Fenestration Focus March/April 2021August 18th, 2021 by Nathan Hobbs
Gaining Traction: Thin Triples Meet Stringent Codes, but Come with Special Considerations
By Larry Johnson
Building professionals in California have now lived with the state’s Title 24 updates for residential buildings for more than a year. As of January 2020, all new residential structures have been required to achieve Net Zero Energy (NZE) consumption. High levels of window performance are part of the standard, mandating a maximum U-factor of 0.30 and a maximum solar heat gain coefficient of 0.23.
Meeting those goals effectively and economically remains a challenge and has required some innovative thinking on behalf of window makers. One technology that has shown promise and has gained increasing traction over the past year is the “skinny” or “thin” glass triple. It’s my expectation that we’ll hear more and more industry chatter about this in the coming months and years—beyond just the borders of the Golden State.
A quick primer: Compared with a traditional triple-pane insulating glass unit (IGU), a thin triple IGU utilizes an ultra thin center lite that is typically between 0.7 mm and 1.3 mm thick. Filled with krypton, these units can deliver outstanding thermal performance.
As it stands today, skinny triples are an increasingly viable technology that residential window manufacturers can leverage to enhance performance, but of course, some special considerations still must be made.
One of the major advantages of thin triple IGUs over their conventional triple-paned counterparts is that they don’t require a change in window framing— they’re effectively a direct swap for double-paned glass. If you’re considering adopting the technology, whether as a means for meeting code in California or to simply differentiate, this means you don’t have to completely redesign your entire window system. What’s more, thin triples are nearly the same weight as double-paned IGUs. Traditional triples have come with concerns around increased sash weight, especially on casements, requiring significant reinforcement. Thin triples’ ability to eliminate those concerns while offering better performance is significant.
As such, thin triples can be more easily incorporated into an existing system. This can be a big advantage for window manufacturers who want to quickly pivot to offering a higher-performing window applicable for a wide range of buildings. They’re also a good option for both new construction and retrofit applications—they can replace a double-paned IG unit or sash without replacing the installed frame.
Of course, these advantages do come with a few special considerations that must be made during the manufacturing process. For example: The first time I personally handled an ultrathin center lite used in thin triples, I accidentally broke it. Given how delicate the pane was, this was not particularly hard to do. As such, careful handling by plant crews is essential during the assembly process of thin triple units. Consider also that any blemish to the center lite potentially can lead to a warranty claim (which is also true of traditional triples). A homeowner who spots, say, an uncleanable fingerprint in the middle of their window is going to want some answers.
As with many challenges associated with modern fenestration manufacturing, these concerns can be alleviated by automated processes which remove manual touchpoints from the fabrication process. This is yet another reason to consider investing in cutting-edge equipment if you haven’t already.
But better solutions are possible—some of which can make for significant cost and production advantages for door and window companies that want to seize the opportunity presented by skinny triples.
I’m expecting to see increased adoption of this burgeoning technology over the next few years—in California, and in any application where the highest levels of thermal performance are desired. It’s certainly something worth keeping an eye on this year and beyond.
Larry Johnson is vice president of sales, North American fenestration, for Quanex Building Products.
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