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Undulating Modern Glass Tower

Guardian Glass’ SunGuard coating meets high-performance requirements on Toronto tower

Guardian Glass May18
Photo: doublespace photography

Auburn Hills, Mich.-based Guardian Glass’ SunGuard coating on low-iron bent and flat glass helped Hariri Pontarini Architects, Toronto, and the building team for 7 St. Thomas St. in Toronto, to create an undulating, modern glass tower, while still meeting performance requirements. The unique structure is built on top of six historical Victorian townhome façades that were original structures on the building site.


In addition to building six stories over the original structures on a relatively congested job site, the building design called for curved, insulating glass installed in convex and concave elevations. The insulating glass units (IGUs) incorporate a high-performance, low-E coating on tempered and/or heat-strengthened glass that included white frit lines that created a gradient fade. This design created a number of details that were addressed by East Butler, Pa.-based Standard Bent Glass, the independent Guardian Select fabricator, including:

  • High-performance, low-E coatings can only be fabricated on the concave surface of bent glass.
  • Ceramic frit patterns can only be coated on the concave surface of bent glass.
  • The building elevation features units viewed from both convex and concave.
  • To best feature the white decorative frit, the glass lite with the frit is in front of the lite with the high-performance, low-E coating, and as close as possible to the first surface.

Hariri Pontarini Architects designed this nine-story office tower to make a statement in its upscale neighborhood. The renovated historical structures anchoring the site were intended to stand in sharp contrast to the glass curtainwall rising above. 

The architect specified a high-performance, low-E Guardian SunGuard coating on low-iron glass to ensure energy performance criteria would be met. The glass provides clear views for occupants, while ensuring the white frit pattern gives the undulating glass a further contemporary edge.


Independent Glazier Connection member BVGlazing, Concord, Ontario, brought in Standard Bent Glass to complete the bent IGUs anchored by Guardian Glass' high-performance, low-E SunGuard SuperNeutral 68 coating on low-iron glass. Independent Guardian Select fabricator Trulite Glass and Aluminum Solutions, Woodbridge, Ontario, fabricated the flat IGUs with SunGuard SuperNeutral 68 coating on low-iron glass.

Guardian SunGuard-coated glass gives the project high visible light transmission while helping to manage solar heat gain. The low-iron substrate from Guardian eliminates the green tint seen with standard float glass, meaning that occupants have clear views and the white frit stands out with maximum clarity.

Bobby Chestnut, sales manager of Standard Bent Glass’ decorative division, worked closely with Guardian Glass territory sales manager Jeff Emerich, and recognized early what Guardian SunGuard-coated glass was needed for the complexity of the cylindrical bends and the frit.

“We’ve been bending SunGuard-coated glass for years,” Chestnut explains. “The comfort level is there, no matter the radius or the size. We’ve been doing this long enough that we know which coating is going to deliver the best performance and aesthetic.”

This project was the first time Standard Bent Glass had executed direct-to-glass (DTG) printing, and the company needed to ensure all the elements in the unit were going to perform. BVGlazing created unitized systems to simplify installation.

“The contrast between the solidity of the red brick heritage houses below with the translucent permeability of the glass tower—which steps back and appears to float above the Victorian frontages—highlights both typologies,” explains David Pontarini, founding partner at Hariri Pontarini Architects. “The curved white glass curtainwall affords unobstructed views for the upper levels.”

SunGuard SuperNeutral 68 coating on low-iron glass checked off all the requirements for a convex and a concave bend with the following makeups:

  • Convex View: White gradient frit on the No. 2 Surface (Concave) and Guardian SunGuard SuperNeutral 68 coating on low-iron glass on the No. 4 Surface (Concave)
  • Concave View: White gradient frit on the No. 3 Surface (Concave) and Guardian SunGuard SuperNeutral 68 coating on low-iron glass on the No. 5 Surface (Concave)

“This was great teamwork to deliver a unique, high-performing curtainwall,” says Emerich. “Guardian Glass was pleased to be part of a project that puts on display the possibilities of bending high-performance, low-E glass. The stunning results speak for themselves.”

The building contributes to the urban environment through various features including its high-performance curtainwall. Guardian SunGuard-coated glass brings value to the building by regulating solar heat gain without obstructing the view, which helps the HVAC system manage energy output. The project is targeting LEED Gold certification.

Brian Schulz is marketing manager, commercial, at Guardian Glass North America, Auburn Hills, Mich. For more information, visit