The Key to Performance Longevity
by Richard Rinka
The performance of the sealed insulating glass (IG) system
is critical to the overall long-term thermal performance of a complete
fenestration system. While technological advances have improved overall
fenestration performance, they have also introduced variables that may
impact the unit’s performance. As examples, loss of insulating gas or
the deterioration of low-E coatings due to moisture intrusion can degrade
On July 1, 2010, the National Fenestration Rating Council
(NFRC) began enforcing a requirement for third-party IG performance certification.
As NFRC ratings are now required, the Energy Star® windows program also
requires IG certification by reference. AAMA and Associated Laboratories
Inc. jointly serve as one of four third-party certification bodies authorized
to grant IG certification.
The typical process is for the IG manufacturer to assemble 12 identical
IG test units, 14- by 20-inches in size, each with the same spacer and
sealant combination for which certification is desired. This is done in
the presence of a certification agency inspector, who permanently identifies
each specimen and seals each with a tamperproof seal. The sealed samples
and supporting data are forwarded to an approved independent test laboratory
of the manufacturer’s choice for testing.
ASTM International publishes the recognized test methods
and specifications for IG performance:
• ASTM E2190, Standard Specification for Insulating Glass Unit Performance
and Evaluation, which provides the applicable test and assessment methods
as the basis for evaluating the durability of IG units. The qualification
of test specimens is based on frost/dew point and on the absence of fog
after the specified test durations according the ASTM E2188.
• ASTM E2188, Standard Test Method for Insulating Glass Unit Performance,
prescribes the durability testing sequence that encompasses periodic frost
point testing per E546/E576 and spark testing of gas filled units per
• ASTM E546, Standard Test Method for Frost/Dew Point of Sealed Insulating
Glass Units, is used to determine the frost/dew point within the air space[s].
(Alternatively, ASTM E576, Standard Test Method for Frost/Dew Point of
Sealed Insulating Glass Units in the Vertical Position, may be used.)
• ASTM E2649, Standard Test Method for Determining Argon Concentration
in Sealed Insulating Glass Units Using Spark Emission Spectroscopy, provides
a means for determining the concentration of argon in sealed insulating
glass units under controlled conditions in compliance with the apparatus
• ASTM E2189, Standard Test Method for Testing Resistance to Fogging in
Insulating Glass Units, is used to show that the components in an IG unit
will not out-gas a volatile vapor that could condense on the interior
glass surfaces. Upon receipt of a Notice of Certification Authorization
(NCA), the licensee may begin applying the AAMA/ALI IG certification mark
to each unit of that product family and list the product in the AAMA/ALI
certified products directory. Test reports are valid for 24 months from
the date that the NCA is issued and then must be retested and validated
in the same manner as for initial certification.
Without prior notice, an ALI inspector visits the licensee’s manufacturing
plant(s) twice annually to verify the continued use of materials and methods
used to produce the originally approved samples. In addition, the inspector
verifies the ongoing effectiveness of the manufacturer’s Quality Management
At a minimum, QMS requirements for IG manufacturers, as
set forth in NFRC 706, Requirements for Participating Insulating Glass
Note that while independent certification of IGs is not
a prerequisite for certification of a completed fenestration unit to NAFS,
NAFS compliance does require a test report showing compliance of the IG
with ASTM E2190 or CAN/CGSB 12.8.
Richard Rinka serves as certification manager for
the American Architectural Manufacturers Association in Schaumburg, Ill.
© Copyright 2012 Key Communications Inc. All rights reserved.
No reproduction of any type without expressed written permission.