The renovated Ken Soble Tower in Hamilton, Ontario, has officially received its EnerPHit certification, becoming the world’s largest residential building retrofitted to the Passive House standard. Also recognized as the first retrofit of its kind in North America—and Hamilton’s first Passive House tower—the 18-story building features fiberglass frame windows from industry-leading, Canadian manufacturer, Cascadia Windows & Doors.

“The Ken Soble Tower is an incredible project,” says Mike Battistel, president of Cascadia Windows & Doors. “It demonstrates how existing tower buildings can be upgraded to high-performance levels.”

Part of the CityHousing Hamilton Corporation’s (CHH) portfolio, the upgraded Ken Soble Tower features nearly 260 triple glazed, Passive House Certified windows for over 12,000 square-feet of glazing. These high-performance fiberglass frame windows achieve R-7.7 (U-0.13) for fixed windows and R-7.1 (U-0.14) for the door-sized tilt and turn windows, used for the building’s Juliette balconies.

Design by ERA Architects—an innovator in tower retrofits—the building’s high-performance building envelope utilized mineral wool exterior insulation from Rockwool, as well as Cascadia’s windows. But to achieve the project’s performance level, the project team needed a creative approach to assembling these components.

“The envelope detailing—specifically where the windows meet the other envelope components and the structure—are really interesting on this project,” explains Battistel.

To shift the windows into the exterior insulation layer—and improve the overall envelope performance—the design team utilized low-conductivity fiberglass brackets for the windows to sit on. This innovation helped limit thermal bridging in the envelope assembly, further reducing operating costs and increasing occupant comfort.

“The entire team deserves recognition and congratulations for completing this ambitious project,” says Battistel. “From our manufacturing team and project managers, to ERA, the installers, and CHH, the incredible work and collaboration shown is nothing short of inspiring.”