Hi.

I am needing to replace a full-view exterior door due to termite damage and I was considering getting an argon-filled insert in my unit. It seems as these units provide about double the R-value of a standard, low-e, double-paned unit.

However, I was told by someone at a home improvement store that the fill-material is more dense than air and will completely leak out within five years.

If that is the case, it would seem to neutralize any performance benefit over its lifetime based on cost.


Can anyone verify if this is true?


Thanks in advance.

 

First, it's highly inaccurate when window companies advertise the r-value of their windows or of the glass IGU's in their products. Glass has a very low R-value, and anyone who says they have an R-20 window or door (which would be warmer than your wall) is feeding you a line of... well, let's just say "half truths". The average r-value of a plain clear glass IGU is 1.0. (see http://www.doityourself.com/windows/...entwindows.htm)

The rating to look at on IGU's is u-value. That topic is discussed here at: http://www.doityourself.com/windows/uvalue.htm and http://www.doityourself.com/windows/...malwindows.htm

Regading the offgassing of the argon and krypton (the inert gasses used to fill IGU's) I believe it is true that they do eventually lose their effectiveness. 5 years is likely an exaggeration. I think the government, and especially the NFRC, is trying to figure out exactly how quickly this offgassing occurs so as to establish a minimum standard that all IGU manufacturers must meet. Reportedly, the type of spacer bar used has a lot to do with the durability of inert gas filled IGU's. This sort of opinion favors non-metal spacers such as Superspacer Plus and Swiggle Seal.

Most of the disclaimers I have read refer to off-gassing losses "over a significant period of time", and I have even seen claims that this offgassing occurs at the rate of < 1% per year. But again, studies are still being done on this subject.

I feel very confident recommending argon/krypton options to our customers, since the losses are reported to be so low.

 

Thanks Xsleeper.

I only wish I could get a window or door with a 20 r-value...I was really only talking between 4 and 5.


Anyway, can you recommend a door manufacturer to me that has Argon or Krypton filled units?



Thanks.

 

Foam filled door frames are usually R-5, but it would be suprising if you were able to get an IGU in a full view door that was even R-3. Irregardless, you should be able to get LowE2 and argon as an option on virtually any door. They might not be readily available in stores, but you can certainly order them with whatever options you want.

Well, there is always Pella... Masonite / Stanley make some nice doors, as do Therma-Tru, but there's a plethora of smaller companies that also make doors. Ours come from a small company in Missouri called Target Window & Door. I'm sure you'll be able to find what you want.

A fiberglass door will likely be the most energy efficient. But considering that the glass is where a large percentage of your heat loss will occur, you might look into the benefits of Pella's doors, since some of them come with a 3rd low-e "storm panel" and (optional slimshade miniblinds). The 3rd storm panel will provide the best energy efficiency.

 

Thanks very much.

 

Great reply XSleeper...I am going to add a bit, but your response was on target.

If a consumer is interested in a three-pane IGU, then krypton is the way to go. If a consumer is interested in a dual pane IGU, then argon is the way to go.
Due to the nature of the two gases, krypton is at its peak performance at about 3/16" space between the glass panes. Argon, on the other hand, is at its peak performance at about 7/16" space between the lites.
Argon performance in a narrow IGU spacing is barely better than ordinary air, and while krypton's performance in a wider space (7/16" and up) is still a bit better than argon, it is not nearly enough improvement to make the additional expense worthwhile.

There are several ways to fill an IGU with an inert gas. Most window companies who make their own IGU's simply leave a hole in the spacer and fill from the top down. Almost like filling a glass of water. Argon, being heavier than air, displaces the air and forces it out the top of the IGU (which is being filled in a vertical position) until the argon has replaced the air in the unit. The company calculates the amount of argon it takes to fill the IGU space and fills accordingly, and then seals the opening.

Cardinal IG, which manufactures IGU's for many of the larger window companies, uses a vacuum chamber where the air is evacuated and the argon, krypton (or whatever mixture), replaces the air and the unit is sealed in a gas filled environment. Schuco, a German company now getting into the North American market, also uses a vacuum chamber to fill their IGU's.

SuperSpacer and Schuco's TPS spacer have excellent performance numbers when calculating the amount of gas that can escape from the IGU in the field...both are well within the 1% per year target. The Cardinal XL spacer (stainless steel) appears to have numbers very close to the 1% range as well, but Cardinal almost never reveals their specific numbers. Swiggle and Intercept fall somewhat below the others...Intercept, manufactered by PPG, is supposed to be manufactured with stainless steel also, but many window manufacturers prefer to use a less expensive alloy when using that product. Interestingly, Intercept with Stainless has very good performance numbers, but with one or another of the alloys used for that product, Intercept's performance drops off rather dramatically and the numbers really aren't very good.

Realistically, with the modern spacers, 50 years or more of gas infill life is very possible. Although no one warranties anything like that yet, I have heard that both EdgeTech, manufacturer of SuperSpacer, and Cardinal have been pushing the appropriate code committees to include gas infill life expectancy as part of the IGU "package". Both companies are apparently very comfortable with the ability of their products to maintain seal integrity over the long term.

Once upon a time, 5 to 7 year gas fill life-expectancy was realistic (and still is for some companies), and I think it is quite interesting how many sales folks and other "experts" still use those figures. I suspect that eventually they will catch on that like many other technologies, the performance of windows / IGU's is improving all the time.

 

I am in the process of finalizing a quote from a local window company. The owner actually suggested not paying for argon gas within the window. He said he has not seen enough evidence that the gas does not dissipate away over a short period of time. So I did the quote without the argon gas.

Now I'm wondering if I should include it. The cost is approximately $20 per window and would add about $500 to my total cost. I'm wondering if spending $500 now would save me more than that in heating and cooling costs down the road. Any thoughts? Is the $20 price appropriate? The majority of the windows are double hung, one casement and one bay with two casements. Thanks!