Sophisticated curved glass meets stringent energy targets

707 Fifth Tower in downtown Calgary.

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October 09, 2019 |

Chad Koski

World-renowned architects Skidmore, Owings and Merrill (SOM) designed the façade of the 707 Fifth “AAA” office tower in downtown Calgary, Alberta, to combine convex and concave forms to shape elliptical and undulating elevations. The floor-to-ceiling glass is designed to maximize internal daylighting, minimize unwanted solar heat gain and heat loss, and provide panoramic views of the city and the Rocky Mountains.

The thermal performance requirements included a stringent whole unit U-factor of 0.16 btu/hrft2F (0.91 W/m2K ).

The project’s construction manager, EllisDon, worked closely with glazing designer and manufacturer, Contract Glaziers West Inc., to meet this challenge.  “The façade had a geometry of both concave and convex radius glazing, as well as the east and west elevations’ inverted slope from ground level to the top of the building. All flat and curved glass had to match in color and performance as per the design specifications,” explained Contract Glaziers West’s Steve LeBlanc.

Tianjin North Glass (TNG) was the 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.   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.


Photo: Steve LeBlanc.


A custom, high-performance, unitized, structurally glazed, thermally broken aluminum-framed curtain wall system was designed, manufactured, and installed to precise specifications, in order to bring the challenging vision to reality.

The curtain wall relies on TNG’s state-of-the-art, bent, triple-pane insulating glazing units (IGUs) with two low-e coatings.  Technoform’s bendable, yet rigid and durable, plastic hybrid stainless steel (PHSS) 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.  Furthermore, the color was specified in black to have the spacer virtually disappear into the window system without any perimeter reflection.

“TNG proposed Technoform’s TGI-Spacer M due to its unique combination of durability, high thermal performance and bendability , providing the ideal product solution for this high-end glass unit,” explained Dirk Schulte, formerly with TNG.

According to Contract Glaziers West’s Steve LeBlanc, “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.”

Schulte complimented the solution: “Technoform’s hybrid spacer, made of engineered plastic and a strong supporting stainless steel cover, has been extremely helpful to smoothly fabricate the curved and triple-insulating units with concave and convex shaped bends – without incorporating any additional stresses around the perimeter edge seal of the insulating glass panes.”

In total, TNG suppled 220,000 square feet (20,400 m2) 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.

“The ease of handling Technoform spacers for flat and curved glass units streamlined the production process to an efficient output of units per day in order to meet the high expectations of the client on quality, schedule and delivery time,” he praised.

The project is 27-stories, 564,000-square-feet (52,400m2) and designed to achieve LEED® Gold certification through the Canadian Green Building Council.  It was completed on time for a grand opening in April 2017. Total construction costs are estimated at $200 million.


Company contact information:

Technoform North America

+1 330 487 6600

1755 Enterprise Pkwy

Twinsburg, OH 44087 U.S.A.


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