Air infiltration measurement

[resident1]

I've seen your recommendations that air infiltration should be 0.05 or less.

Is there a standard unit attached to that measurement so that different manufacturers numbers are truly comparing apples to apples? Also, do testing conditions vary sufficiently that the numbers lose meaning without reading the test reports and truly understanding how they were tested?

I've seen this measurement quoted as:
1) cfm / ft2 of frame @ 1.57 psf wind pressure
2) CAM / ft2
3) scfm / ft2

[HomeSealed]

Testing conditions do not vary as long as the test is administered by an ANSI certified lab, like AAMA, Keystone, and NAMI. This ensures that an apples to apples comparison can be made. Most manufacturers publish results tested on a similar sized unit, however from time to time you will see someone try to manipulate that by publishing a rating from a unit that is overly large, which makes the rating sound better. To my knowledge there was a wood window manufacturer or two that have done this in the recent past, but that's about it.

[resident1]

I guess I understand that "scfm" and "cfm / ft2 of frame @ 1.57 psf wind pressure" are the same thing….but still not sure what CAM/ft2 is.

Anyway, your old post below was helpful in interpreting air infiltration numbers!


viewtopic.php?f=1&t=4018&start=0

[Windows on Washington]

I think CAM is another way of someone expressing Cubic - Air - Minute (i.e. CAM).

I haven't seen that previously used, however, if you look at the test results, they show cfm/ft2

[HomeSealed]

I guess I understand that "scfm" and "cfm / ft2 of frame @ 1.57 psf wind pressure" are the same thing….but still not sure what CAM/ft2 is.

Anyway, your old post below was helpful in interpreting air infiltration numbers!


viewtopic.php?f=1&t=4018&start=0

Personally I have actually gained additional perspective on the subject from what it was in that post several years ago. As you read, I had been highly suspect of the tangible benefit of the difference in air infiltration ratings as discussed. This was based on mostly anecdotal evidence including my extensive background installing, selling, and servicing a variety of windows with a wide range of ratings across the board. Since that time, I have had the opportunity to become involved in the building science industry, as well as being educated and certified in that field. I've also had the opportunity to see the results of those differences both in theory, and in the field. Air leakage is a primary factor in in determining the energy efficiency and performance of a home or building, and I do advocate the lowest air infiltration rating possible when it comes to choosing windows or any other such product. Don't get me wrong, it should not be the only aspect looked at and should be weighed appropriately with several other factors, however, it should be considered as an important aspect.

[Windows on Washington]

And knowing is...

[TheWindowNerd]

Cam is used in Canada.

[Guy]

I totally agree with Homesealed. We as installers, salesman, service technicians, and anything else can only believe and support what we've learned over the years. I can straight up say I don't believe half the stuff I promoted ten years ago. I've learned a lot more from the other pros on these boards than any place. We have always collaborated back and forth. I've even threatened the Southern guys that I'm tired of MN Winters and need a job down there. Still thinking about that!!
Air Infiltration can only be measured by the whole house theory or what we call the envelope. I can't tell you how many times I've changed out doors and windows to only set off the CO2 detectors. We change the airflow instantly and can cause bodily harm if not educated properly. While we tighten down the flow in one place means it may be coming hot and heavy through another. The 70's in my eyes brought us the worst craftsmanship of our trades. I don't think we will ever gain back the respect we once had. That's why I changed my theory back in the early 90's. I'm not a salesman anymore! I'm an educator to the consumer. If I can educate my customer enough to make a good logical choice for their home, I'm golden!!

[TheWindowNerd]

Well said Guy>

theWindowNerd