Air Infiltration

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WindowLooker
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Joined: Tue Jan 03, 2006 5:21 pm

Air Infiltration

#1 Post by WindowLooker » Tue Jan 03, 2006 10:56 pm

I haven't seen this discussed:

Does anyone know why Certainteed windows have the lowest published air infiltration rates (that I have seen) of <.01 cfm for the double hung?

Most other windows, even expensive ones, have rates of around .1 cfm.

I asked certainteed and they didn't have an answer. I am wondering what gives.

It seems like air infiltration one of the most important issues when you live in an area where it is cold and windy.

Window4U (IL)
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Location: Sales and Installation in Chicagoland and Central Illinois

#2 Post by Window4U (IL) » Tue Jan 03, 2006 11:24 pm

I just did a google search and this is what I found published from Certainteed.
The lower the air infiltration value, the more resistant the window is to air leakage. For example, a CertainTeed Bryn Mawr II standard double-hung window lets in just nine one-hundredths of a cubic foot of air per square foot of window area each minute -- so it receives an air infiltration rating of 0.09 CFM/ft2, significantly exceeding the minimum AAMA air infiltration standard of three one hundredths -- 0.300 CFM/ft2.

WindowLooker
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NewCastle

#3 Post by WindowLooker » Wed Jan 04, 2006 12:57 am

I think the numbers I was referring to are for the NewCastle XT, which is the new construction version of the Bryn Mawr II. Seems like the numbers should be identical, though, since they describe the two versions as being cosmetically the same.

According to Certainteed's NewCastle catalog, they have <.01 cfm air infiltration. (The catalog for NewCastle does not seem to be online)

I have looked at the AAMA site to verify, but they don't seem to have air infiltration numbers in their database? Are those numbers commonly available?

Not to mention that I don't see the CT fabricator of Certainteed for the east coast listed at all.

Window4U (IL)
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#4 Post by Window4U (IL) » Wed Jan 04, 2006 8:04 am

That surprises me. I would have thought they would have been the same since they are basically identical.

For the record, I've always had fairly good luck with certainteed, though which factory they come from is a determining factor in final quality. The one thing I have never liked with them is the roll formed screens. Other than that, a decent upper-midgrade window.

WindowLooker
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Swiggle

#5 Post by WindowLooker » Wed Jan 04, 2006 9:41 am

The design seems okay to me, Except that it is bulky and they use Swiggle Seal, at least here.

Pellaman,
How would I be able to choose where the windows come from?

WindowLooker
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Long Island

#6 Post by WindowLooker » Wed Jan 04, 2006 1:23 pm

I am in Long Island, NY. Certainteed said that the fabricator for this area was Viking/Virep, in Connecticut, which also makes some other brands of windows.

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Randy
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#7 Post by Randy » Wed Jan 04, 2006 4:16 pm

The air leakage number is very surprising, give the fact that the Bryn Mawr window does not have interlocking sashes.

FenEx
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#8 Post by FenEx » Wed Jan 04, 2006 5:29 pm

Certainteed does claim an air-infiltration rate of .09... not anywhere close to a .01. As it was stated that it is one of the best in the industry.. it's not even close again as I know of better performers that achieve .02 on double-hungs. The Bryn Mawr II also has a disappointing Design Pressure rating of DP-30... as others have DP-65+. I'd rate it as slightly above the mid-grade window line as well... no better.

WindowLooker
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dp-50

#9 Post by WindowLooker » Wed Jan 04, 2006 9:16 pm

According to the catalog, DP-50 is an option on some sizes of certainteed. Supposedly they add a metal bar(s) in order to meet that. Supposedly you can order DP-50 as an option on some Silverline and Survivor windows too, as well as others I am sure. Not sure if they actually have been independently tested for that though.

FenEx
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Reply

#10 Post by FenEx » Thu Jan 05, 2006 9:13 am

Pellaman7

There might be some grey area in the numbers that we are discussing. For instance the air-infiltration rates and DP ratings will change considerably from double hungs to fixed casements of the same brand. Here's some info directly from Certainteed.com:

"CertainTeed New Castle XT 48" x 80" double-hung window has a tested structural performance of 45.0 PSF. This means that the window has resisted an applied uniform wind load of 45 pounds per square foot. The design pressure and overall grade rating for this window = R30 which is calculated at 2/3 of the tested structural performance (DP = STP x .667) provides a safety factor."

Air Infiltration
"A CertainTeed Bryn Mawr II standard double-hung window lets in just nine one-hundredths of a cubic foot of air per square foot of window area each minute -- so it receives an air infiltration rating of 0.09 CFM/ft2, significantly exceeding the minimum AAMA air infiltration standard of three one hundredths -- 0.300 CFM/ft2."


WindowLooker also made a very good point. Many window manufacturers have upgrade options available for high pressure and coastal areas. I think it's important to note, that because a manufacturer has these options available it does not imply that every window they sell under the same name automatically provides them. The NFRC is a great example of this, each window brand and type has many options available with drastically different performance results.

This is also noted by Certainteed under General Specifications:
"Windows shall be selected by the design professional to meet all applicable local codes. New Castle XTâ„¢ windows meet or exceed AAMA/NWWDA 101/I.S.2-97. Actual performance results vary by style, type of glass, or glass size. These results range from Grade 15 to Grade 70, providing options for applications requiring higher grade ratings."

windowmann2000
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Air infiltration

#11 Post by windowmann2000 » Fri Jan 06, 2006 3:46 pm

Back in the mid 80's Great Lakes had a beautifull brochure showing an air infiltration test of 0.00. I later found out the tested window was completely caulked on the exterior (that was on page nine). A few years later they came out with a premium product called Plygem and they knew they could not get away with as much, so in that brochure they stated their air test was one half of a combined average of some well known wood windows and a couple of vinyl's and if you did the math it was about 0.05 still bogus. A few years later I read a test from Twin City Testing done on a number of vinyls that had been in the real world and they all failed their original test #'s by mamouth proportions. In defense of Great Lakes I might add since I just got done slamming them, their new Premium product line Uniframe is an excellent product-but priced much to high.
Some of Certainteeds test are less than accurate, but the Bryn Mahr is 0.09, not too bad since it doesn't have a interlock, but Ralph Damen the original Great Lakes owner showed me once in his factory how to get much better test without an interlock, what he forgot to mention was after some years in the field this isn't the best idea. Another thing he pointed out to me was the larger the window the better the test. If you look at Fen-Ex's post you'll understand why.
The point to all this is your better off looking at the DP #'s because until they add some serious aging test to get the air test they are far less than accurate. The DP # gives you a better indication as to the products strutural integrity. So windows made by Schuco and other like heavy walled extrusions- Sheerframe, the old Spectus etc are still the ones that rise to the top.

Oberon
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Design Pressure ratings

#12 Post by Oberon » Sun Jan 08, 2006 2:46 pm

Good discussion, I am going to offer a few comments on Design Pressure.

DP ratings are established by testing the window to pressures equal to 1.5 times the DP requirement. In other words, if a window is rated to DP40, then it is actually tested to 60psf. If a window is rated to DP20, then it is tested to 30psf.

One might assume that there is a direct linear correlation between DP rating and windspeed. One might also assume that a DP of 40 is twice as “goodâ€Â￾ as a DP of 20 - or that a DP of 80 must be twice as good as a 40 and four-times better than a 20.

Actually, this isn't the case in the real world.

While a specific DP does equate to a specific windspeed, there isn't a direct linear relationship between increases in windspeed and increases in design pressure. In other words, increasing the DP a certain amount does not result in an equal increase in the window's ability to resist a specific windspeed or pressure.

For example, a window with a lowly DP9 is actually rated for a 60mph wind and it is actually tested at 13.5psf which equates to a windspeed of about 72mph. A rating of DP9 is pretty darn low, but a 60mph wind can be a pretty significant gust.
Imagine that we now look at a window rated to DP15. Sounds darn low and no one in their right mind would want a DP15? Well, 15psf actually equates to about an 80mph wind. Now, as mentioned, the window is actually tested to a level 1.5 times higher than the rating, which for a DP15 equals 22.5psf, and that equals an approximate 95mph windspeed. So while a 15DP doesn't look like much, it really isn't bad at all…and it is probably acceptable for any application – in the right environment.
And btw, exceeding a window’s DP rating does not mean that suddenly the window will explode or come crashing into your home killing everyone inside; it simply means that the "performance values" of the window are rated to a particular pressure. Can windows "fail" when subjected to windspeeds above the rating? Of course they can, but failure generally means cracked glass or warped frames or something similar and not necessarily catastrophic collapse. However, on the flip side, there are very good reasons why hurricane-prone regions are now mandating minimum DP requirements when building new construction or renovating.
While back at the numbers….a design pressure of 45psf actually equates to a windspeed of 135mph while a design pressure of 60psf by comparison equals a windspeed of 155mph – and at the tested pressure of 90psf it is approximately 190mph. What you may now have noticed is that as the DP increases the percentage difference between design pressure and actual windspeed has decreased. In fact, you may also have already noticed that the ratios of the design pressures are the square of the ratios of the wind-speeds.
So while 60psf equals four times 15psf, the equivalent windspeed difference has “onlyâ€Â￾ doubled.

My point being that while DP ratings can be very important, even crucial, in some environments, the idea that a person in an area that rarely or never experiences 100mph wind gusts is worried about the difference between a DP45 versus a DP60 is worrying over something that really isn’t a significant factor in their situation…A window or door with a DP15 or DP20 can be every bit as good – in the correct environment – as a window or door with a DP80.

JScott
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#13 Post by JScott » Sun Jan 08, 2006 8:17 pm

Oberon,
Very good explanation. I have often wondered what the relationships were. In addition, one of my manufacture reps indicated all windows are tested at room temperature or around 70 degrees farenheit. As vinyl expands and contracts the ratings for air and water infiltration are greatly varied by the envirnomental conditions. Do you have any further insight? Thanks.

windowmann2000
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Air infiltration

#14 Post by windowmann2000 » Mon Jan 09, 2006 6:24 pm

Thanks Oberon, good post.

xmurray
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#15 Post by xmurray » Sun Jan 22, 2006 6:57 pm

Unfortunately I made the mistake of assuming all the Certainteed New Castle XT windows would be great, high quality, energy efficient windows when I had 14 sliders put in my house. I live on Long Island near the water and the wind blows right through the tracks on these windows. They even whistle and keep me up at night from the sound and cold air blowing in, even blows my shades around! Seems like a major design flaw to me. The installation is fine and there are no leaks around the frame. All the leaking is from the tracks. From the reading I have now been doing (a little late!) I realize sliders were not the best choice for my area. But my Anderson sliding doors do not leak a drop, so why can't the windows be sealed the same way? I have emailed Certainteed for a solution but I won't hold my breath. One positive note is that I probably won't ever die from carbon monoxide poisoning! If anyone else has had this problem or can suggest a solution please let me know.
Thanks.

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