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How are you finding leaks of warm air exfiltration at the leeward side of the house in winds, at the upper areas of house from stack effect, and at areas of the house where there exists a neutral pressure plane with no air leakage in or out. How do you find air leaks when indoor and outdoor temps are the same? It has been my experience that to find all air leakage with IR, you need the blower door to suck cold/hot air(depends which climate you live in) and make all leaks visible to the IR.

BTW, when I trained to be a US certified energy auditor (1981- Cornerstones School of Building, Brunswick, ME), there was a gent from a Chicago company (Potential Energy Incorporated) whose company was using IR with blower door to find air leaks…and that was 1981!!!


Throw in low delta T situations where a blower door would show a better IR signature where you might not even have one without.

Some say people doing energy audits without an IR camera are 1/2 blind, I believe the other way around holds true as well.

1981? Did that guy wheel that thing in on flat bed truck? I have seen the systems from the late 80’s and they were on a dolly.


It was probably a really big home.

The engineer we used in 1980 to scan some of the houses we blew with insulation had an AGA Thermovision 700 series unit. It was big compared to today and only gave a fuzzy black and white image.

It probably weighed 25 lbs. The front with a 4x4 inch screen was about 5"x12" with a depth of 12-14" that was supported by a chest/shoulder brace. The IR sensing device was super-cooled with liquid nitrogen before imaging began.

I couldn’t agree with you more! One thing I would like to add, as the consumer becomes educated through all this they will expect a certain standard of measurement.

This is the important factor I think most miss

Brian, aside from all the jargon, here is something that you have to realize, in our area. I have never seen a house (new or old) that had less than 15 ACH. No one, around here, air seals. A blower door is usually not needed. I just turn on the bathroom and stove vents and turn on the clothes dryer to air fluff and see many areas of infiltration. When there is no delta T (usually only for a month or two in spring and summer) I use a smoke pen and fogger. It does n’t take much to find air leaks when they are so many and when you are experienced with where to look, given the common building techniques in this area.

As I have stated, most customers don’t want an detailed, formal, quantitative audit. They want to know where the problems are, how to prioritize and fix them and where to find professionals who know how to fix them properly.

Also, many HVAC people around here are a joke and don’t know the proper way to install high efficiency furnaces (no combustion air intakes run). Doesn’t take a genius to call this out and save them 10% efficiency on the heating gas costs.

Hope this helps;

Check out David Valley’s blog over at Linked-In in regards to the use of blower doors.

I would particularly pay attention to the comments from:

L. Terry Clausing, P.E.
BPI Certified Building Analyst & Envelop Proctor/Instructor
ASNT Certified NDT Level III Thermal Infrared Thermography


Posted there. Thanks for the heads-up, Linus.

Don’t you just love it when P.E.'s speak down to us poor, lowly home inspectors? :mrgreen:

I don’t feel he was speaking down to anyone. His comments are on point!! Sorry Will, but your posts here and over at LinkedIn shows your ignorance on the subject of blower doors. On that thread you indicated that you have certifications from BPI and that you have done comparisons with/with-out the Blower Door per BPI Standards.

So, just to be clear…Are you a BPI Certified Building Analyst and do you own a Blower Door?


Can you take this course and then take the BPI exam without take the BPI course?

Yes, You need a few study guides and you’ll do fine.
Saturn Energy Auditor Field Guide
Residential Energy
Building Analyst Field Training Video

Why spend all your money on certification and be an out of work building analyst when you can do it for a few hundred $$$.


Linus is 100% correct on those resources, you will have a very good shot at passing the exam with those. However, you are required to do field audits, and that is where you can run in to issues. A lot of the field auditors/proctors for BPI are super swamped right now. They also know they can sometimes charge whatever they want to do your field exams. I have found it is just better to go through a certified BPI training facility that includes the BPI exam and field audits right in their training.

Training materials + exam fee + field audits could be a lot more than $1595 (average price through out the country). If you are in AZ there is a local company here that does it for $875 (Peter did his training there) and if you are an AZ business/resident APS will kick you back 50% of that.

Clean Edison is nationwide and a little birdy told me they will soon have a BPI/Resnet all in one class. Here is a link to all their current BPI offerings throughout the country.


Clean Edison will be at studios all next week. It’s all going online in HD through

Anyone who comments on blower doors that does not own one and use it daily clearly does not know what they’re talking about.


I went through the Energy Audit course (and passed the test, yay!). It is a good starter to doing energy audits, but not even close to being enough training to do an evaluation properly in my opinion. Auditors have to realize that being a good energy auditor goes way beyond a good training course. It takes countless hours of research on products and building science just to scratch the surface of the energy field. I have personally done over 500 energy evaluations, and consider myself very good at what I do, but I also realize that I still have alot to learn. I believe continuing education is extremely important in the energy field. You can spend hundreds of hours learning something, then only to find out there has been 10 new things that have been developed since you started. If there has been one main thing i have learned it is that just when you think you have learned it all…its time to start all over again! I guess thats why I love what I do. There, thats my 2 cents worth.

I thought I would add this. This is from I job I completed yesterday and here is what we did.
Replace weather stripping and sweeps on three doors
Treat attic hatch and insulate with 4’’ HI-R foam
Repair holes in bathroom walls, effected pressure
Air seal all penetrations in attic
Open blow cellulose insulation to R-45 1200 Sqr. FT
Dense pack side wall overhang, Garrison style home to 8’’ 325 SQR FT
Replace T-Stat with digital
Replace bathroom fan/light with Panasonic 110 CFM and hard pipe through the roof with insulation and new roof vent.
Replace rotted chimney clean out door
Replace rotted fascia and soffit, 11 Feet
Hard pipe dryer vent with new hood

Pre blower door test 1700 CFM@50
Post blower door test 1380 CFM@50
Conducted pre and post CAZ test
Conduct boiler efficiency test pre and post retrofit

Total cost of retrofit $3086.00
Energy audit with thermal imaging 500.00

Total cost of job 3586.00

All of this is pretty funny. Secretaries are now getting LEED designations, just by working for firms who do the designs, because with LEED, one needs to have participated in the design process.

Many governmental agencies do not subscribe to either BPI or RESNET. The energy engineers, who specialize in this from an auditing and engineering (many are PEs and all are at least mechanical or electrical engineers with college courses in the latest in energy issues and design considerations) state emphatically that blower door tests are typically not necessary.

I wonder how much of this is being driven by the manufacturers and the auditors, as opposed to sound practices. Measuring the efficiency of a building is a far cry from measuting the energy efficiency of a single piece of equipment. With literally thousands of variables, must truly believe that all of this is a best guess.


What will the homeowner’s return on investment be? $3800 in cost versus how much in energy savings over the cost of a year?

5 years?

Many homeowners smly do not have the $3800 on hand. They will need to phase in the repairs over time. Perhaps two years or more…

What do you show them and how do you quantify it?

I have a relative that received a “free” energy audit, a “free” new HE furnace, “free” new insulation, “free” new windows thanks to all you generous taxpayers.

Wake up people.