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USGNN Original StoryTechnical Presentations Take Place During IGMA Meeting

During the Insulating Glass Manufacturers Alliance's (IGMA) annual meeting, which took place this week at the Hyatt Mission Bay in San Diego, attendees were treated to a number of technical presentations.

Yesterday morning IGMA technical consultant Bill Lingnell of Lingnell Consulting Services presented an update on his thermal stress research pertaining to insulating glass (IG). "We need to understand why you don't just jump from monolithic to IG," Lingnell opened.

David Bailey of Bodycote Testing Group (left) and Bruce Virnelson of PRC DeSoto International presented the topic: "ASTM E 2190: Has the Bar Been Raised?"

According to his presentation, "There is a pre-stress in the IG unit due solely to the temperature difference from outside to inside without the influence of solar intensity." Lingnell then added, "Even before you start putting sun on this, there are some conditions that are happening."

After walking his listeners through the basics of thermal stress considerations for monolithic glass-ranging from frame type and size to interior and exterior building conditions-Lingnell proceeded to walk through his analyses for addressing the differences that IG gap has on thermal stress reactions.

While his research provides for "a numerical procedure … that shows the magnitude of thermal stress in IG," Lingnell pointed out that this is simply the beginning of his research in this area.

"We have some good examples here but that won't take us as far as we want to go," he said. His goal is to continue his research with a second phase that will entail creating "dozens of thermal stress charts" to lead to a procedure for predicting thermal stress in IG, and perhaps, down the road, a third phase to address the curves thrown into the mix by the newer triple-glazed units.

IGMA technical consultant Bill Lingnell presented an update on his thermal stress research on insulating glass.

For Phase II, Lingnell said, "We've got the process, we know it works, but we have to create these runs."

"We know how to design for wind load but we don't know how to design for internal stress," commented Bob Spindler of Cardinal from the audience. "I'm very excited about Bill and Lynn [Beason's] research. It's the first time someone put together a program on thermal stress and what the recommendations should be."

Next to take the floor yesterday was David Bailey of Bodycote Testing Group and Bruce Virnelson of PRC DeSoto International. The pair addressed ASTM E 2190, asking, "Has the Bar Been Raised?"

In providing some background on the various IG test methods in use (ASTM E 773/E 774, CAN/CGSB 12.8 and the new ASTM E2190 endorsed by IGMA and the Insulating Glass Certification Council), Bailey happened to address a topic that had been much in discussion during working group meetings earlier in the week: the volatile fog test. While Bailey provided information on how his laboratory follows the test methods, he did comment in regard to E2190, "I think it would be to the industry's benefit and the laboratory's benefit to have the light source and the distance and the angle to be very specifically defined."

Jim Larsen of Cardinal IG presented "Next Generations of the Energy Star Program: How Will It Affect You."

Virnelson went further into comparing some of the differences in between the tests, before providing several charts on failure rates for each test method.

"As you make a sample long enough, you get better at making it," he commented in explaining trends. He summarized that while it should be more difficult to get units through the newer method's way of testing for volatile fog and weathering, "the data seems to suggest … might be a little bit more difficult in the fog … not a lot more difficult in the durability." However, he added, "It is too early to tell."

Next up, Jim Larsen of Cardinal IG presented a talk on the next generations of the Energy Star program (CLICK HERE for related story). Larsen explained of the reasoning for the revisions that the Department of Energy is "thinking Energy Star doesn't differentiate itself enough from the codes." However, he expressed concern that once Energy Star raises it's bar, so to speak, the model codes would follow.

"Is this really going to improve energy efficiency?" he asked as he walked his audience through the revised climate zone maps and compliance examples showing that in some areas there aren't products available to meet the requirements.

CLICK HERE to read more about IGMA's 2009 annual meeting.

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