Tag: Blower Door

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Code-Blower Door Testing a Small Home

This post originally appeared on the Green Building Advisor website.

Code compliant blower door testing of a small home can be very frustrating for both the person performing the test and the homeowner or contractor who are required to have the test.  A few months ago, I tested a 952 square foot, newly constructed home with a volume of 7616 cubic feet, one of the smallest I’ve tested.  The house had a leakage rate of 416 cfm which resulted in a 3.28 ACH50 number.  A failed blower door test (my climate requires 3 ACH50 or less).  If we take that same CFM rate but increase the ceiling height to 9 feet, which changes the volume to 8568 cubic feet, 2.91 ACH50, a passing test.  Either way, 416 CFM of air moving through the blower door isn’t much, some kitchen exhaust hoods can move more air than that.  Seems unfair to punish smaller homes when blower door testing, especially when the blower door test is testing the surface of a structure, not it’s volume.

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Why You Need Blower Door Testing

This article first appeared in issue 304 of Fine Homebuilding Magazine.

I bought my first blower door in 2009, back when new construction was in a downturn and energy auditing and weatherization projects were on the rise.  I took a 40-hour energy auditing training course at a local college which included hands-on training on how to use a blower door.  It took many tests before I became comfortable in its operation and understood the information it was providing.  Though one of the more expensive tools I own, I’ve been able to keep it busy and add this specialized testing to my business’s income stream.

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Building Science-Natural Air Leakage

This blog first appeared on the Green Building Advisor website.

When conducting a blower door test, one of the ways we express the findings is with air changes per hour at 50 Pascals (ACH50).  As an example, a new home is blower door tested and found to be 2.75 ACH50, this means the entire volume of air inside the home is exchanging with the outside air 2.75 time per hour at the test pressure of 50 Pascals.  When discussing blower door testing with builders and homeowners, it can be hard for them to relate to the ACH50 number other than they know the home needs to be less than a certain level of air tightness to meet current code requirements.  Expressing the tightness as natural air leakage can sometimes be helpful.  How can we calculate the natural air change rate?  Well, there’s a formula:

ACH50/n-Factor = ACHnat Continue reading “Building Science-Natural Air Leakage”

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Building Diagnostics-Single Point vs Multi-point Blower Door Testing

This Article first appeared in the September/October issue of The Journal of Light Construction.

The main purpose of a blower door test is to confirm the integrity and continuity of the air control layer or air barrier.  I have a few different options on how to perform a test.  Which option I choose is dependent on the reason I am performing the test.

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Testing-Failed a Code Required Blower Door Test, Now What?

2012 was the first year the International Energy Conservation Code required residential construction to pass an air leakage rate test, better known as a blower door test.  My area of the country requires the test to be at or below 3 air changes per hour at the test pressure of 50 pascals (ACH50).  (Other areas, typically warmer climates require 5 ACH50.)  Most new construction in my market has no problem passing the test, but I have had a handful of houses fail, usually the failed tests are by a builder having their first blower door test or the project is a very small home.

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Testing-Setting up a Home for a Blower Door Test

This post was originally published in the April 2022 issue of the Journal of Light Construction.  www.jlconline.com

Blower door testing a home requires much more than simply setting up the equipment and running the test.

When setting up a house for a blower door test, should you seal off the bath fans? How do you address that six-inch combustion air vent in the mechanical room?  Should the overhead garage door in the attached garage be open or closed? Continue reading “Testing-Setting up a Home for a Blower Door Test”

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Shorts-Attached Structures Outside the Air Control Layer and Blower Door Testing

Whether you are performing blower door testing or hiring someone to perform the test for you, it’s a good idea to understand how a home should be setup for the test.  Should a door be open or closed?  What can be sealed off?  How to address rooms attached to the house but are outside the air control layer?  That’s today’s topic, attached garages and three season porches.  How should those spaces be setup for a blower door test?

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Energy Audit-Calculating the Cost of a Home’s Air Leaks

Air leaking into a home (infiltration) or out of a home (exfiltration) happens naturally in every home, new or old.  No matter how much air sealing is performed, we just can’t make them completely air tight.  I’ve tested some new homes that were very tight, .33 ACH50, (anything under 1 ACH50 is very good) and I’ve also tested many older ones that aren’t so tight, we can use my 1952 Cape as an example, 9.71 ACH50.  In this post, I’m going to discuss how to manually calculate the cost of the air leakage and examine what we can do with that number. Continue reading “Energy Audit-Calculating the Cost of a Home’s Air Leaks”

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Building Science-An Interview with Gary Nelson

I think most of us know of this man, one of the founders of The Energy Conservatory and designers of the Minneapolis Blower Door.  I recently had the opportunity to chat with Gary.  My intent with the interview is a little different from other interviews that have featured Mr. Nelson.   I wanted to ask questions from a practitioner working in the field point of view. Continue reading “Building Science-An Interview with Gary Nelson”