Volume 35, Number 10, October 2000

 FenestrationFocus

 

A Global Role Model

a case for the cen proposal and insulating glass

 

by Werner Lichtenberger, P. Eng.

 

The process of harmonizing North American insulating glass (IG) standards has been underway for some time and has been the subject of several trade journal articles. But, what has not been discussed much in North America is the European approach to harmonizing IG manufacturing standards and certification.

The European Committee for Standardization (CEN) proposal prEN 1279 1-6 provides a refreshing view of a quality structure for IG manufacturing. It is time we all learned more about this plan.

European Harmonization Proposal

Recently, the CEN harmonization proposal was presented to the World International Standards Organization (ISO) working group by the Europeans for consideration in the development of a global IG standard. Now, representatives of many countries are familiar with the structure of the CEN proposal.

All IG test methods originated in either Canada or the United States. But, they have evolved in Europe differently, especially in their concepts and approach to IG manufacturing. The Europeans are proposing elements fundamental to IG design, manufacturing and performance that currently are not even considered in North America.

There are three elements of the CEN proposal which North American plans have not fully considered. These include desiccant-depletion measurements, gas-loss rate testing and documented quality-control procedures.

 

Desiccant Depletion

CEN proposes that actual desiccant- depletion be measured after exposure cycling through what is called a “moisture penetration index.” In North America we dew point IG units after exposure cycling. However, this does not tell us how much desiccant was consumed in the process.

Dewpoint measurement tells us little about the IG seal system resistance to vapor transmission, whereas depletion measurement tells us a great deal. The desiccant depletion measurement does serve as a useful relative performance indicator of moisture entering units during weathering. Minimum performance requirements could be based on this measurement.

 

Gas-loss Rate Testing

The European proposal includes gas-loss rate testing after accelerated weathering. This test indicates the continuing unit performance after significant service. (prEN 1279-3 Annex B includes a reference to a ten-year field correlation study supporting the test method.)

Currently in North America, gas testing is required only for the Insulating Glass Manufacturing Association of Canada (IGMAC) certification in Canada. This testing pertains only to initial fill, with data gathering underway on which to base future loss requirements. Additionally, the Insulating Glass Certification Council (IGCC) has a voluntary program in which additional IG units can be tested for initial gas-fill along with regular certification.

Discussion continues at IG industry meetings on the need for official gas testing standards. Meanwhile, National Fenestration Rating Council inspection agencies are trying to determine ways to ensure associated energy benefits are protected.

 

Documented Quality
Control Procedures

Perhaps most importantly, the European proposal includes documented quality-control procedures and monitoring based on production volume, unlike the North American approach. In North America, responsibilities for physical IG test methods and quality-control procedures have been separated. The American Society for Testing Materials and Canadian General Standards Board handle testing while certification agencies assume responsibility for quality-control.

There are also quality-control differences. CEN proposal part 6 requires audits and regular inspection of IG unit construction for conformity with the declared specification. The draft includes a table with a recommended random sample inspection plan where the volume of 12 days’ production determines how many units are to be inspected. The results are recorded for auditing purposes.

North American quality-control requirements are not as rigorous as those in the CEN proposal. For instance, the IGMAC certification program only requires keeping a predefined quality-control record which usually includes batch numbers, adhesion test results, etc. The IGCC certification program only requires that a quality program be in place and that quality-control information be
documented.

The CEN proposal has a holistic document consisting of six separate sections covering all aspects of IG design and manufacturing including quality-control and testing. This form could be adopted by any national certification agency, which would bring truly uniform requirements to the market. What’s more is that there is mutual recognition of certification agencies within the member nations of CEN.

It is my view that this proposal describes a better way forward and the North American IG industry would do well to seriously consider moving in that direction.

 wpe5.jpg (1463 bytes)   Werner Lichtenberger, P. Eng., serves as special projects manager for TruSeal Technologies based in Beachwood, Ohio.

Fenestration Focus appears monthly with rotating columnists.

USG

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