Energy codes have all kinds of requirements. You have to have certain R-values in walls, floors, and ceilings. Your windows have to have the right U-values and solar heat gain coefficients. The infiltration rate and duct leakage have to be…
Who among us doesn't love spending time in crawl spaces and attics? I've certainly done my time there. A lot of my friends hang out there, too. I found out in an email from the Building Performance Institute (BPI), however,…
As long as we're exploring the wonderful world of water, we ought to show some of the cool stuff it does. In my article Introduction to the Physics of Water in Porous Materials, I described hydrophilic, hydrophobic, and hygroscopic materials.…
This time of year, air conditioners are running like mad to keep people cool in their homes. Here in Atlanta, we've had a couple of weeks of hot, muggy weather, with a little break on Sunday. Now we're heading back…
Your air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you want the AC to dehumidify as little as possible because it uses extra energy and makes…
I have a confession to make: I've fallen in love with psychrometrics! After water itself, moist air has got to be the most interesting substance in building science. And the psychrometric chart, in all its many manifestations and with its…
Take a look at the photo above. See anything missing? If you don't see it yet, look at the big opening at the bottom right of the photo and you should be able to deduce what that room is. It's…
I like to tell people I'm a recovering academic. The truth is, though, that I haven't left physics behind. That would be impossible since I've been making a career in the world of building science. So, today I'm going to…
Joe Lstiburek called me last week to set the record straight. I had written an article about a study of moisture in double-stud walls in a Massachusetts home, and his company, Building Science Corporation (BSC), had done the research as…
Insulation is good. More insulation is better (although at some point, more may not be cost effective). It reduces the amount of heat a home loses in winter or gains in summer. You can get there by building thicker walls…