes to foam insulation. That’s because foam insulation achieves something that fiberglass and cellulose insulations can’t – an air seal.
R-Value measures a given insulation’s ability to stop heat transfer through conduction. Materials like fiberglass and cellulose may achieve a high R-Value but will still allow air to pass through it. This movement is actually heat transfer through convection. Basically, an insulation material can receive a higher R-Value because it limits heat transfer through physical contact. The testing for R-Value doesn't take into account air leakage and how with certain materials, like loose-fill fiberglass, hot air can actually decrease the R-Value because of air movement.
If you’re looking to buy new insulation for your home and air leakage has been a problem in the past, this is when you should look more seriously into creating an air seal with insulation.
Air Seal Insulation
An air seal is exactly what it sounds like – a seal that prevents the passage of air or vapor. If you’re experiencing air leakage in your home, you’re not alone. The U.S. Department of Energy says around 30 percent of a homes heating and cooling costs is due to air leakage. Creating an air seal with insulation can not only make your home more comfortable, but it can also make it more energy efficient.
A few reasons to air seal your home
are that it helps keep your AC unit and furnace from running constantly, it lowers those heating and cooling costs, and helps keep moisture out of your home.
Adapted from Amanda Ringler blog post.