Anderson, Pella and Marvin Window Comparisons
DEAR TIM: I was looking at your web page for some information on windows, specifically a comparison between Anderson casement windows and Pella. I thought I had a handle on the basics of double pane, gas-sealed, low-e, high-efficiency thermo-pane windows, but from what I've seen of Pella windows, they're not sealed at all. To me, this blows the whole "sealed = high efficiency" thing out of the water. How can Pella boast high/higher efficiency, when all they seem to do is provide two unsealed panes of glass? Am I missing something?
I know some folks swear by Pella, but to me, Anderson or Marvin seem to be a better product because their windows actually provide a sealed-space, which I thought insulated better. I like Pella's casement product from a standpoint of no chance of seal failures and fogging, plus the in-between mini-blinds, but I'm not convinced that they actually deliver the same level of efficiency. Vic Johansen, Cincinnati, OH
DEAR VIC: A good friend of mine who happens to be a CPA and a former mentor of mine taught me several years ago that numbers don't lie. When you couple this fact with independent certification numbers assigned by testing laboratories to the different windows, you have a clear-cut method of scientifically choosing top-quality windows.
The brands you speak of all are great companies and the last time I checked they all carried independent certification from the National Fennestration Rating Council (NFRC) with respect to the R-values of the windows and specifically the glazed or glass portion of the window.
Pella's window design for years has used a removable pane of glass that had a built-in gasket. This gasket, believe it or not, produced a seal that could rival those of the insulated glass you see in other windows. The latest version of Pella that I saw at the International Builders Show had insulated glass married with a third glazed panel.
I believe if you really compare apples to apples you will discover the overall energy efficiency of the windows is nearly the same. That, after all, is what you are looking for. You should also pay attention to any rating numbers with respect to the R-value of the glass when measured both at the center of the glass and at the edges. This R-value can vary significantly in different windows.
Author's Notes: After this column was published, it was discovered by a Pella window consultant named Paul Brand. He emailed the following comments to me:
" My name is Paul Brand and I am a window consultant for Pella Windows and Doors. I just read an article off of your website that addressed an inquiry regarding a comparison between Andersen and Pella windows. The writer was curious as to why Pella would not manufacture " double pane, gas-sealed, low-e, high-efficiency thermo-pane windows" . In fact, Pella does manufacture such a window.
I may be making an assumption here, but I believe the window he may have been looking at is part of our Designer Series product line. This particular window is available with a variety of glazing options including a clear single glazed exterior pane with a hinged interior clear glass panel. Obviously, this glazing option would not be a suitable choice for homes located in the northern half of the United States. Might I suggest looking at the same product line but have the unit(s) specified with our 5/8" InsulShield insulating glass with a clear hinged panel. By selecting this glazing option the homeowner can expect to see industry leading U-values and an outside sound reduction of up to 80%. In addition, the Designer Series product line is the only product available where the homeowner can select from 25 different "between-the-glass" pleated shade / blind options."
Window Consultant / Contractor Sales
Pella Windows & Doors - T.C., Inc.