By Brian Limkemann
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04 Mar, 2023
If you have been around anyone discussing energy efficiency and homes, you have most likely heard them use the term "blower door testing". Amazingly, it involves a door, a blower, and, wait for it, testing. Blower door testing is a technique used to measure the airtightness of a building. It involves the use of a specialized fan, called a blower door, which is mounted in the opening of one of a building's exterior doors. The fan is used to create a pressure differential between the inside and outside of the building, which allows for the measurement of air leakage. During the test, the blower door fan is turned on to either pressurize or depressurize the building. The airflow rate and pressure difference are measured using sensors attached to the blower door. These measurements are used to calculate the air leakage rate of the building. The pressure is measured in Pascals which is 1 Newton of force applied over an area of 1 square meter. And the airflow difference noted in ACH (Air Changes per Hour). So a rating of 5 ACH 50 indicates 5 air changes per hour at a pressure of 50 Pascals. 50 Pascals is a good approximation of a 20 mile per hour wind. So if 20 MPH wind is hitting your house and you measure 5 ACH 50, then total volume of air in your house changes 5 times an hour (once every 12 minutes). What does this really mean? Think about it this way, at 5 ACH 50, your heating and air conditioning are taking outside and air conditioning enough of it to fill your entire house 5 times each hour. Sounds expensive, doesn't it? Amazingly this is a pretty good value and meets current building code. Many older homes are in the 9 ACH 50 range (yes, heating the entirety of your home every 3 minutes)! Modern homes that are build with attention given to air sealing can easily achieve less than 1 ACH 50 (I've seen results as low as .25). Sadly, most production homes are not built to this standard. But shouldn't they be? Think about how much money you'd save each year if builders paid more attention to air sealing. Sure it might cost a bit more up front and possibly take an extra day or two to build, but isn't better performance worth it? I won't even get into the environmental impact... If you're curious about how well your home performs, please contact us to schedule a consultation.