The Four Seasons Centre for the Performing Arts sits on one of Toronto's choice sites. The 2,000-seat performance hall, the new home of the Canadian Opera Company (COC), occupies an entire block at the intersection of three of the city's busiest streets: University Avenue and Richmond and Queen Streets. Every day throngs of pedestrians walk by, cars and streetcars zip past, and a subway line rumbles below the $172.3 million facility.
“This site was considered the last really great empty site in downtown Toronto,” says architect Gary McCluskie, a principal with local firm Diamond + Schmitt Architects. “It's center ice.”
That's exactly where the opera company wanted to be. “The COC wanted to participate in the life of the downtown,” says McCluskie. “The location offered them the chance to raise awareness and to attract a new and larger audience.” The COC also wanted an auditorium that offered exemplary natural sound, where the company could elevate its performances by harnessing the power of unamplified voices and instruments.
Previously, the COC was one of several tenants of the Hummingbird Centre, a one-size-fits-all multipurpose hall, an arrangement that left them without a permanent connection to the city. At 3,200 seats, the auditorium was also too big for the COC's needs. “You're just too far away, and the sound is not a natural acoustic,” says McCluskie.
The Building Team's attention, therefore, focused on balancing the COC's conflicting goals of having a new home that embraced the city's hustle and bustle without letting the attendant commotion interfere with the company's performances.
The center's strong visual connection to the city is manifest in the three-sided, four-story glass atrium, called the City Room, whose transparency offers passersby a chance to grasp the center's activity and excitement, which the company hopes will encourage the uninitiated to give opera a chance.
Construction of the City Room's curtain wall resulted in the largest installation of low-iron structural glazing in North America. Low-iron glazing uses only raw materials in its manufacture (conventional glass uses a fair amount of recycled materials), and the elimination of nearly all the iron and other impurities makes it clearer than traditional glass. McCluskie specked the premium glass (added cost: approximately $468,000) from glazing contractor Gartner, which shipped the supersized 7½ x 12½-foot double-glazed panels from its factory in Gundelfingen, Germany, because panels of this size were not available in North America at the time.
To add to the City Room's transparency, the project's structural engineer, John Kooymans, a senior associate at local engineers Halcrow Yolles, suggested taking things one step further and constructing the staircase using glass—including the treads. “We all said, 'Of course!'” says McCluskie. And of course that was easier said than done.
The spanning staircase, which connects floors two, three, and four, has a horizontal run of almost 89 feet and rises almost 30 feet. “There isn't a staircase like this in the world with this size and span and the fact that it's not bearing on anything,” says Kooymans.
The engineers conducted complicated finite element analysis on the entire glass stair structure and tested mock-ups for load-carrying capacity to ensure everything worked fine.
Since no building codes governed this type of staircase construction, provincial code officials exercised extreme caution before granting approval. They were finally convinced when engineers performed a 21,000-pound in situ load test on the bottom flight of the staircase to demonstrate its loading capacity.
Plans for a naturally acoustic auditorium were no less complex, and the Building Team had to address the downside of building at center ice: external noise and vibration from pedestrians, surface vehicles, and subway trains.
To reduce vibration, the auditorium sits on 460 two-foot-square, eight-inch-thick steel plates and rubber pads that isolate it from the main structure. “They act as shock absorbers and basically eliminate any movement and sound from below,” says McCluskie. “It's the first facility in Canada built this way.”
Seating inside the four-tiered, horseshoe-shaped auditorium was pushed as close as possible to the stage for optimum audio quality, with the last row of seats in the top balcony less than 105 feet from the stage. The balcony fronts have tightly rounded panels to reflect high-frequency sounds, while the interior walls have broad scalloped panels to reflect low-frequency sounds. Decorative lighting between panel overlaps are covered by glass plates to eliminate gaps that can trap sound.
“The opera wanted to take its company to the next level, and they needed the proper instrument for that art form,” says McCluskie. “This building is that instrument.”