October 2005

Volume 6 Issue 9 October 2005

Ways & Means
Attendees Stay on Top of IG Happenings During IGMA's Summer Meeting
by Ellen Giard

The Insulating Glass Manufacturers Alliance (IGMA) held its summer meeting August 6-9 at the Westin Halifax Nova Scotian in Halifax, Nova Scotia. For four days manufacturers, suppliers and others involved with insulating glass (IG) production took part in working group sessions and technical presentations all geared toward finding ways, means and methods for improving production practices.

Working Group Meetings
Bill Lingnell, IGMA technical consultant, chaired the visual quality working group in the absence of co-chairs Roland Temple of Velux and Joel Dobson of Pella. The group is working to develop guidelines for what is permissible in the airspace of an insulating glass unit (IGU). The group is targeting things that happen during the manufacturing process-what’s under the manufacturer’s control-such as fingerprints and dirt.

Lingnell stressed that at this point the document is being written as a guideline, not a standard, but that it is being written in ASTM format.

“We’re trying to help identify unintended visual obstruction,” said Lingnell. He added though, that the list will not be all-encompassing, as they may find obstructions that they’ve never before encountered.

The first meeting of the thermal stress working group, chaired by Steve Crandell of PPG, also took place. The group is working on trying to differentiate stress breaks and what triggers the glass to stress/fracture.

“We don’t want to duplicate the efforts of other documents [i.e. IGMA’s “Preventing IG Failures” document],” said Crandell. “We need to help others understand [thermal stress] and define thermal stress conditions.”

One thing the group discussed was creating a “dos and don’ts” design guideline that would assist those who are designing and specifying insulating glass.

Chris Barry of Pilkington suggested conducting a survey to see what [products, installations, etc.] are breaking in the field. The survey would help determine which products are more at risk.

“We could put together an incredible database of information through this survey,” said Barry.

Bruce Virnelson of PRC-DeSoto chaired the gas permeability working group meeting. The group’s efforts are focused on measuring the rate at which argon permeates through an IGU. During the meeting members looked at data from a survey conducted by TNO of the Netherlands. TNO has recommended that the group review data points and then have samples X-rayed. Andre Piers with TNO gave a talk on phase one of the project during the technical presentation.

The newly-created education committee also met. The group discussed ways in which they could provide more education and information to members.

“We want to always drive education as part of our meetings,” said Mike Burk of GED who chaired the meeting. Some of the measures the group discussed included creating an educational seminar on IG manufacturing quality procedures and also developing an AIA course that would be on certification and ASTM E 2190. Margaret Webb, IGMA executive director, said that IGMA exhibited at the AIA show this year and had an excellent response. In light of that, she said that IGMA is now looking at other ways to provide more information to architects and builders.

Technical Matters
During the technical services committee meeting Webb gave an update on the Canadian standards development and harmonization.

“Everything was on track to have the ASTM reference added to the Canadian building code, but the Provincial Territorial Policy Advisory Committee on Codes said they were not going to reference it because they did not have a method in place to make the [interim] change,” said Webb. “We’re going with the next code cycle, but they do not know when that will be.

“This has not stopped us from having a harmonized standard,” added Webb, “but it would have been nice to have it in the building code.” She explained that they are now going to individual jurisdictions for adoption.

Webb also updated the group on IGMA’s involvement with the National Fenestration Rating Council’s (NFRC) non-residential certification and ratings program.

“We’ve spent a lot of time on the new proposed procedure,” she said, explaining that IGMA has now been involved in the program for a year.

“Where we are today is substantially different than where we were a year ago,” she said.

Learning Sessions
Technical presentations were a part of the summer meeting as well.

As the NFRC’s efforts to create a non-residential certification and rating program was a hot industry topic, Charlie C´urcvija of Carli Inc. gave a presentation on a component-based model approach to simulation of non-residential fenestration products. He described the component modeling approach (CMA) as a simple methodology to simulate thermal and solar-optical performance of fenestration products. Simulations are performed for three separate components: the framing system, glazing system and spacer system. Indices are calculated for U-factor, solar heat gain co-efficiency and visible transmittance. Future developments, he said, will focus on condensation resistance.

Henry Taylor of Architectural Testing Inc. (ATI) followed with a discussion on alternative methods for measuring argon gas fill non-destructively. He explained that ATI has designed and built a device called a heat flow meter, which measures thermal transmittance between two lites of glass.

“The heat flow meter was intended to do research work for commercial products, but we found it did a tremendous job of checking gas [argon] fill,” said Taylor. “It is a valuable source for test data.”

The heat flow meter can be used horizontally, vertically or at an angle to measure convection. Taylor explained that the heat flow meters can detect and measure 1/10 of 1 percent change in thermal transmittance.

Durability Issues
Another session of technical presentations focused on adhesion and sealants, as well as insulating glass durability.

The session began with a panel discussion about adhesion. Panelists were Chris Barry of Pilkington North America, Lori Postak of TruSeal technologies, Bruce Virnelson with PRC-DeSoto and Lena Chernyak of H.B. Fuller.

Barry began the discussion, and talked about some of the necessary measures IG manufacturers should take in order to ensure adhesion. He advised having suitable solvents to dissolve dirt on the glass, hot water to speed dissolution, rotating brushes that push the water away from the rinse and clean rinse water. He also cautioned manufacturers to not seal an IG that is still hot from washing, as it will create a dished unit.

Virnelson next talked about adhesion theories and test methods, and encouraged manufacturers to choose test methods that are best for their specific applications, as there may be several that are suitable.

Postak spoke about quality inspections and confirming IG sealant durability. She advised managers to instill good manufacturing practices, provide troubleshooting guidelines, to define the final inspection role, to follow up on failures in the field, demand supplier certification of properties and to perform regular on line inspections.

Chernyak continued the discussion on adhesion, further looking at theories, testing and other practices manufacturers should follow in order to ensure a successful sealant.

Bob Spindler of Cardinal IG gave a presentation on the effect of glazing sealant thickness on glass breakage. He talked about characteristics of glass breakage, glass fracture analysis, including thermal stress, bending stress and impact, and stress analysis with glazing sealants.

He stressed the importance that IG manufacturers and window manufacturers follow the recommendations for use provided by their suppliers. He explained that if products, such as a silicone glazing, are used incorrectly it could lead to a failure. His recommendations to reduce failure included:
• Using 2.3 mm heat-strengthened glass or thicker on lites experiencing breakage;
• Providing clearance between glass and sash to reduce opportunity for contact;
• Following IGMA glazing guidelines for sealed glass units;
• Making sure the edges of glass are not damaged during glazing;
• Providing a minimum sealant dimension of 0.030 inches between sash and glass; and
• Conducting stress analysis to determine the magnitude of stress during glazing.

An update on the IG durability steering committee from Gerard Lagos of Andersen Windows was the meeting’s final presentation. The committee is not actually part of IGMA, but is coordinated by Aspen Research Corp. and funded by the Department of Energy (DOE). The group’s efforts are centered on researching and advising on IG durability, so it has close ties to IGMA.

“There is a large inventory of IG and we need to increase consumer confidence,” Lagos said. “As more IG is out there [in the field] we need to keep the number of failures down.”

The committee has recently recommended to the DOE that IG durability be made part of the Energy Star® requirements.

“We’re continuing to improve the current state of IG durability and preparing for new technology introductions,” added Lagos.

The Next Meeting
IGMA’s 2006 annual meeting is scheduled to take place February 22-26 in LaQuinta, Calif.

Ellen Giard is a contributing editor to DWM magazine.