Article Claiming Dual-Pane Windows Are Not Really Beneficial

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GaryB

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Hi - I was planning to order dual pane windows (for my 5er I plan to get) to better insulate from heat/cold and to prevent condensation. But I read the following article (shown below) in the FAQ section of the NuWa website (www.nuwa.com). The main thrust is that true "thermopane" windows don't really exist in the RV industry (although they're often erroneously referred to as that). They claim the existing "dual pane" windows don't have a layer of inert gas between the panes and, therefore, the added insulation benefits are very negligible. I'm guessing it has to do with the difficulty of maintaining a tight seal for the air.? Does anybody have any insight into the validity of this claim, or into the claim/availability of storm windows?? Here's the article.............


We know of no real thermopane window in the RV towable industry. Thermopane is a term being improperly used by some manufacturers and sales people.? What is available is "dual pane" windows, which is two sheets of glass instead of one, however there is no inert gas sealed between the panes as on residential thermopane windows. Don't expect tremendous improvement to insulation value (approx. 0.5 R factor improvement), because the second layer of glass doesn't by itself add that much R factor without the air between the panes. The positive features heard from customers are ?less outside noise penetration? and ?improved insulation?. The negative comments are $1600+ of cost and around 150 lbs of extra weight. Are they worth it? Those who have them will probably say they are. Will they pay for themselves in propane savings? Probably not.

Storm windows provide more insulation value, and are less expensive. But because customers are being led to believe they are buying "thermopane" windows, the storm window popularity has waned. The one downside of storm windows is the need to store them when not in use. And don't expect them to prevent all condensation in extreme temperatures, because of the metal frame used to make the storm window. They prevent outside air ventilation unless removed from the window.
 

Ned

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It sounds like someone trying to sell storm windows for RVs.  I fail to see any advantage of storm windows over dual pane, and several disadavantages.  When in use, they are equivalent to dual pane windows, and when not in use they have to be stored and probably weigh as much or more as dual pane windows.  Dual pane windows do give more insulation than single pane, but how much is hard to say.  I think they're more effective in cold weather than in hot, but reflective tinting, if available, is very effective in hot weather.

No, dual pane is not thermopane, but the air gap does offer some insulating value and just having twice as much glass thickness does also.
 

John From Detroit

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The information the sales page provides is the normal combination of fact and fertilizer.

Though different gasses do have different specific heat and different properties I very strongly suspect that the difference between inert gas and regular air is not really worth talking about

What does make a big difference is the amount of air between the windows

AIR (the kind we breath) is not really a very good conductor of heat, the thermopane windows, and storm windows, are based on that fact, however it can move and it can carry heat.  Inert gas, well, the difference is how well it carries, however as noted the difference is not that great.

With dual pane or thermo pane windows you have a small quantity of air which is well sealed between the glass it can not move around well, and thus you are looking at the insulating properties, which are good,  If you have a LOT of air then it can get rolling and transport heat, this would be the case with storm windows.

Thus, I would say there is more fertilizer in that ad than fact.
 

Ron

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Interesting but I do not recall ever seeing or hearing any reference to Thermopane windows i by any manufacturer or even a salesman when discussing windows  RV/s.  Dual pane windows yes but Thermopane never.  We have dual pane windows and I do believe they are better than the single pane windows we had in previous motorhomes.  How much better I would not even try to guess at.  If an RV was not originally constructed with dual pane windows then I would not think changing over would be that beneficial considering cost involved.
 

Tinner

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Holland, Texas
Ron,
One of the options I have on my '03 Cardinal 36XLE is Thermo-Pane windows.  You got me to wondering so I pulled out the sales broscher for 2003 Cardinals and they are listed as Thermo-pane windows.  The thermal refers to the insulating value of the captured air I'm sure.  We are going to add film to ours this fall to help out in the summer sun too.  Have a good one.

Gun Control --- "Being Able To Hit One's Target"
Ronnie
 

Ned

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See http://science.enotes.com/science-fact-finder/metals-other-materials/who-invented-thermopane-glass for a brief definition of thermopane glass.  Technically, if the dual pane windows we are used to seeing are bonded together and not just two sheets of glass in the frame, they fall under the definition of thermopane.  The space between can be air or an inert gas.
 

Ray D

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My information on this is a bit dated, but may be helpful.

Back when I knew what I was talking about, Thermo Pane was a brand name for windows with two or three panes of glass and a sealed air gap between them. There were several brands, back in the early days. Thermo Pane may have been reduced to generic, since them, but they fought that diligently.

A later event was the introduction of Argon gas, between the panes touted as having a higher R factor. It was also quite a bit more effective.

My company advised people at that time that the windows would never pay for themselves in savings on heating costs. We advised that they were "cost effective" anyway, as a comfort enhancing product. It is much more "comfortable" sitting next to insulated glass, than a simple single glass window. It is a warmer exposure in the winter and cooler in the summer.

I have recent experience with the difference. Our previous Motorhome had single pane glass, and it was uncomfortable sitting next to the glass, particularly in cold weather. Our new motorhome came with insulated glass, and that was one of the issues I considered important, while shopping.

The payoff comes in as a square footage of use issue. If you have a window that is 4 ft. long and it is drafty, "uncomfortable," to sit within 2 feet of it, then you have lost 8 square feet of living space. Or, you can put it another way - If you can buy an additional 8 square feet of living space with insulated glass: What is the cost of the glass, (window) vs. the value of 8 square feet of living space.

To get the answer, divide the cost of your RV by the number of square feet of living space, and you have the value of each square foot. Should tell you whether you want the insulated glass, or not.

For my RV, the living space is a little over $400 per square foot. It came with insulated glass. However, if I had to determine whether it was "worth it" or not, the 4 ft. window would have to cost me less than $3,200. The conclusion is "BUY!"

Hope I explained my opinion clearly.

Ray D

Ediited: The same logic applies to awnings. If I am sitting next to a sunny window, on a hot day, I am uncomfortable. Not only that, but my AC is struggling to cool the entire unit. So, I put out the awning and suddenly my AC is more effective and I can sit closer to the window and enjoy the view. My unit does not have awnings on the smaller windows. Consequently, on a hot day I cannot make that comfortable without drawing the blinds, which obscures the view. I'll be getting awnings on those windows, soon. Saving money? No, spending money! Buying more space to enjoy without trading up to a larger motorhome! It's a bargain!
 

HittinDaRoad

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Jan 15, 2006
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We chose the dual-pane windows in our motorhome when we ordered and we love them. They keep out so much of the noise when closed and they don't steam up like the windshield does.? We changed our windshield curtains and put in thermal drapes and that is a big improvement also.?

We do not regret our decision to go with the dual-pane windows at all - they were not advertised as thermopane windows -
 

Shayne

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Having sold building products for years and attending many window manufacturers, There definately is a difference on todays market between welded windows, dual panes, and Thermopane.  Dual pane can be any assortment of welded, glued, Storm type or insulated glass.  Thermo has an Vaccuum , inert gas, and tints with 2 panes of glass held together by mastic in most cases and can even have metal or plastic/vinyl inserted. Welded may also have inert glass between.  IN MOST cases Thermo units are at least 1/2" over thickness to generally 1" thickness.  Triple glazed has 2 single strength glass on the inside with 1 Double strength glass on the O/S pane with inert gasses within.  Most Thermo glasses are 5/8" thick to 3/4" thickness outside dementions.  Thermo in the build trades eyes would be really add a tremendous amount of weight to an RV.  MOst of the RVs I've seen, and thats been abundle since the late 60's when I began selling them, have either the welded glass or Dual pane.  There may b e a few, very few, Thermo units in RVs  Best I can offer for an explanation in laymans terms.  Hope this helps.
 

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