I have talked many times about blower door testing, air sealing and air leaks in this blog, on the Green Building Advisor’s website, and more recently, in the pages of Fine Homebuilding Magazine. Most of what I’ve written deals with testing a home or techniques used in air sealing a home. This time I’m going to discuss the mechanisms that cause air to leak, there are only three of them, but first a little science. Continue reading “Building Science-Three Way Buildings Leak Air”
Building Science-A Benefit of Exterior Insulation
I’m a big fan of exterior insulation. It’s rarely used in my area, mostly because the State of Minnesota has eliminated that code requirement. It has to to with our wide use of polyethylene sheeting as a vapor retarder on the warm in winter side of a wall assembly and then adding a low permeance plastic insulation product as exterior insulation. These plastic foams would be the choice for most contractors, lower cost and easy to source. Very slow vapor movement in either direction when a wall assembly becomes wet. This posting isn’t going to get into the foam insulations, but more into what exterior insulation can do for a home. Continue reading “Building Science-A Benefit of Exterior Insulation”
Building Science-An Interview with Gary Nelson
I think most of us know of this man, one of the founders of The Energy Conservatory and designers of the Minneapolis Blower Door. I recently had the opportunity to chat with Gary. My intent with the interview is a little different from other interviews that have featured Mr. Nelson. I wanted to ask questions from a practitioner working in the field point of view. Continue reading “Building Science-An Interview with Gary Nelson”
Building Science-WUFI
If you’re a nerd like me, chances are you’ve heard of WUFI. WUFI is a German acronym that basically translates to heat and moisture movements through a building assembly. This is called hygrothermal analysis, it predicts wetting and drying of an assembly and lets us know if that assembly is risky. Continue reading “Building Science-WUFI”
Building Science-How to Test a Bath Fan.
Recently I was at a house conducting an energy audit when the homeowner indicated they were experiencing high humidity in the master bathroom. The windows were fogging up and they had some mold growing in one of the ceiling corners. They operate a bath fan regularly but it didn’t seem to remove any moisture. Continue reading “Building Science-How to Test a Bath Fan.”
Building Science-A Visual for Blower Door Testing
I recently tested the Code Minimum House for air tightness at the rough framing stage. We ended up where I was hoping at this first test, .55 ACH50, 140 CFM. Given the volume of the home, the leakage area is equal to approximately 15 square inches. Continue reading “Building Science-A Visual for Blower Door Testing”
Building Science-Custom Shower
Wait…What? Building science and a custom shower? Yep! As some of you may know from my Instagram feed, I can’t stay busy doing energy audit, assessments and building diagnostics or residential energy design in my area. Continue reading “Building Science-Custom Shower”
Building Science-Resources
A few months ago on Instagram, I posted my favorite resources. I spend about an hour every morning looking at several websites and Instagram feeds to see what’s new and hopefully gain knowledge. Continue reading “Building Science-Resources”
Building Science-Stack Effect
I’ve talked about the stack effect several times on this blog, but have never written a post dedicated to the subject. Stack effect is present in every home. Older, less air sealed homes (like mine) will usually have a more air exchanges due to stack effect. Continue reading “Building Science-Stack Effect”
Building Science-Ghosting
Indoor air quality can effect a lot of things, of course the biggest is people’s health. How do you know if you have poor indoor air quality? One possible indicator is a phenomenon known as ghosting. Continue reading “Building Science-Ghosting”