this old house: my life in a highly permeable membrane

by caitlin meredith

the sad little house on the day I moved in

My house breathes. That’s not the technical term for it, of course – the technical term is that it has “excessive air infiltration.” I had an energy efficiency audit last week that confirmed it. Jim from the energy utility here in Austin hooked up a blower door to my entryway and let it rip. The blower door has a red piece of canvas with a big fan in the center that covers your front doorway. It looks like it would be used to inflate a circus tent but it’s the opposite. It sucks all the air out of your house and then tests the pressure. Well, at least it tries to – my house gave it a good run for its money.

Jim told me the appropriate level of seal for an energy efficient house in this climate would have to be less than 5 air changes per hour, or ACH, for those trying to quantify energy hogs like me. (He also told me that’s measured at 50 pascals of pressure, which I’m passing on to you, dear reader, because it means nothing to me.) The little computer attached to the blower reported that my house had 35 ACH. Was this the worst he’d ever seen? No, but he did later make a casual comparison between my house and a tobacco drying barn, a structure purposely built for open ventilation. Read the rest of this entry »