I am pleased to learn that [DWM] is working on an upcoming article on the topic of making versus outsourcing insulating glass units (IGUs). This is an extremely important decision on the part of window manufacturers. After all, what part of a window gets more use than the IGU? It gets direct use by providing a clear view and indirect use by improving the window’s thermal performance.

That’s right—the IGU gets the most daily usage of any part of a window and it is perhaps the most important as well. After all, the number one function of a window is to provide a view. We look out of our windows numerous times a day. And the day that the IGU fogs and our view is obstructed is the day that our window is no longer a window. Yes, window hardware is important, too. We may open and close our windows for fresh air anywhere from never to a few hundred times per year, but we look out our windows thousands of times per year (at least).

So, when we consider the importance of the IGU to the overall satisfaction of the end user, the quality and performance of the IGU is of utmost importance to our customers’ satisfaction as well the reputation and profitability of any window manufacturer.

And when it comes to the quality and performance of our insulating glass units, the four most important factors are the glass, the IG spacer, the IG sealant and the workmanship involved.

An insulating glass unit is comprised by two or more panes of glass separated by the spacer and held together by the sealant or in some cases both the spacer and sealant. The function of glass is to provide a view, impact resistance, a degree of flexibility as internal pressures rise or barometric pressure varies, to reflect radiant thermal energy (using low-E coatings), and to serve as a bonding substrate to the spacer and/or sealant that holds the IGU together. The function of the spacer is to separate two or more panes of glass creating dead air space or spaces that serve as thermal transmission and sound barriers. The spacer is also called upon to contain a desiccating material which captures and detains moisture vapor as it tries to enter the IGU through the sealant. Some spacer systems, such as the flexible spacer systems, also contain an adhesive which bonds the spacer to the glass, thereby relieving the load placed upon the sealant to glass interface—in other words, helping the sealant to do its job.

Every spacer system except those made of aluminum also provides some degree of insulating benefit by retarding the flow of heat through the edge of the IGU. The lesser the degree of metal here the better the insulating value of the IGU and the higher the condensation resistance the IGU possesses. And finally, there is the sealant, which has four major jobs. The sealant must firstly provide superior adhesion to both the spacer and the glass, which holds the IGU together. Secondly, it must also provide flexibility to allow the IGU to expand and contract as daily temperatures fluctuate, barometric pressures vary, or severe wind loads are encountered. Thirdly, the sealant must impede the flow of moisture vapor into the unit, thereby prolonging the life of the desiccant and the IGU itself. Once the desiccant or molecular sieve is totally spent then the unit fogs. And finally, the sealant must hold argon or krypton inside the unit thereby helping to preserve the extra thermal performance that these exotic gasses provide.

There is also workmanship. One can use the best glass, the best spacer and the best sealant, but if the workmanship isn’t there, then Houston we have a problem! The issue here is the availability of quality labor. Manning the IGU production line involves doing a number of critical procedures repetitiously. Employee fatigue sets in and attention to detail can be difficult to maintain. Employee turnover is a real issue with today’s available labor pool. It seems that management is constantly training new recruits. For this reason, high volume production of IGUs begs for automation.

So, these are the factors to consider when it comes to fabricating high quality, high performance IGUs. The upcoming edition of [DWM] will explore the questions that go into deciding whether your company has the core competency to accomplish this internally, or if outsourcing is a better option.

At the end of the day, high quality IGUs with performance levels to match key price points in the market must be made on a consistent basis to help you ensure that your windows do—on a daily basis—what windows are made to do. And that’s provide a view!

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