building envelope air tightness studies

Hi everyone,

This is a question from Australia, (I think I’m the only Australian member of BPA).

Our national building code is being updated in 2022. We currently do not address air tightness in our building code and the ‘code writers’ are reluctant to include it.

They state, "Unfortunately, air leakage testing of new dwellings in Australia has not been sufficiently extensive to develop an evidence base sufficient to allow the development of new regulation."

Does anyone know of any studies that may be available regarding air tightness of the building envelope?

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  • Hi Greg! Just seeing this interesting discussion here now. We are looking into this issue and how it relates to indoor air quality and health. I have been very impressed by the Australians pressing hard to get the nitrogen dioxide standards red... and think the same should apply indoors where we spend 90% of our time. Having unvented combustion devices - like gas stoves - can lead to many health impacts. I am attaching two recent(ish) studies as they relate to air tightness simulation but also health impacts. I think some of this modeling can be helpful in thinking through new building codes. Thanks! 

    Underhill et al. - 2020 - Simulation of indoor and outdoor air qual...

    2014. Indoor Air Quality in Green Vs Conventional Multifamily Low-I...


    RACGP - Unsafe air pollution standards up for review
  • My research team at LBNL has assembled a large database of envelope leakage measurements from homes across the US (>150,000 homes). The project website is under maintenance right now, but should be back up soon for interactive plotting. A number of papers were written describing the database and providing a regression model for predicting air leakage based on house parameters. Here's one good paper summarizing the database.  And here's a paper focusing on airtightness in retrofits. Here's a paper on estimating the population level energy impacts of airtightness retrofits. More resources can be found in our publications at


    Good luck!    

    Residential Diagnostics Database

    I think this will help.

    Building with sustainability in mind


    Building Ventilation
    Ensuring optimum ventilation performance is a vital part of building design. Prepared by recognized experts from Europe and the US, and published in…
  • The site I use is from one of our national labs.  You'll get more case studies, research papers, detailed instructions then you could ever imagine. It is sponsored by the Department of Energy.

    This will take you to Building America Solutions Center.  If you select guides A-Z then filter to topics/ thermal enclosures you'll see over 30 articles.  You can find research papers that will blow your mind!  

    Best of luck!

    Building America Solution Center | Building America Solution Center
    • Thanks Lori,

      Wow, that's a wealth of information right there! I can see myself getting lost in there for weeks.

      I greatly appreciate your assistance here. 

      • The Pacific Northwest National Lab is in my hometown.  I have some personal contacts there if you have any questions or need additional help.  Let me know and I'll send you some personal contacts.  

        They also have a cool widget that you can add to your own website. I was able to import it into my website pretty easily, and it's free!  Go to resources (at the top) then resources for energy efficient building to see how I used it.  The graphic takes you to a variety of topics, the each topic directs you to educational articles

        Lori Sanders

        Energy Incentives,INC


          Hi Lori,

          Thanks for the offer of help. We are about 20 years behind the game here.....due to going down the wrong path in a well-intended way. Very few people here know what a 'building envelope' is. It amazes, frustrates and amuses me at the same time that I am continually explaining the difference between inside and outside, conditioned and unconditioned.

          I have felt like a one-man army fighting this battle for over 10 years. My association & training with some north American building scientists, the resources of the BPA and the help offered by people such as yourself has been a great boost for me. I have actually recently been engaged by Panasonic to speak on their behalf about building science at a trade exhibition. There is a need for the discussion here and I am very fortunate to now have some good information and good people behind me.

  • In response to the chicken-and-egg conundrum, one approach that we used with success in Georgia was to request information from the manufacturers and distributors of blower doors on sales in GA. We used this as evidence that there would be enough professionals available to do the testing if the code was adopted. You might try asking and see what they come back with. It's obviously in their best interest to have these codes adopted as well.

    Good luck,


  • I'm in Hawaii and our situation is similar.  I've lobbied heavily for including airtightness in our new version of the IECC, but the arguments against it are real.  In the writeup of the bill for consideration by the Council on my island are comments I cut/pasted below  from a pdf, some formatting is lost, sorry.

    There's a chicken/egg quandary for our building departments.  They'd like to include it, but down the road when it comes time for inspections, they can't finalize a building if nobody's around to do the testing.  If there was a requirement, a market would open up for testing, but they don't want to create the market.  With no requirement, there is no big-enough market for that service.

    I am heartened that they included the SUGGESTION of a blower door test.  I'd like to believe that my island included it to prep builders for the next round of the energy code, so that if they do make airtightness mandatory they can point to the old code and say, "see? you were warned this was coming."

    I did offer them suggestions of which houses would benefit from better airtightness.  In our case, it's typically larger houses that are fully air-conditioned that are sited in hot areas.

    They did just copypaste the language on blower door testing from the IRC, as an expression that there is precedent and they're not just making something up.

    Another argument against mandating airtightness is that building depts can take a "health & safety" attitude towards codes, and if something doesn't translate immediately to a healthier, safer building like electrical codes or plumbing codes or structural codes do, it shouldn't be their responsibility so they kick the ball back to builders and architects.

    I building dept official I like and trust told me a story about a builder on this island who called someone on another island to do a blower door test.  They flew in, tested, failed the building, collected $4000, and flew away.  Now there's a sense that a BDT is an expensive thing that doesn't help because that builder got no feedback on how to actually improve the building.


    R402.4.1.2 Testing. The building or dwelling unit [shall] may be tested and verified

    as having an air leakage rate not exceeding five air changes per hour in Climate

    Zones 1 and 2, and three air changes per hour in Climate Zones 3 through 8. Testing shall be conducted in accordance with ASTM E 779 or ASTM E 1827,and reported at

    apressure of0.2inchw.g.(50Pascals).[Wherer-equifedbythe,odeffiei,T3testing

    test shall be signed by the party conducting the test and provided to the code Testing shall be performed at any time after creation of all penetrations of the building thermal envelope.

    During testing:
    1. Exterior windows and doors, fireplace and stove doors shall be closed, but not

    sealed, beyond the intended weatherstripping or other infiltration control measures.



    Dampers including exhaust, intake, makeup air, backdraft and flue dampers

    3. Interior doors, if installed at the time of the test, shall be open.

    ventilators shall be closed and sealed.

    Exterior doors for continuous ventilation systems and heat recovery

    heating and cooling systems, if installed at the time of the test, shall be turned


    Supply and return registers, if installed at the time of the test, shall be fully


    A. Hawaii County's version of this addition is consistent with the version

    adopted by Maui County.
    See: § 16.16B.R402.4.1.2, MCC.

    B. Maui Justification: Due to concerns relating to timeliness, added costs, and availability ofa certified contractor, this " blowerdoortest"isbeing

    madeoptionalinsteadofmandatory.Theregistereddesignprofessional may re q u ire this on behalfofthe o w n e r.

    • The problem of available test agencies and test equipment was addressed in the 2009 IECC (and IRC) by making BDT optional with a visual inspection. Builders could always do the visual inspection instead of BDT. Over the life of the 2009 IECC, contractors (both builders and test agencies) had time to obtain equipment and learned to identify the 'leak sites' that were important to pass the test.

      I am not personally familiar with the climate in Hawaii, but I bet it is mild enough that BDT testing is not commonly needed. If a building (residential or commercial) has no heating or cooling equipment - building leakage is far far less important that in a climate where the indoor conditions are "controlled".

      The same argument would apply for some locations in Australia. If there is no heat or A/C, then air leakage testing is a waste of time and money in terms of energy savings. But if the building is supposed to "climate control" the indoor conditions then building air leakage is important. In the case of most US residential buildings, the heating and AC cost are the biggest drivers of building energy consumption. (Of course, there are exceptions so that statement is a generalization.).

      As far as the BDT agency that flew in, tested / failed, and flew out. I bet the builder got exactly what they paid for. $4000 sounds high. But I bet most of the cost was travel. If they wanted help identifying and correcting leaks - that takes time and money. In the past, many test agencies build some time (typically an hour) into their BDT estimate for the investigation work. Many of those test agencies have removed that time because they were losing jobs to agencies that considered that an extra cost. Investigation work is usually on a dollars per hour basis. But if a plane is waiting for the investigation to be completed, the cost may be thousands of dollars per hour. If they flew commercial and shipped the equipment, they may not have been able to miss their flight.

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