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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Clients love to see deployment of a half dozen strategically placed blower doors, all tied into a laptop that controls all the doors as you pressurized a building.   I always thought this was not necessary after rehabbing 10,000 units of MF housing since they all leak in the same places.  But as one savvy consultant told me "If you wanna make the dough you gotta put on the show" and since you can measure pascals as you tighten even a large building, its verifiable as you go along = and your deliverable is a printout showing reduced ACH and an invoice.  Prep is a huge pain and time consuming but a gullible customer convinced in the value will pay for it.  Plus how the heck else will you amortized your equipment? 

That's pretty much what I was afraid was the reason.


I'm into saving energy, not taking advantage of anyone.  After your description, I'm even less of a fan of blower doors.  I'd suggest that utility bills are a much better metric for measuring efficacy.

That is disturbing. People would be better off investing in air sealing and more efficient appliances. Instead of paying for what boils down to an opinion from someone who has magically transformed into an expert in 6 days. Forget the audit air seal, insulate, upgrade appliances. this is how you truly save money

Would you guys recommend perform a blower door on a single family home?

"I'm into saving energy, not taking advantage of anyone"

Air changes and moisture management are important to the residents and the building.

In systems, what you do often is not all you do.

Agreed, but that has more to do with testing out.

Please say more about that, when you have nothing else to do.

I guess what I'm trying to get at is that most of the homes I have tested are way over the BAS.  Running a blower door test does help to quantify things, but we already know that air sealing is a priority.  It is true that we want to make sure that we don't cause problems for combustion appliances (which we can do without a blower door test) and we want to make sure that the IAQ is at a sufficient level after the air sealing is completed.  

What I worry about is taking money from people to run a blower door test that tells them that they need to do air sealing, and then they don't do it because they've used that money for a test that wasn't really necessary to give them that analysis.  Not everybody has hundred dollar bills to shell out so easily.  I think there may be other ways to convince people that it is necessary.  Any fan that creates a pressure difference can also move smoke through cracks in the pressure boundary, without such a big expense.  I'd rather spend money on a thermal camera and pinpoint areas that need attention.  Quantifying the leakage is cool, but someone has to pay for it.  

Also, once you've precisely quantified the infiltration of a home with a blower door test, in order to calculate a savings you have to guess at what your target reduction is.  A chain is only as strong as it's weakest link, so two guesses are practically as good as one.

In multifamily, we're required to add continuous ventilation in most cases anyway, to meet ASHRAE standards, so making a home too tight is impossible. 

To me, it seems like doctors who prescribe expensive tests to make more money for the industry, when they already know the best therapy.  This is my impression as a novice and should be taken for what it is.  I'm open to other opinions.

First of all, the rest of us are trying to have an adult conversation here. Please take the hyperbole someplace else...

But, to respond to the one substantive comment; If you aren't going to test, then it would be dumb to guarantee results. That is certainly true.

So, don't guarantee?? Or, maybe we'd all be better learning enough to make reasonable predictions. Some of us are trying to learn how to make real, accurate predictions, based on measured building behavior.

The rest of the people posting on this thread seem pretty darn sure that testing doesn't tell them anything they didn't already know. If they have already tested so many buildings that they have evidence to back up that assertion, I can repsect it. (But I'd sure like to see that evidence -- as would the clients depending on their judgement.)

I, on the other hand, have learned my lesson about making assumptions. Take two buildings of the several hundred I have assessed -- both are two stories tall, wood frame, truss-attic construction in a heating-dominant climate. Both sit on a monster crawl space, have tons of holes into the attic and an all-atmospheric boiler room. One (a 50 unit building) tested at 85,000 CFM50. The 38 unit building looked essentially identical -- but it tested out at 23,000 CFM50.

Without that "dog and pony show" I'd have grossly undersold the results in the 50 unit. The 38 unit -- I got nothing to sell. I can live with delivering more than promised to the guy that owns the 50 unit.

But telling that 38-unit owner that those holes into the attic means something? That the crawl space is a problem? Those assumptions are false. They just aren't true. But, if you don't measure, you don't know that.

But I suppose ignorance is bliss...


I get the feeling that where you are coming from and where Phil is going make the difference you find irritating.  What has worked and what may need to happen often differ.

I've been on both sides of the fence here.  Have I run blower door tests during audits on simple houses where I already knew what I was looking for?  Absolutely.  If you are called out by a customer in a market-rate setting and you don't run a blower door, you are not providing the energy auditing services that you sold.  And at the least, you need to know the BAS.

That said, this scenario is the exception and not the rule.  Beyond the ability to quantify infiltration, a blower door is the most powerful diagnostic tool that I have come across.  Anybody can run a blower door test to put a number on ACH rates.  Not everybody that can do this test uses the tool to diagnose air leakage pathways properly and to pin-point areas in need of attention.  Many single family homes, and even more multi-family buildings, have airflow networks so complex that even the brightest auditors would be baffled as to the true pressure relationships within the building.  A good building analyst can usually get to the bottom of it with a blower door and a few manometers.

Anybody can use a blower door to tell you something you already know.  The good ones can use the tool to gain an understanding of things they didn't already know.

Anybody can use a blower door to tell you something you already know.  The good ones can use the tool to gain an understanding of things they didn't already know.


Ive followed this thread through the last 20 posts.  These two sentences SAY IT ALL AND SUM IT UP IN those sentences.



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