Air Sealing - Why?
Photo: Our Belford project gets a stellar 0.9 ACH/50 score
A quick definition
Air Sealing - a variety of means and methods used to keep outside air from entering the home in an uncontrolled method. The key word is uncontrolled, we will get into how we bring fresh air in later in this post. Think of all the drafts an old home has around windows, doors, and utilities penetrations in the outside of the home.
Air Sealing - Why?
Again, the purpose of this blog is to attempt to bring home owners up to speed quickly, without overloading them with too much information. With that in mind lets discuss the importance of air sealing your new home by identifying what air brings with it: moisture and pollutants.
Lets start with moisture, water in liquid or vapor form is the single largest threat to your new home. Bulk air traveling through your walls brings moisture with it, soon as that hot humid Georgia heat makes to a nice cool air conditioned interior, you run the risk of condensation forms and where liquid water exists for any period of time rot and mold soon follows. Now before I scare you off your rocker lets get something straight, any decently built home to meet code will generally be just fine, but at ADG our goal isn’t “Just Fine”. Read our story if you want to know more about our mindset.
Next up is pollutants. If you suffer from allergies, or simply have an interest in reducing the amount of allergens and pollutants inside your home you main weapon is going to be keeping outside air from sneaking in (skip to the end of this post if you cant wait to see how we bring in clean air). Think of air as train car, as it passes dirt, pollen, insulation, wood fibers, and moisture it manages to carry a little bit of each with it and into your home, then ultimately into your lungs.
Energy savings is a popular topic among new home owners, and air sealing is a very cost effective way to that. Remember a couple sentences ago when I compared air to a train car, lets also connect the fact that energy rides on this car too. We all know cooling costs are brutal in the summer heat, keeping that cool air in and the hot air out is critical to keeping your energy bill down.
The extra short why: The way I see it is keeping moisture and pollutants out helps keep your house safe and you a feeling a little better. The icing on the cake is that your energy bills will be reduced too.
Standard Method of Measurement - ACH/50
The standard test method for measuring the air tightness of your home is the blower door test. A blower door test is used by installing a specialized fan in an exterior door frame to depressurize the space. As the fan operates, it measures the amount of air leaking through the building's envelope, which helps identify areas of poor insulation or air sealing.
The result: the results of a blower door test are show as a number of air changes per hour (ACH), this means how many times the entirety of the air in the home leaks out and is replaced with new air. Code currently requires a max of 5 ACH, while out homes are generally sub 2ACH and as shown above we can go below 1 ACH at times. ACH is a fanatistic and quick way to indicate air tightness, but in my mind it does shed more light on the overall quality of the home. Since ACH is a very difficult number to get down, a low number is a easy way to identify the builders that are going above and beyond to deliver you a good home and they take pride in their work.
Resource: geek out on Blower Door Testing: https://www.energy.gov/energysaver/blower-door-tests
Wondering if “houses should breath”…. read our fresh air post.