Construction - The Blower Door Test

To enlarge the image for better viewing, click on it.

A blower door test is the gold standard for rating the tightness of a structure or, said another way, the amount of air leaking through its envelope.  Originally, we expected the test to be done in conjunction with certification by        LEED,  Energy Star, or HERS.  However, we learned early on that our our project is too small to interest the local LEED certifiers and that it was too unique to fit the narrow Energy Star qualifications.  Our certifier remained somewhat confident, though, that our project might suit the HERS (Home Energy Rating System).  But in the final analysis, our build was even too unique for HERS -- mainly because it has no conventional HVAC system.   Moreover, none of the rating systems could account for the myriad other unique features  (summarized in outline form in a previous post) that make our build more sustainable than the rating systems are designed to handle.

Following is the slightly edited certifier's report on the blower door test summitted after our mutual decision to forgo any further effort towards HERS certification.

     "I felt compelled to write this summary of the project that I have been involved with since Jerry started almost 10 years.  He came to me wanting to certify his project so people had some idea of how energy efficient the project would be.  We started out as if we could give this project a HERS score and eventually did a blower door test on May 24, 2024.  I had already made several trips to witness the processes and insulation that were installed before drywalling so I could verify what was completed before being covered up.  

     The final (blower door) test results were 1.105 ach (air changes per hour).  Code in the state of Illinois is 3 ach.  It is quite a feat to get to 1.105.  On top of that, with the 16" of rice hull insulation and heating and cooling generated with tempered, radiant ground effect, the homes costs will be extremely minimal.

     There were other factors involved in the design of the house including built into a sloping hill, windows facing in the correct direction, natural ventilation and several other items I cannot attest to.

    It was my pleasure and a very interesting project to be involved with.  I have to say this the tightest home I have ever tested since I received my training in 1996."            (bold face and italics added).

Stan Clark

Advance Green Consulting, LLC, Maryville, IL

*          *          *          *          *          *

Over the 10 years that I have known Stan, we have bantered over the eventual blower door test.  Me:  "Stan, I hope you realize that our house will be so tight than your blower door fan will stall and burn out."  Stan:  "Ha, ha, hope you have the ego strength to handle a different outcome."  Well, the fan didn't stall but it did pull the least amount of air he had ever seen.  Both fan and ego still intact!