Volume 49, Issue 3 - March 2014

The Case for GANA

BEC Input Needed in All Divisions
by Chuck Knickerbocker

Having attended Building Envelope Contractors Division (BEC) of Glass Association of North America (GANA) meetings in Vegas for most of the last nine years, it’s only recently that I’ve learned that there’s a lot more to GANA than BEC. Does BEC know what’s going on in the other GANA divisions? The answer is probably not, if your experience has been like mine. Considering the ground that was covered during the last GANA annual meeting February 4 - 6, 2014, can a case be made to re-think that situation if you’re a glazing subcontractor? Here’s a look at some of what was covered.

Changing Realities
Much of the focus of the recent “battle for the wall” victory came out of the GANA Energy Division, with Tom Culp of Birch Point Consulting leading the presentations at the ASHRAE meetings. With help of the glass manufacturers who are part of the GANA Flat Glass Division, the proposed amendments were voted down at the ASHRAE board level by a 20 – 1 margin. That effort had a lot of contributions made by many people inside and outside the glazing industry, but the technical effort had a lot of push from GANA.

"The stimulating ideas from a design and execution standpoint were staggering, all of which BEC subcontractors can use when they call on their architect customers to assist with design issues."

Even with all the good of this victory, our industry still must adapt to changing realities. For example, life cycle analysis (LCA) is getting closer to becoming something we have to deal with, just as we now have to address structural performance and air and water resistance. The GANA Energy Committee is attempting to set the standards for the product category rules by which individual products will be measured against each other, leveling the table so that concise and accurate comparisons can be made. Some manufacturers are doing a lot with this now for their products. LCA will trickle to the glazing subs, as part of it includes how much energy a product takes to perform over its expected service life, and how much energy it takes to recycle it at the end of that time. Glazing subcontractors will have to be conversant in this language to be able to explain it to their customers.

A leading national architecture firm has already developed in-house standards for determining which products to use on its projects. For instance, in comparing a precast concrete and punched opening window to full glass and aluminum curtainwall, the total glass curtainwall came out a poor second. It takes considerably more energy to produce aluminum—from the quarry to the extrusion press—than it does to make concrete. The basis for the firm’s decision came down to the cost per square foot of the energy required to get the opening on the building. “Battle for the Wall II” might be forming in this arena.

Educational Perspectives

As designs and products get more sophisticated, architects can design with glass and still meet energy goals. This was shown at the GANA annual meeting, in which presentations from universities focused on how to address and improve thermal performance of curtainwalls, especially glass. Another presenter talked about how the location of punched windows in relation to their surround can affect their thermal performance by as much as 10 – 15 percent. He noted that moving a window back from the outside surface even as much as 2 inches can reduce the energy footprint of the building.

Another example of improvements in glazing efficiency discussed that European designs are now incorporating operable panels in glass mullion system installations to aid in ventilating lobby spaces. Options included:

• Operable screens, such as venetian blinds but with monolithic panels that slide over windows outside, rather inside the building;
• Systems that change the orientation of the glass to the sun, creating a visually stimulating saw tooth design for the plan of the curtainwall. In this configuration, the staggered panel reduced the sun’s incident angle on the glass, while the height of the stagger also created a shading screen for the light next to it; and
• 3D spandrel panels with super insulation that act as shading devices.

The stimulating ideas from a design and execution standpoint were staggering, all of which BEC subcontractors can use when they call on their architect customers to assist with design issues.

Another high point was Jim Benney’s presentation about trying to modify the NFRC’s computer modeling approach (CMA) for certifying exterior, vision glass curtainwalls to accept spandrel, pattern frit, or translucent interlayers. He showed how complicated it can be to determine actual performance of these types of glazing within the confines of the NFRC certification process.

The conference also had several laminated glass topics that will eventually reach the BEC glazing subcontractors. One, in the Laminating Division, centered on the use of laminated glass in doors, and if and how the interlayer compresses when hardware (pivots, push pulls, etc.) are attached, and if there’s any visual distortion when it is compressed. Another topic in that division dealt with how glass strength changes when laminating different thicknesses. The group also covered weathering testing of laminated glass; presently, there is no standard for weathering. For example, standards do not exist for all the glass in canopies or similar installations with exposed edges, regarding the duration or attributes laminated glass should have after prolonged exposure, such as delamination or separation at edges, etc.

All of these points might eventually affect how glass handrails are designed, fabricated and installed. Given the number of glass handrail failures over the last couple of years, the Canadian code authorities currently are developing a standard that will be balloted this year. That code may require wind tunnel and impact-resistant testing, monitoring frequency after installation and what to look for when inspecting, as wells as certification for handrail installers.

When asked what they wanted most for the exterior envelope, the Energy Day participants’ main wish was for performance-based, rather than prescriptive codes. GANA, across the board, is trying to help lead the industry there throughout all the divisions.

The Insulating Glass division is going to look at whether insulating glass requires framing members to support all edges, or if butt-jointed glazing will be permissible. There have been numerous requests from the architectural community to design insulating glass without frames on two edges, doing away with either verticals or horizontals. If the horizontals are deleted, the discussion then becomes how to support the dead load, and more specifically, can the glass be supported on setting blocks located at or immediately adjacent to corners. These two issues are going to be reviewed in conjunction with the Insulating Glass Manufacturers Alliance.

Full Circle
Most of what’s covered in GANA divisions other than BEC eventually makes its way there in the form of projects bid, sold, and installed. As a result, BEC members have a vested interest in being involved in GANA’s other divisions. Currently, these other divisions operate without any direct input from those within BEC. Granted, the manufacturers who predominate the membership in these other committees might indirectly take back to the GANA division level concerns which their customers voice (BEC members or not). But, that’s not a given, and their take is going to be from their own perspective, not necessarily the same as that of the BEC member. GANA glazing and sealant manuals are referenced all the time in specifications, but so are some of the other resources GANA is producing, including the many Glazing Information Bulletins.

Chuck Knickerbocker is the curtainwall manager for Technical Glass Products (TGP). He is the chair of the Glass Association of North America Building Envelope Contractors Division Technical Committee.


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