Air Sealing - What's the Big Deal?
On the Ballard Aperture project we have doubled our efforts to reduce unwanted air infiltration into the building. This is an issue that has flown beneath the mainstream radar for years, despite the fact that energy gurus have been talking about it for years. Now that the Washington State Energy Code requires blower door tests for every residence, envelope performance is now on the minds of more builders and is conveniently quantifiable. The results of the test produce a simple number -- how many times the volume of air inside the entire building is completely replaced within one hour at a given pressure. I could write pages about this but I don't need to -- you can read more about the test here and here and watch a video of a test here.
Simply put, buidlings breathe (even with all of the windows and doors closed) more than most people realize. There are two problems with this: Energy Loss and Lowered Indoor Air Quality
Energy Loss: Outdoor Air temperature in this area is usually cooler than what's comfortable inside, so your heating system is having to work harder to heat all of this air leaking to the inside. Blower door tests performed on a typical home in Americana tell us that if you add all of opening areas of the cracks and crevises together, it would be like leaving a window or two wide open in your home - something you would never do in January.
Indoor Air Quality: If we had a choice, we'd rather not breathe air filtered through our garage, attic, or walls every second we are inside our home. In larger buildings, severe cases of low indoor air quality are labeled Sick Building Syndrome.
How to Fix it: 1: Build a tight envelope and 2: install an HRV or ERV (a sophisticated filtration system which we have installed in this project and will blog about soon). The next post will show the measures we are taking to try and build the tightest envelope we can.