Q&A: Is it a worth the extra cost to buy windows filled with argon gas?

The replacement windows I'm considering buying come with the option of using argon gas to boost their energy efficiency. Should I spend more to get the argon gas?

It is generally not a good investment to replace windows just for energy-efficiency purposes. But if you need to replace irreparable windows or are undertaking a home remodel, then consider the incremental costs of higher-efficiency replacement windows over models without such features as specialty gas fills, including argon, or low-e coatings.

Large incremental costs for these options generally outweigh their benefit. Argon, for instance, typically increases the insulating R-value of a window by only half a point. (Insulated-glass windows, also called double-pane glass, typically have an R-value of around 2.0 to 3.0. R-value is the measurement of thermal resistance; the higher the number, the more efficient the window. Learn more about the energy performance of windows.)

This small increase in insulating value from the argon gas will get you slight energy savings, but the additional initial cost could significantly extend the payback time for the windows. What's more, the argon does little or nothing to reduce transmission of ultraviolet and infrared radiation. UV light from the sun can damage your furnishings but, more important, infrared radiation transfers heat into or out of a home. Studies have shown that windows with a low-e coating can measurably reduce solar heat gain during cooling season (assuming you do not draw curtains or blinds anyway). However, homes in cold climates tend not to see a benefit from this option.

It's worth noting that many manufacturers of high-quality windows, including all those we tested for our latest report on windows, now use argon-filled glass as the standard for their windows. In fact, some companies might charge you more if you want windows with glass that provides less insulation, including models with only air-filled glass or with no low-e coating.

Essential information: Learn how to choose the best windows, understand the different window types and designs, and find an expert installer.

Comments

[john ericson]

i need advise for finding a homw warranty co., one that is better than american home shield. thanx j ericsin

[Phil lewin]

I could not disagree more with the conclusion of this article that argon gas is not worth getting when upgrading windows. First, if you look at argon in a clear unit (which is another error) you will get a poor value, so only look at argon as an upgrade to a SU with Low E. Anyone buying an SU without Low E must be living somewhere where neither heating nor cooling is a cost factor!

Using a program called Frame, I can simulate a R3 center glass value for a sealed unit with a hardcoat Low E. (Values for softcoat would be slightly different, but the incremental would be so close as to not be an issue.) Add argon and the R goes to R3.5.

This is where I wish a real engineer would step in and take over the math, but I will crudely proceed. In Canada we have a system called an "Energy Rating". I have been told that 1 point R is roughly the equivalent to 6 point ER, so the half point differential is a differential ER of 3 points.

In the mid 80s, one of our utility companies did the math and announced that each point ER was worth 5.5 cents per year per square foot in an electrically heated house. Well, all costs for fuel have risen in the last 20 plus years, but even sticking to this, let's do the math!

So, 3 points ER would save a grand total of 16.5 cents per year per sq. ft. Now, what does argon cost per sq. ft.?

Let's say that a consumer pays $1.50 per sq. ft. more for this option. This is on the high side of costs. At 16.5 cents savings per year, it will take 9 years (crude accounting, I know) to "break even". Since a properly made sealed unit will last much longer, after 9 years, the homeowner is saving money.

If the savings is higher than 5.5 cents (and I'm sure it is) and the cost is lower than $1.50, the payback will be much faster. The break even point for adding argon to a Low E unit can be as fast as 3 years, depending on whose costing one believes. The above math was an ultra conservative analysis. Whoever wrote the above article gave no detailed analysis. This was a very scientifically poor article with misinformed conclusions.

Phil Lewin
V.P. Marketing - Vinyl Window Designs Ltd.

[TRACY]

regarding the american home shield. what a rip off that starts with the real estate company and mortgage company that tells you they both have this policy and have used it several times with no problems to the contractors that come out get your 60.00 fee and report incorrect information about your service call. i'm in the process of small claims court with this company. they need to go down.

[Bill Morrell]

I have to point out some information on your article dated 8/20/08 about argon filled windows. While argon may not increas the "R" value of the glass in the window by a .1, it does however dramaticly increase the "U" value. Here in New England,and other cold climates, it is the presence of Argon or Krypton gas in between the glass that slows down the heat loss from inside you home. Another mistake in that article is the mention of double glass filled with "air". This is incorrect. Double Glass becomes "Thermal" when, through the assemble process and at the last moment befor final seal of the two glass, the "Oxegen" is REMOVED from in between the double glass. Air transmits cold. By removing the air and sealing the glass, you now have a thermal glass unit. One without air in between, therefor slowing down the process of temperature transmission through the glass. At the same instant of the final seal, Argon/Krypton organic gas can be injected between the glass. This will cause the transfer of heat/cold to slow down even more. Here in the north east, gas filled is only available in conjunction with Low E glass/Double low E glass. I cant speak for other parts of the country. The enregystar web site can confirm that U-value is very important in the north and U-value rated windows are the best to buy and are called "Energystar" rated. Here in Connecticut an "energystar" window is sales tax exempt, and a .30 U-value window now has a federal tax incentive of 30% for 2009 and 2010.