The Power of Certified & Tested Insulating Glass Units

Now, manufacturers have one standard, one test and one certification protocol to adhere to, rather than trying to decide which of several to follow.
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Gunny Harboe AIA, Director of Preservation Architecture at Austin/AECOM in Chicago, and a past president of the American Institute of Architects, has used insulating glass when visual impacts were minimal and the structure allows. Harboe comments that even on historic work they have used insulating glass to take advantage of energy savings. "If it can improve the insulating qualities of the façade with minimal impact to the historic integrity of the building we will use it," Harboe adds. "Each building and window type presents its own situation but there are always many small details that need to be addressed for it to be done successfully," he says. Harboe and Austin/AECOM architects were responsible for the award-winning restorations of the Reliance Building-Hotel Burnham and The Rookery, two late nineteenth century buildings and recent National Historic Landmark projects in Chicago. In the Reliance Building, Austin/AECOM preservation architects had to replace the all-wood windows and were able to specify insulating glass units while meeting historic guidelines.

For Tom Engstrand AIA, manager of Quality Assurance at Austin/AECOM one important consideration with glass specification is solar heat gain coefficient or SHGC. On projects where glass and aluminum are combined in a curtain wall trying to obtain an overall SHGC for the glazing system, the manufacturer provides aids in determining the overall rating. "Much of the information we obtain comes from the manufacturer," says Engstrand.

Mark Sexton AIA and principal of Krueck & Sexton Architects in Chicago concurs that finding the right supplier is key to properly specified insulating glass. "You have to partner with good manufacturers," Sexton says. "There are a lot of things to look at from both an aesthetic and architectural perspective with regard to insulating glass, including the spacers and other materials. We're able to specifically pick materials with our particular glass supplier."

Krueck & Sexton Architects continues to receive recognition and accolades for its designs, which often involve expanses of glass facades and innovative curtain walls. The company received a 2005 Landmark Award for Preservation Excellence from the Commission on Chicago Landmarks for the Mies van der Rohe S.R. Crow Hall on the Illinois Institute of Technology's College of Architecture campus. Gunny Harboe of Austin/AECOM served as preservation architect on that project as well.

"We continue to push the envelope with material selection and glass," Sexton adds. The reason for certification, generally within any standard, is to provide end users, whether window and door manufacturers, building code officials, architects and specifiers or home buyers, the assurance that they are buying a product that meets or exceeds the applicable code or standard. A certification program can be both simple and complex. In simplistic terms, a product is certified to the applicable standard, such as ASTM E 2190 and a process of initial and ongoing inspection and testing is implemented to ensure it conforms to the standard. The maintenance of the program may be more complex, and involves a formal code cycle and the certification program requirements such as on-going adherence to the quality assurance program, especially if technology changes and the standard requires revision. In addition, some products may need to be recertified as lines change.

History and Relevance

In 1996, a group of leaders in the Insulating Glass industry recognized a need for the North American insulating glass testing and certification processes to harmonize requirements. The Harmonization of Insulating Glass Standards (commonly referred to as HIGS) initiative was formed in early 1997 and the ASTM E 2190 standard was approved in June 2002.

Specifically, the ASTM harmonized standards are:

  • E 2188 Standard Test Method for Insulating Glass Unit Performance,
  • E 2189 Standard Test Method for Testing Resistance to Fogging in Insulating Glass Units, and,
  • E 2190 Standard Specification for Insulating Glass Unit Performance and Evaluation.

This last referenced standard provides the testing protocol for insulating glass units. There are some minor differences in some of the temperatures used and sample sizes required in the ASTM E 2190 Standard. These differences are mostly attributed to conversions from English to metric units. The main differences can best be described by separating the standard into three parts: the high humidity test, the accelerated weathering test and the volatile fog test.

High Humidity Test

In this test, IG samples are subjected to high humidity and temperature. The objective is to force moisture into the hermetically sealed cavity of the IG unit. All three standards use the same type of box and similar high temperatures. The CGSB 12.8 cycles the units from 22°C to 55° C. E 773 and the ASTM E 2190 test method have no cycling. However, both the ASTM E 2190 and E 773 have 50% more time in the high-humidity box. Furthermore, CGSB 12.8 uses separate samples for the high humidity test and the accelerated weathering. The ASTM

E 2190 and E 773 test require the same samples be used in both high humidity and accelerated weathering.

Insulating glass samples are subjected to high humidity and temperature tests.

 

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Originally published in Architectural Record.
Originally published in June 2006

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