Air infiltration, PG and DP rating question.

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rebar
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Air infiltration, PG and DP rating question.

#1 Post by rebar »

Evening folks..

In my opinion, reducing air infiltration in a structure is just as important as a good R value, so that applies to windows as well, imo.
I'm in the middle of nowhere close to Millersburg Iowa on a hilltop surrounded by corn fields. It's windy, and in a heating dominant climate zone #5.

My question is regarding air infiltration ratings. I found information stating DP or a high "design pressure" number indicates less air infiltration. But also found that the PG "Performance Grade" rating is more accurate. But Ive also read here on the forum to look for AL numbers.

Which of these ratings should I be looking at to determine how tight the window is?

Thanks
Last edited by rebar on Sat Apr 27, 2024 8:44 am, edited 1 time in total.

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toddinmn
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Re: Air infiltration, PG and DP rating question.

#2 Post by toddinmn »

I’d say both. A window can have a high DP/PG rating and high air infiltration rating.

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TheWindowNerd
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Re: Air infiltration, PG and DP rating question.

#3 Post by TheWindowNerd »

AI is the quickest and simpelist to find.
I suggest .03 or less.

rebar
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Location: Iowa City

Re: Air infiltration, PG and DP rating question.

#4 Post by rebar »

toddinmn wrote: Fri Apr 26, 2024 10:59 pm I’d say both. A window can have a high DP/PG rating and high air infiltration rating.

Thanks toddinmn.

Yes Ive read a DP rating can ignore air leakage because it only has to meet two out of three components of the testing. Air infiltration, water, and structural loading. But a PG Rating must include all three components. Why the industry would combine structural loading with air and water leakage rates, and then allow loop holes in the reporting is odd.

Ricknez
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Re: Air infiltration, PG and DP rating question.

#5 Post by Ricknez »

The top windows all seem to have an air infiltration rating of .05 or under on double hungs and a .02 or lower on casements.

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TheWindowNerd
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Re: Air infiltration, PG and DP rating question.

#6 Post by TheWindowNerd »

Rick, by top windows what are you including?
Clearly Pella, Marvin or AW any series, do not have a window .05 or less in DH.
We sell and install all three to my "wood snobs", they are made aware of the AL issue.
wayne theWindowNerd

Ricknez
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Re: Air infiltration, PG and DP rating question.

#7 Post by Ricknez »

TheWindowNerd wrote: Sun Apr 28, 2024 6:54 pm Rick, by top windows what are you including?
Clearly Pella, Marvin or AW any series, do not have a window .05 or less in DH.
We sell and install all three to my "wood snobs", they are made aware of the AL issue.
wayne theWindowNerd
Most of the top vinyl offerings will have air infiltration ratings of .05 or lower.

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HomeSealed
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Re: Air infiltration, PG and DP rating question.

#8 Post by HomeSealed »

@rebar, these are two completely different ratings/tests and each has its own function.

A DP test is essentially testing the strength of the window, as in how much pressure is applied (simulating windspeed) before it fails. Excellent indicator of strength.

An air infiltration test is not adding any other forces or pressure on the window, its simply the window as constructed, tested at a 25mph windspeed.

Both are important for obvious reasons, and you are absolutely correct in stating the importance of "air-tightness" as it applies to making your home more energy efficient.

While its possible to have a home that is "too tight" in that there is not enough air exchange occuring for optimal indoor air quality, the goal is to get the home and its components sealed as tightly as possible from all of the "uncontrolled" means of air exchange (ie: leaky windows, etc) in favor of controlled, consistent, mechanical exchange.

rebar
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Location: Iowa City

Re: Air infiltration, PG and DP rating question.

#9 Post by rebar »

HomeSealed wrote: Mon Apr 29, 2024 1:20 pm @rebar, these are two completely different ratings/tests and each has its own function.

A DP test is essentially testing the strength of the window, as in how much pressure is applied (simulating windspeed) before it fails. Excellent indicator of strength.

An air infiltration test is not adding any other forces or pressure on the window, its simply the window as constructed, tested at a 25mph windspeed.

Both are important for obvious reasons, and you are absolutely correct in stating the importance of "air-tightness" as it applies to making your home more energy efficient.

While its possible to have a home that is "too tight" in that there is not enough air exchange occuring for optimal indoor air quality, the goal is to get the home and its components sealed as tightly as possible from all of the "uncontrolled" means of air exchange (ie: leaky windows, etc) in favor of controlled, consistent, mechanical exchange.
Thanks HomeSealed.

Not according to what Ive read.
DP and PG ratings both test air infiltration, water, and structural loading.
But a DP rating only had to meet two out of three components of the testing. PG Ratings will be given to products that meet all three elements of testing.

Apparently AL ratings aren't always given and DP or PG ratings are the only way to know AL. Window manufacturers who voluntarily decide to test their windows according to NFRC labeling requirements must report U-factor, SHGC, and VT, but they aren't required to report air leakage. So if a manufacturer doesn't report AL, that probably means the numbers are subpar anyway imo.

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HomeSealed
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Re: Air infiltration, PG and DP rating question.

#10 Post by HomeSealed »

rebar, you are mixing and matching some information here.

I've explained the testing of DP and AI above. Two separate tests, two separate ratings. Anyone claiming otherwise is misinformed.
To be certified by ANSI/AAMA (gold label, silver label, etc) the window must be tested structurally. If you can get your hands on a structural test report for a product that you are considering (some dealers and manufacturers are more forthcoming than others), it would connect the dots for you on this if you don't want to take my word for it.

With regard to the NFRC, they have nothing to do with the structural testing. The NFRC has a pass/fail air infiltration qualifier at 0.3cfm which is atrocious. When air infiltration is shown on the sticker, it is listed as <0.3 as such.

Why is this? IMO, it is due to the big $$$ manufacturers which typically are not offering the "tightest" windows in the world, and their attempt to keep their products from being exposed as subpar. Unfortunately, like any industry, there is plenty of politics that exists in the window business.

So to clarify, any window that is tested and certified structurally has an air infiltration rating. This is independent from DP or PG. If you are looking to ensure that you get an air tight window, the Air Infiltration rating is what you will want to focus on.

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toddinmn
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Re: Air infiltration, PG and DP rating question.

#11 Post by toddinmn »

My theory is that smaller boutique companies
Exploited this as a sales tool. Until the testing is more standardized and more clear cut It is just that.
The way it is now no consumer can figure this out on their own with actual data.

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HomeSealed
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Re: Air infiltration, PG and DP rating question.

#12 Post by HomeSealed »

toddinmn wrote: Tue Apr 30, 2024 10:54 pm My theory is that smaller boutique companies
Exploited this as a sales tool. Until the testing is more standardized and more clear cut It is just that.
The way it is now no consumer can figure this out on their own with actual data.
I once held a similar belief Todd, and then as I was able to work with some of the products that have the superior ratings, I saw and felt a tangible difference in design, quality, and the service calls that I received for drafts, etc dropped off a cliff as well. This led me to research the testing, the certification process, and even viewed some testing to understand it all... and this was all before air leakage was widely known and accepted as one of the primary determining factors of the overall efficiency of a building.

Regarding the testing, it is standardized. What makes it seem like it's not is companies that withhold it, or that promote data from testing uncertified sizes. If literally nothing changed with the current testing, but the NFRC began requiring the actual certified AI rating tested on the product to be used on the sticker instead of the waste of space "<0.3", this would all make perfect sense to the average homeowner, I'm sure that you'd agree... That, or having the structural testing results on its own, larger, "gold label" for comparison purposes.

Again, the issue here is information being WITHHELD and/or misleading information given (ie: uncertified AI ratings), and NOT the fact that some companies with excellent, certified ratings promote them.

I know that you love my car analogies, think about if car manufacturers could:
1) choose to put the certified MPG on the sticker or not
2) could use an non-standard test result and publish that on the sticker as long as they don't claim it to be certified

What we do have, is something like : Everyone has a pass/fail rating of some ridiculously bad fuel efficiency number, like >10mpg on the sticker, even though we know that some vehicles get much, much better MPG than others.

Your last statement: "The way it is now no consumer can figure this out on their own with actual data." is not entirely off-base, only the party that you hold responsible is IMO.
If I were a consumer, I'd have some confidence an AI rating promoted in a brochure (as long as it states the correct type of configuration, ie: a DH not a PW). OTOH, if a sales rep is telling me a good rating that is not published (as we hear in this forum from time to time), while not convenient, I'd be looking for a structural test report to verify that.
Last edited by HomeSealed on Wed May 01, 2024 4:44 pm, edited 1 time in total.

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toddinmn
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Re: Air infiltration, PG and DP rating question.

#13 Post by toddinmn »

The test is standardized, the window size not so much.
Personally I would prefer the companies to show the actual and current test results . Don’t need pictures of soda cans or balloons. Is there anything stopping a manufacturer from putting the actual air number on the NFRC sticker? Air testing was widely know

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toddinmn
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Re: Air infiltration, PG and DP rating question.

#14 Post by toddinmn »

toddinmn wrote: Wed May 01, 2024 10:57 pm The test is standardized, the window size not so much.
Personally I would prefer the companies to show the actual and current test results . Don’t need pictures of soda cans or balloons. Is there anything stopping a manufacturer from putting the actual air number on the NFRC sticker? Air testing / leakage was widely know 30 years ago I remember the first house I worked on that had a blower door test . We installed Pella Proline’s in the house and it was deemed too tight and a continuous bath fan was installed to remedy it.

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HomeSealed
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Re: Air infiltration, PG and DP rating question.

#15 Post by HomeSealed »

toddinmn wrote: Wed May 01, 2024 10:57 pm The test is standardized, the window size not so much.
Yes it is. I've explained several times Todd, the test has a required gateway size.
toddinmn wrote: Wed May 01, 2024 10:57 pm Personally I would prefer the companies to show the actual and current test results . Don’t need pictures of soda cans or balloons. Is there anything stopping a manufacturer from putting the actual air number on the NFRC sticker?
Whether or not it comes with a picture of balloon or soda can, the result data is given, as well as the test specifications, window size, etc in many cases. Not sure what else you are looking for here Todd. Most people find a visual aid like balloons or gallon jugs helpful to understand the quantity of air that is actually represented by those ratings-- especially when provided along side them. I agree that it could be misleading if the visual were used without any data (maybe like a picture of a kid standing on a long piece of fiberglass for instance), but I can't say I've ever seen anyone publish balloons or soda cans in their brochures without the data along with it.

Regarding the sticker, as a matter of fact yes. Unless something has changed, to my knowledge the AI rating is optional to show, however it is the NFRC's pass/fail <0.3 rating that is shown if desired. You cannot put the actual tested rating... and IMO that is due to the politics that I alluded to earlier.

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