Multi Family Auditing

I'm curious to hear from anyone with experience in Multi Family Auditing what your thoughts on the muti-point blower door test are, and if there are ideas for performing a valid audit without the need of 5+ blower doors/auditors.



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  • Training on MF Blower Door Testing

    I am doing a hands-on three day training, April 12 - 14, 2012 in Aurora, Illinois. It is intended to teach protocols for testing multifamily buildings, how to assess a building, to plan efficient testing, the mechanics of using all major available testing systems, and acquiring & analyzing data. While the focus will be on residential buildings, the techniques and analysis methods involved are directly applicable to all types of conditioned buildings of less than 2 million cubic feet in volume. Participants will attend two days of classroom training and one day of field work performing multiple tests in an apartment building. As a result of this training you will be able to identify the appropriate test protocols for building configurations, determine appropriate test mechanics based on building systems, analyze blower door data from test procedures, identify problems, understand infiltration theory and calculate energy loss.


    Wabonsee Community College in Aurora is offering the course. Insight Property Services is doing all the legwork (Thanks, Joe!!) For more info, see Or, e-mail me...

  • So what happened here?? Did "phil" get banned??

    I quit trying to accomplish anything in this discussion because some juvenile kept spouting off with a bunch of stuff clearly motivated solely by his desire to be a wisea _ _.

    Now I see that everything he dumped in this discussion has been stripped out.

  • I am a little confused of the controversy here about testing.

    The health care analogy without testing we are simply phoning in a diagnosis

    The cost of a blower door test?  You buy one blower door and can perform thousands of tests. If you are in this industry and do not own one buy one now. They are a valuable tool.

    30 thousand homes have been built the same so no need to test? I have been in and out of spaces more as a contractor than an auditor or assessor. I can tell that off the same plan and same crew you will get a difference from house to house. Move occupants in for ten plus years and they will interact and make changes. I contend that they might look the same but will not test the same.

     Before I start a performance based job I will test and not make assumptions. I will guarantee improvements by performing a test in and test out with results that can be verified by other professionals. I must admit that sometimes it seems redundant as I can visibly see problems but I am often surprised by what I did not expect to see.

    I do not see the blower door being an added cost but part of the service. 

    As far as the multi family testing procedures I have no experience whatsoever. There were some excellent answers by industry professionals that was interesting and informative. This is why I come to this site, to learn and interact with professionals. It would seem this test is more complicated and would add costs however what are the options. Shoot in the dark and hope for results?  How do you know what you have performed is safe to the occupants?

    • My limited experience is in KY and VA.  I haven't yet encountered a house that is below the BAS.  I work on a team that audits multifamily buildings, including multi-point blower door testing.  My job is to take the data collected and figure out what makes sense from an economical point of view to do in order to save energy.  I see a lot of funds going toward doing multi-point blower door tests, and I struggle to get funds for things like duct sealing.  This is frustrating for me.  We are required to put in continuously running fans due to ASHRAE standards.  The risk of buttoning things up too tight is zero.

      When this job is over, I will concentrate on my own business as a home energy auditor.  I want to continue to work with multifamily buildings, on a private level, because I see a huge opportunity to save energy.  I question the efficacy of multi-point blower door tests.  I would rather use utility bills to individualize units that are consuming a lot of energy, and a thorough IR imaging of the building to help pinpoint where the weaknesses in the envelope are.  Neither of those two tools are being used in the program I am working in.

      My interest in this thread is to find out what others think, and I'm fairly pleased so far, but I'm still not convinced one way or another.

      • Good discussion going here....great forum for this type of more "global" chatter.

        Jon, to your website idea.  My trepidation here is that a little bit of knowledge can be a dangerous thing.  The tightening-up of a building envelope is virtually incompatible in the presence of atmospherically vented combustion appliances (thinking small homes here...).  I have seen some *scary* situations with CO concentrations in the products of combustion.  Then you have Mr. DIY spend a weekend air sealing every possible envelope penetration because he just read about it on the 'Net, and a bunch of people get CO poisoning and die.  Not that there isn't a way to best educate people to this issue, but it really takes a trained professional to properly assure the safety of a combustion appliance after the building envelope has been altered.

        A few other thoughts:

        1. Duct sealing is significantly lagging envelope improvements in terms of auditor/industry awareness.  And my experience w/incentive programs is that they can make duct sealing cost-prohibitive based on stringent testing requirements.  Duct testing can take a long time, and to test-in and test-out as BPI, etc requires drives the cost of the retrofit measure to unacceptably high levels.  Its a tricky situation, but duct sealing in both single and multifamily homes is a huge deal.  We are doing a disservice if ducted distribution systems do not get enough attention.

        2.  I think our idea of a multifamily home is largely a walk-up with a dozen or so units in it.  My work is mostly in NYC.  How about a 300,000 sq ft 25 story building w/300 units, 6 elevators, amenity spaces, multiple air handlers, and stack effect craziness that drives infiltration and air quality concerns?  Lots of these buildings in big cities, especially on the east coast. Huge energy savings opportunity, but the complexity of building interactions is mind bottling.  The expense of trying to test a building like this is obscenely high, if at all possible.  

        Point being, traditional methods of testing/implementing/verifying are not always applicable.    The opportunities and scope vary significantly from project to project; a cookie cutter approach is not reasonable.  Do we need to test every house in Levittown?  No way.  Economies must be built into programs if upgrading multiple similar buildings.  But do we need a trained professional to ensure the post-construction safety of  occupant and property at every single house/building?  Absolutely.

        Further complicating things is the issue of ownership.  How are you going to make every private homeowner in a Levittown execute an energy retrofit?  Not going to happen, and if that type of thing becomes legislated, I'm leaving to go look for a *free* country to live in.  Multifamily, however, presents a unique opportunity because participation in an Association might allow for a market-rate program of price-economized audits and retrofits.  Homeowner associations might be interested participants and good folks to talk with. 

        Lastly, On-bill Recovery Loans in the free market seem to have great potential:  Competition would keep services affordable and will spark innovative ideas related to economizing price structures.  Sound analyses and implementation projects should generate energy savings that would make interest rates extremely palatable, and the avoidance of up-front capital outlay by the end-user is a huge incentive.  I hope these programs grow and are implemented judiciously.

  • Phil,


    Not to belabor the point but what did you mean by "give them powerful tools".  I thought I had you pegged as opposed to the "tools" i.e. computer models, IR cameras, blower doors and the like.  Do you have other essential tools in mind? I understand you may be using the term figuratively. 


    I think David is right, regional differences do matter.   


  • It is evident that there are different housing scenes in different regions.  In much of New England, subdivisions by a single firm are small and scattered, compared to other places I've lived in and visited.  I think most houses were built in different eras, very often as a lone project.  Each needs its own analysis.

    People have been talking past each other here, as a result.  Though I wish it would, I don't know how it'll stop.  With enthusiasm, Phil brings a good idea, both for business results and for overall impact, and cannot be omniscient with respect to such regional differences.

  • Phil,

    You assume too much.  You assume that I work for a program that funds my audits, I don't.  Most of my audits are paid for by the owner, the full amount. 

    I don't guarantee savings.  Do you?  What does that mean anyway, you give them all their money back including the cost of all the improvements they undertook that didn't save as much as you predicted? I stand behind my work though.  If a customer doesn't get anywhere near my predictions a year or 2 later than we work together to find out why.     

    I do agree with you that if I were in a 30,000 unit subdivision with all the same type of house that we could get what we need to know by thoroughly testing just 1 or 2 units but that is extreme example.  Up in the north east where I live our subdivisions are 20-50 homes max and they weren't all built by the same builder.  I have seen the huge subdivisions you describe in Vegas.  Do you routinely test in large subdivisions? 

    And yes, you are right, the big box stores are saving more the then HP contractors in total.  However, on a 1 on 1 basis more is saved by choosing the right items rather than just blanketing everything with products bought from the store. This is particularly true on larger buildings and less so on houses.  In other words, choosing the right things to focus on matters more the bigger the building gets.    In fact your argument leads to a logical conclusion that not only should we not test houses, we should not even audit them.  Rather, we should just post an elaborate and detailed website that covers 90% of what is wrong with most homes and refer people to it when they call. Now THAT is cost effective.  What do you think? 

    Personally, I think people will still want auditors to spell it out for them anyway, even if there was such a website.        

  • Thomas Price,

    I’d like to pick up your doctor analogy; I think there is much in common between us and doctors (except pay). 

    I don’t believe that doctors typically prescribe more tests just to make more money. They know that every test they prescribe has to be paid for and they know generally which ones are covered by insurance and which ones are not.  They prescribe tests because they don’t already know the diagnosis, or they think they know but they want to gain confidence and/or want to rule out other possibilities.  They typically have to balance their need to be 100% confident in their diagnosis with the costs of the tests.  So it is with a good auditor.  She has the tools at her disposal, she uses her experience to form hypotheses about the building, she chooses the tools she needs to gain confidence in, or rule out, those hypotheses, and she has to balance the need for 100% confidence with cost of the audit. 

    For example: You see an acoustic tile ceiling with friction fit fiberglass above it.  No brainer, this is a big air leak.  But what is it worth in energy savings and how does it compare in energy savings with the uninsulated foundation wall of the walk out basement in the same house? An experienced auditor would have some good guesses if they had been faithfully checking energy bills on all their previous retrofits which almost no one has the time for.  I try but I catch less than 5% of my projects because nobody is paying me to look at energy bills a year later.  So what else does that experienced auditor have to cross check his ideas if he doesn’t have any tools?  Nothing.   This is just a simple example.  What about more something a little more nuanced?  How much is sealing behind the baseboards worth vs. air sealing ducts that travel in an inaccessible cold attic?  Intuition tells you they should both be fixed but if the owner wants to phase the work which should they do first? 

    We talk about money being wasted on “needless” tests.  But what about money wasted on needless fixes because the auditor used his intuition but no tools to gain confidence in his recommendations.  What if your work scope includes an item that needs to be fixed on MOST houses but not this one? 

    One thing I will say that has yet to come up explicitly and I believe may be one of the points in favor of the “no tools” proponents.  There is no substitute for time on site.  I find I have to see every nook and cranny before I feel I know the building well enough to start to comment on its energy use. I got burned on some of my earliest projects because I over relied on the output from the tools and didn’t spend enough site time. I cringe when I hear about programs that seek to “streamline” an auditor’s time one site or worse, computer models “so good” that the audit can be conducted by phone.  Not knocking models, they are a tool just like everything else, but there is no model that can substitute for site time.   


    Grant Salmon – I agree 100%.  There is so much more you can do with a blower door than just get the whole building #.  I use it all the time to help confirm that the air sealing I am recommending will: 1- is detailed correctly and, 2- really save energy.  I agree though that most auditors do not use these techniques, some because the programs they work for don’t fund additional tests (back to the doctor analogy) and others because they don’t know these techniques. 

    Have the tools, use judgment and experience in their use.    

  • Thomas,

    I think you are on the right track.  What can we do that still gives us reasonably accurate data yet not use up all the funds on the audit so there are none left for making improvements? I contend, and I can see that some disagree, that auditor experience with a few simple tests can fill in most of the blanks when we cannot conduct all the tests that we would like to.


    I read your article and respectfully disagree.  We do not need to test all multifamily structures in order to be able to do a good job with air sealing.  The late Tony Woods and his colleagues at CANAM came up with an alternative method called ALCAP that was based on blower door tests and completed air sealing on several multifamily high rise buildings.  After a while they abandoned blower door testing in favor of ALCAP because it worked.  I believe that the Zerodraft folks (a spin off from CANAM) use ALCAP as part of their assessment procedures today.     

    One final comment:  Not every auditor knows, but should know, that blower door results at 50 or 75 Pascals don't have an exact translation to air leakage at natural pressures.  In fact, a properly conducted blower door test can be off by as much as a factor of 2 from what a tracer gas test would say (not my words, page 34 in the Minneapolis blower door manual).  Also, the larger the building the harder it is to determine what the blower door number really means at natural pressures, and by extension, what are the potential energy savings.  This is a fact lost on most new auditors because many state and non-profit energy programs treat ACH natural as if it is a hard fact, not what is really is, a highly variable air leakage rate that literally changes with the weather. So, if we are going to get all "scientific" about making sure we test every single building then we have to ask ourselves the question that Colin Genge raised, "what does this all mean?"  If we show with pre and post blower door tests that our air sealing work decreased air leakage by 35% does that mean we can accurately predict what the building will save in heating fuel?  By my experience, the people I’ve talked to, and the research I’ve read probably not.

    I don’t disparage the science or the proper test techniques.  I have several blower doors and use them to test buildings every week but the bottom line is auditor knowledge and experience is the most important tool out there.  All other tools we have come in second.   

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