BLOWER DOOR TEST

Michael Holigan: Most new homes these days are built with quite a bit of insulation. But even with all that insulation, there are often little cracks and crevices that haven't been sealed up properly where different building materials join. And that can mean a lot of air infiltration and losing much of the air you've paid to heat or cool. Most homes have half a mile of cracks. That's equivalent to having a window open all year round. A blower door test can measure how much air infiltration you have in your home.

Craig Smith: We come in and set up the blower door into an exterior door. It's a real tight seal canvas style door. We insert into it a fan which is capable of inserting air into the house at a fixed rate. By the R.P.M.'s of that fan we understand exactly how much pressure is coming into the house. By then shutting everything, all the exterior doors, windows and so forth, we can set that fan at a certain R.P.M. and by judging the difference between the external pressure and the interior pressure, tell you just exactly how much air is going out of that house.

M.H.: Normally you want some fresh air circulating between the outside and the inside of your home. But if too much air is coming in, your heating and cooling bills can skyrocket as you pay to heat and cool that air. How many air exchanges should someone expect on a properly sealed house?

C.S.: We normally don't try to go below .5 air exchanges per hour, because the house naturally needs some air exchange to get rid of the humidity and so forth in it. But what we don't let it do is go above a 1, 1 air exchange per hour. So somewhere in between those two is what we consider a well sealed house. The general consensus is that a house can be too tight. If you do want your house totally air tight on the outside, then you need to go to some kind of a mechanical air exchanger available on your heating and cooling system that will take and condition that air before it's brought into the house mechanically.

M.H.: The blower door test can also help you locate the areas of your worst air infiltration in your home.

C.S.: Once the house is pressured up, we take smoke sticks, go around to all the areas that we've found to be common air infiltration areas. As we'll show you, the fireplace, you'll see the air going out with the smoke stick as the door is pressured up the house.

M.H.: Besides the fireplace, you can typically expect to find air leaks around windows and doors.

C.S.: Over the tops of exterior doors, which is not normally and area that's addressed in the caulking and sealant phase of the house.

M.H.: If your house is new, the leaks may be due to places workmen forgot to caulk or not having a quality homewrap installed properly. And don't forget about gaskets on your electrical outlets.

C.S.: If your exterior sheathing is not tight, you can see the air seeping around those exterior wall plates. And that's the reason why we insert then the rubber gaskets as a final stage of the blower door.

M.H.: You can buy electrical gaskets at any hardware store or home center for just a few cents each. A blower door test should cost you somewhere around ten cents per square foot of air conditioned space in your home. It's a small expense that can save you big money on energy bills as long as you live in the home.

Episode 39 1996 - 97 Season

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