Recently a customer of mine asked me if I knew how much it cost to add gas to his windows. He wanted to make sure that he was charging enough. It occurred to me how many customers who offer gas filling do not even know how much it adds to the cost of their windows or what they should be charging customers for the gas.

In fact, I have been asked this question so many times that I went ahead and constructed a simple Gas Filling Cost Calculator for my customers to determine what it is costing them to add gas to a window of given dimensions and airspace size.

One just needs to know what they are paying for the gas in dollar-per-liter, whether it be argon, krypton, or a blend, as well as the size of the insulating unit (IGU) and airgap, the number of cavities and number of IGUs per window. Also, enter what the waste factor might be. If you feel you are wasting 20%, then the waste factor is 1.20. Twenty percent is a safe assumption for argon. Due to the fact that the costs for krypton are so much higher, many suppliers offer a recovery unit that collects any krypton that might otherwise be wasted and deposits it into a recovery tank, which is then sent back to the gas supplier.

Once it is evaluated for content, then a corresponding credit is issued. Now this calculator will then tell you what it is costing you to put the gas into the window assuming no added labor costs. This particular example shows that for a double-hung window with two 24 by 36 inch IGUs featuring half-inch air-gaps in dual pane units, it will cost the manufacturer approximately 51 cents in argon to fill the unit assuming 20% wastage. A second example using the Gas Filling Cost Calculator Loaded with Krypton Data shows that a typical triple pane double hung window of the same size, but filling ¼-inch cavities, would cost about $8.92 per window. Quite a difference!

Now the “no added labor cost” is a valid assumption if you have a fully automated IG line like the ones sold by Lisec, Forel and Erdman. These machines automatically flood a chamber with gas as the lites of glass are being pressed and then automatically and consistently seals by a robot. There is no extra labor involved. Also, this method features a huge advantage from a quality and consistency standpoint in that the IGU isn’t compromised by adding any gas filling or vent holes, which can become possible leakage sites down the road if not sealed perfectly.

However, if you are running a manual or semi-automated IG line, then you are into some additional costs associated with labor. In these scenarios, IGUs are typically made with one or sometimes two entry (or vent) holes into which gas filling/venting wands are placed and the gas is introduced simultaneously as the air is sucked out. Modern gas filling machines feature automatic shut off after an oxygen sensor determines that a predetermined argon or krypton content has been reached. Most manufacturers shoot for a minimum in the 90% to 95% range.

After this is done, the IGU itself must be sealed with the chosen IG sealant, or, if this has already been done, then the gas filling wand entry/exit holes (or gaps) must be “patched” with the same sealant used to seal the unit itself. This is all done in a batching operation as units are placed on harp racks, rolled over to the gas filling station, filled, sealed and then hopefully inspected for proper sealing or patching. If the patching or IG sealing operation is done in a hurried fashion, then workmanship may be compromised. Your energy-saving gas is then sure to escape the unit somewhere down the road, which defeats the whole purpose.

So, unless you are running a totally automated IG line, all of the labor costs associated with these various tasks surrounding the gas filling and re-sealing operations must be taken into account and a labor cost-per-unit must be then assigned and added to the material cost previously calculated with the Gas Filling Cost Calculator to get to the bottom line when it comes to these manual gas filling operations.

The bottom line is that it is important to understand just how much extra cost is associated with introducing argon or krypton gas into the IGU and charge accordingly to protect your margins. Adding gas to the IGU results in some significant benefits to the overall thermal performance, especially in the case of krypton in smaller air gaps. But if you do not know your costs you could be giving it away. So, analyze your costs associated with gas filling and be sure to train your sales staff to sell the added benefits. The end goal should be happier customers with improved profitability for the door and window manufacturer.

1 Comment

  1. Jim, this is a nice article! Spot on with the process and cost variations when comparing automation and manual processes along with the difference between Krypton & Argon. I will post this article on our inter company news. Well Done!

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