21st Century Barnraising

For Centuries New Englanders have gathered to help their neighbors raise barns. This past Sunday my wife, Rachel, and I joined a group of our fellow Cantabrigian's in raising the energy efficiency of a neighbor's home.

For over a year the nonprofit Home Energy Efficiency Team (HEET) has organized monthly weatherization parties for buildings here in Cambridge, MA. The hosting home provides the food, local weatherization companies donate insulation, caulk, foam, and other weatherizing essentials, and volunteers provide free labor in exchange for learning how to better insulate their own home.

Each barnraising starts and ends with a "blower door" test to determine how airtight or leaky the building is. I'd heard about blower doors before but I'd never seen one in action. It's essentially an airtight collapsible door with a large fan in the middle of it (see photo). To run a test you jam the blower door into the building's front entrance, shut all other doors and windows, and then fire up the fan which tries to pump additional air into the building. Air flow monitors connected to the fan tell you how much air is being pumped in, which in turn tells you how leaky the building is.

What I learned from the test is that even with all doors and windows closed, buildings, even well insulated buildings, still leak a massive amount of air. Based on Sunday's pre-weatherization test, all of the tiny cracks and gaps in the three story home's window frames, door frames, and various other joints throughout its walls added up to the equivalent of a gaping 40" by 10" hole.

The core HEET team, including some pro insulators, gave us our marching orders; seal up as many cracks as possible and reduce that gap!

Three hours and a half dozen boxes of pizza later, they ran a second blower test and air flow through the building had decreased by 25 percent! Not bad for an afternoon's work.

For anyone interested in joining in the fun, HEET is planning a massive weatherization blow out next month to coincide with the International Day of Climate Action on October 24.