Triple-glazed, curved glass curtain wall system features Technoform
Steve LeBlanc, Contract Glaziers West Inc.
Bringing the vision to reality, construction manager EllisDon worked closely with Contract Glaziers West Inc. to engineer the custom, high-performance, unitized, structurally glazed, aluminum-framed curtain wall system, and to manufacture and install it to precise specifications.
The curtain wall relies on Tianjin North Glass’ (TNG’s) state-of-the-art, bent, triple-pane insulated glazing units (IGUs) with two low-e coatings from G-Crystal Glass Group. Technoform’s bendable, yet durable, warm edge spacer separates the three panes of glass, creating an insulating barrier at the perimeter of the IGU to improve thermal performance. This combination of high-performance components allows the IGUs to meet the project’s high thermal performance requirements and achieve the overall energy-saving, sustainability goals.
Clarity Architectural Products introduced TNG to the 707 Fifth project team as its preferred supplier for the building envelope, capable of fabricating the sophisticated, bent, multi-pane, insulating glass in custom shapes, large sizes and at the high level of quality specified. In total, TNG suppled 220,000 square feet (20,400m2) of glass to Contract Glaziers West, which fabricated the curtain wall in its Windsor, Ontario, facility then transported the system to Calgary for installation on the project.
“TNG was one of the few glass manufacturers willing to accept the challenge of producing IGUs with custom low-e coatings, such that they looked the same whether in the concave or convex orientation,” explained Technoform’s Helen Sanders, PhD. Technoform’s TGI Spacer-M serves as the standard for TNG and its large, premium insulating glass products.
“Using Technoform's spacer for this application came from a recommendation by the Tianjin North Glass team,” said Contract Glaziers West’s Steve LeBlanc. “We affirmed their preferred spacer solution via our thermal modelling for the project, thus establishing that it would provide the performance values we required.”
The thermal performance requirements of 707 Fifth included stringent whole unit U-factors of 0.91 W/m2K (0.16 hr/ft2F), according to Dirk Schulte, formerly with TNG. He said, “TNG proposed Technoform due to its unique portfolio of spacer systems, providing the ideal product solution for this high-end glass unit.”
LeBlanc continued, “Due to Technoform’s industry reputation as a leader in providing thermal IGU spacers, thermal breaks and isolators, the product was readily accepted into the design. Overall, with the two layers of high-performance low-e and the warm edge spacers provided, we were able to achieve the wall performance desired by the design team and consultants.”
“The overall exterior visible quality and glass flatness was a huge concern. Therefore, the outer lite was specified as 2-by-8mm laminated glass to lower the risk of visual distortions – all intended to provide a higher level of flatness on the exterior surface,” emphasized Schulte.
SOM’s associate Eric Pasche, AIA, added, “Laminated glass was also preferred by the client to provide an additional level of safety in the event of glass breakage.
“The architectural team at SOM also was very concerned about color matching between flat, concave and convex shaped panels,” noted Schulte. Anisotropy, which is the property of being directionally dependent, also was an important consideration.
Custom coatings met the architectural vision and aesthetic intention. Schulte elaborated, “Clarity developed a plan with G-Crystal and TNG to customize a low-e (coating) for the surface #5 vs. surface #4 to receive similar reflection and solar performance values throughout the glass.”
Pasche clarified, “This strategy was only used at the concave units. Most of the tower has the low-E coating on the #4 surface. The surface stresses for concave curved glass would cause the typical low-e coating on surface #4 to stretch and break, so a custom coating was developed for surface #5 on the concave units to create the same visual effect as the typical units.”
Schulte continued, “This let the building envelope look shiny from a distance, but more transparent and neutral up close. From a spacer perspective, the color was specified in black to have the spacer virtually disappear into the window system without any perimeter reflection.”
TNG produced the units, working closely with Clarity’s inspection process and team. “The owner required a 100 percent inspection of fabricated glass, which TNG accepted and welcomed to prove the high level of production quality and workmanship on the final glass. Clarity managed to keep all the loose ends together to develop, produce, inspect and deliver a tailor-made product from China at the highest aesthetic and quality standards,” said Schulte.
707 Fifth, 707 5th St. SW, Calgary, AB T2P 0Y3 Canada
• Architect: Skidmore, Owings & Merrill LLP (SOM); Chicago
• Construction Manager: EllisDon Corporation; London, Ontario
• Project consultant and manager: WSP (and formerly Pivotal); Toronto
• Glazing system – designer, manufacturer and installer: Contract Glaziers West Inc.; Calgary, Alberta
• Glazing system – manufacturer’s representative: Clarity Architectural Products; Toronto
• Glazing system – glass fabricator: Tianjin North Glass; Tianjin, China
• Glazing system – glass coatings: G-Crystal Glass Group Corporation; Beijing
• Glazing system – spacer: Technoform; Twinsburg, Ohio
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