Concentration of CO2 in the Atmosphere

DIY Blower Door Test

Very inexpensive fan used by author for her DIY blower door testing. It has a high cfm. Cut an oval hole in a tarp and tape the tarp to the fan. Put this in a door and let the air blow out of the house. It is magic at finding leaks! Courtesy photo.

Lori Barg

The first time I saw a blower door test I thought a freight train was running through my house from the basement and out the attic. Unfortunately, this train was running after I tried hard to insulate this 200-year-old farmhouse.

I searched online for videos of blower door tests that used theatrical smoke machines. It looks like Halloween gone crazy. The smoke doesn’t just sneak out of the house, it pours out of the house and shows you just where you need to seal.

Unfortunately, equipment for a blower door test costs around $3,500. A blower door is basically a ½ to 1 horsepower fan (it should move 300 to 5,000 cfm) placed in a tarp and sealed into a door frame.

I set out to do my own testing. I scrounged a couple adjustable poles and taped a carpet drying fan (bought for under $100, an old furnace blower works, too) into an old tarp to seal the fan in the doorway. Face the fan to blow the air out of the house. Turn off pilot lights and don’t have your woodstove burning when you do this!

If you want to do the math, then the simple, affordable way to measure your progress is with free barometric pressure phone apps. See sources below for some links on how to DIY air-seal your house.

When you are done with a DIY blower door, consider donating it to the local library and let others caulk and foam and seal the air leaks in their homes. With a bunch more air-sealing, maybe, one day, my bathroom will be warm.

Wouldn’t it be great if everyone did this? How about this? If each of the fifteen technical schools in Vermont built twelve DIY blower doors and donated them to the 180 libraries, then for only $18,000, every library in Vermont could have a blower door to lend to any resident in the state. Maybe the utilities could subsidize the cost of spray foam and caulk ($300 per house).

DIY Blower door

Free Pressure Apps

Lori Barg is a builder, geologist and hydroelectric developer. Her new patent for a modular, environmentally- friendly hydroelectric system could power some of the 80,000 existing unpowered dams in the U.S. (The U.S. has only about 2,000 hydroelectric sites, about the same as Sweden).





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