Oh, the controversies of duct design. Standard versus high-efficiency filters. Radial versus trunk and branch. Central versus dedicated return vents. Flex versus sheet metal ducts. But there's another duct debate that centers around the location of the filter. In our…
The quote below is a classic from the 1893 book, Ventilation and Heating, by John Shaw Billings. The imagery of wearing someone else's dirty underwear may shock you, but Billings makes a compelling point. We essentially do something worse whenever…
I taught Manuel about sealing the holes in air barriers, ducts, and crawl spaces. He taught me how to face my fears by sticking my arm into holes in the ground. Manuel was my best worker when I did home…
Attic access points can be a mind-blowing thermal liability. If you don't believe me, open the pulldown stairs or scuttle hole and go into an attic on a cold day. Then turn around and look down through the hole. You'll…
One of my absolute favorite conferences is coming up soon. The Building Performance Association* is holding its annual National Home Performance Conference next month in Nashville, Tennessee. When I was new in the world of building science and home performance,…
I've been known to argue for using building science terms correctly. I've written articles about how we shouldn't use the word "breathe" in relation to houses and that air doesn't have any capacity for holding water vapor. I've even written…
Are you considering replacing your current water heater with a heat pump water heater but worried that it'll freeze your basement in winter? Well, enough homes have this new technology that we now have some data on this topic. A…
If you've ever seen frost in the attic in winter, it's pretty to easy to understand why it's happening. It's the same thing that causes morning dew on the grass, frost on the exposed half of my car, or water…
The central vs dedicated return vent debate has a clear winner. But first, let me explain the terminology. A forced-air heating and cooling system has supply ducts that blow conditioned air into the rooms of your house. That's the part…
Ah, mini-splits. They’re all the rage in the world of high-performance HVAC. But what exactly is a mini-split heat pump? Unfortunately, the terminology around this technology is confusing because it’s used so inconsistently. Let’s start at the beginning. (Well, OK,…