GPAD Concludes with Thermal Optimization Discussion
June 26, 2012

FeneTech's Glass Processing Automation Days concluded this afternoon with a number of thought-provoking discussions, including one on the thermal optimization of insulating glass (IG) units, led by Mike McHugh, president of Integrated Automation Systems.

According to McHugh's presentation, the IG business has gone through continuous transformation in the last 30 years. While each change was often labeled "incremental" and not worth the investment, the accumulation of these options has resulted in a much higher performance IG unit than has been produced in the past, he pointed out.

McHugh said these changes have presented a new challenge: How do we best combine all these improvements to produce the highest performing IG unit that is both durable and cost effective? He said there are a number of options to consider.

These include:

  • Hard coat or soft coat;
  • Single, double or triple silver coating;
  • Fourth-surface coatings in two pane units;
  • Sixth-surface coatings in three pane units;
  • Double pane vs. triple pane;
  • Symmetric vs. asymmetric;
  • Edge effect of the spacer;
  • Argon, krypton or air;
  • The mix of argon, krypton and air; and
  • Overall IG unit thickness.

McHugh explained that the purpose of his analysis was not only to provide specific answers to the cost/value question, but also to demonstrate a methodology to evaluate the cost of different IG process options and compare it with the resulting U-value for a generic vinyl window.

"Using this methodology provides a better understanding of both the cost and ability to affect performance," he said in the presentation. "I am excited to be conducting an analysis that does not discuss center of glass or even the U-value of an entire unit, but only its contribution as a component of a window."

McHugh broke the market into three segments based on window glazing pockets:

  • ¾-inch units;
  • 7/8-inch units; and
  • 1-inch units.

The base unit is a ¾-inch double unit with:

  • 2.5-mm clear panes;
  • Stainless steel spacer;
  • 0.563 air space;
  • Air-filled; and
  • 2.5-mm double stack low-E.

McHugh said the ¾-inch unit was used as the base; he then accounted for the cost to upgrade from this base to the different unit designs considered. The same incremental costs were used consistently for all designs.

"Keep in mind that if you regard the process as a credible way to make evaluations, it would be relatively easy to substitute your particular numbers for cost considerations," he said.

In his conclusions, McHugh said R-5 windows are cost effective. He pointed out that:

  • Whatever glazing pocket size you make, thermal optimization will play a significant role in your product development;
  • There are lots of options using the above combinations, and no wrong answers;
  • If there is a wrong answer, it is that producing an R-5 window is not cost effective. "With a manufacturing cost premium in the range of $2 per square foot of glazing, I believe we as an industry can provide solutions to the rising cost of energy, as well as CO2 reductions," he said;
  • "It is clear Energy Star has leveled the playing field. Companies that win in this new competition will be incorporating thermal optimization as tool for developing future products;" and
  • He also said, "The incremental changes have not stopped happening. We as an industry are continuing to develop better performing products for our customers and the outlook is positive."

This story is an original story by USGlass magazine/USGNN™. Subscribe to USGlass magazine.
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