When the Pella triple pane windows get a best U-Value of 0.28 and the other triple pane windows get as low as 0.10 - what is left to say?

There is something going on in the design of the Pella triple panes that they are not achieving the same energy values of other triple panes. I believe it is due to design, glass thickness, sealing properties, etc.

Lee, the link to the Cardinal glass website shows the difference in performance between a triple pane with a a 1" IG versus a triple pane with a 1 3/8" IG. A 1 3/8" triple pane IG provides "true" triple pane performance just like a 3/4" double pane IG provides "true" double pane performance.

Posted By EnerLux on 13 Mar 2012 06:37 PM
Lee, the link to the Cardinal glass website shows the difference in performance between a triple pane with a a 1" IG versus a triple pane with a 1 3/8" IG. A 1 3/8" triple pane IG provides "true" triple pane performance...

...unless you are restricted to high-altitude, air-filled windows (which I am) in which case the optimum gap between glazings is about 16 mm rather than 12.7 mm for Cardinal Glass LoE-179 Triple Pane (surfaces #2 and #5) windows (http://www.cardinalcorp.com/wp-cont...ochure.pdf).  (I assume that the newer Loe-180 would perform similarly.)  Then you have to come up with a new definition for "'true' triple pane windows" with "'true' triple pane performance."  I would suggest leaving the word "true" out and just define the window layout and performance specs more precisely.  Let the buyer determine what is truth and beauty in his/her windows.

Posted By Lbear on 13 Mar 2012 05:53 PM

When the Pella triple pane windows get a best U-Value of 0.28 and the other triple pane windows get as low as 0.10 - what is left to say?

I suggest you buy whatever windows meet your criteria, and let others do the same, since others may have more complex and comprehensive criteria that they use to evaluate windows.

I spoke to an engineer who designs many award winning passive homes and gave him my specifications. He stated that going with a super high SHGC on the southern windows will definitely overheat the home. I will go with a 0.49 SHGC on the southern exposure vs. the 0.62 option, as I do NOT want to overheat the home.

Full Disclosure- my company distributes SeriousWindows products in eastern Canada.
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In defence of SeriousWindows, and their use of suspended coated film and Heat Mirror films. Like any product their are good and bad manufacturers, saying that heat mirror is bad because of one company's problems, is like saying that all double windows are bad, because the seals sometimes fail.
The test of any glass or window manufacturer is the examination of product installed 15 or 20 years ago.

SeriousWindows (formerly Alpen) has a 30 year history of producing in their own factories glass with suspended coated films and Heat mirror.
Here is a sample of major projects that date back to 1981, and all in excellent condition.

HOLY CROSS ENERGY, Glenwood Springs, Colorado ,1981
NEW YORK HISTORICAL SOCIETY New York, NY, 1982
BOEING MUSEUM OF FLIGHT, 1984.
HOTEL TROPICANNA II – LAS VEGAS 1985
COLORADO STATE SERVICES BUILDING, Grand Junction, CO (1982)
SMITHSONIAN NATIONAL PORTRAIT GALLERY Washington, DC, 1991
SMITHSONIAN FREER GALLERY, Washington, DC, 1992
NEWARK AIRPORT (Monorail Terminals) 1992
NATIONAL AUDUBON HEADQUARTERS, New York, NY 1995
SAN JOSE CONVENTION CENTER – California, 1995
VIRGINIA AIR & SPACE MUSEUM, Hampton, VA 1997
BOULDER, COLORADO LIBRARY, 1998
GUGGENHEIM-MANHEIM – LAS VEGAS, 2001
SMITHSONIAN NATIONAL MUSEUM OF NATURAL HISTORY Washington, DC 2002

I believe that many forums have too much opinion based information on them. If you want to see the differences between certain window companies all you need to do is go to the National Fenestration Rating Councils website and see first hand. http://www.nfrc.org/ Intus and Serious blow away Pella when you look at there numbers. The biggest advantage to using a window not sold at your LUMBER-MARTS is that you have much better seals. This is the most important part of any window or door. That is where you really see a difference. Unfortunately most American window companies have not put as much engineering into the seals. Thus the lower price. Attention to detail does cost you. The American made window companys have not had to focus on performance like they are now. It has always been the name that would sell in the past. They are going to need to make major changes soon as the marketplace becomes more educated on the value of performance. Blower door test I believe will be mandatory before you close on a home in the future. This will be a game changer for all window and door companies. Looks alone are not enough for the marketplace anymore.