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Canadian mid-century towers can have a high-performance future

Don Procter
Canadian mid-century towers can have a high-performance future
DON PROCTER — Graeme Stewart, principal of Toronto-based ERA Architect, told delegates, at a recent seminar presented at the Facades Conference on high-performance building enclosures in Toronto, that 76 per cent of Canada’s mid-century towers were purpose-built rental developments constructed 35 to 50 years ago.

Mid-century residential towers — ubiquitous in many cities across Canada — have been “the backbone of our (public and private) affordable housing system” and can continue that path with the right approach to renewal.

That’s the belief of Graeme Stewart, principal of Toronto-based ERA Architect and founding member of the Centre for Urban Growth and Renewal (CUG+R), a group leading the Tower Renewal Partnership (TRP).

Stewart told delegates at a seminar presented at the Facades Conference on high-performance building enclosures in Toronto recently that 76 per cent of Canada’s mid-century towers were purpose-built rental developments constructed 35 to 50 years ago.

The “big challenge” is that the work on these buildings today often deals with only one measure/symptom, rather than all of the building’s problems because they are seen as “bargain basement construction projects.”

That is not the case, however, of the 52-year-old Ken Soble Tower owned by CityHousing Hamilton, that city’s social housing department. The “poorest performing tower” in TRP’s portfolio, the building is undergoing a major retrofit that includes many repairs and an energy upgrade to meet passive house standards, Ya’el Santopinto, associate, ERA, told delegates at the Repurposing Historic Ontario seminar.

When completed next year, the 18-storey, 80,000-square-foot renewal will be one of the largest EnerPHit certified projects in the world and will create about 145 affordable seniors’ housing units. Twenty percent of the floor plates will be barrier-free — a challenging construction task, said Santopinto.

The paradox is that the budget is modest to meet “extremely high-performance standards. The building needs to be airtight and highly insulated, but we’re also tasked with a low-embodied carbon mandate a post-Grenfell (tower fire in London in 2017) fully non-combustible mandate.”

Initially, plans called for triple glazed windows, a painted-on fluid-applied air barrier and a double-wall assembly to allow close to 12 inches of insulation. Santopinto said there have been some surprises during the building investigation that could impact the initial agenda, including “pervasive hidden mold” within the building envelope.

“It is easy…to design a high-performance building but it is hard to see it through…”

She said the project requires multi-phase air testing in stages from mock-up through to the full building. A clause in the RFP requires the selected building contractor to monitor the air barrier performance.

Santopinto said while the project is an outlier for a visionary client, it won’t be an outlier for long as building codes and standards ramp up.

The ERA architect said if every post-war tower in Canada was retrofitted to passive house standards, there would be about three megatonnes of carbon saved and about 700,000 affordable housing units available for another generation.

Martin Davidson, principal, Diamond Schmitt Architects, told delegates to the seminar about the complex conversion of the Senate of Canada Building, a train station renovated into a seat of government. Along with restoration and rehabilitation of the stone masonry facades, an addition that complements the building’s Beaux-Arts style was completed.

Initial studies for development at the University of Toronto’s historic Knox College in 2011 included a 30-storey tower — a long way from the design chosen. The project — now housing the Daniels Faculty of Architecture, Landscape and Design — is a classic restoration model that incorporates sustainability through its materials and systems.

“This was a challenging project in terms of coordinating the subs,” Katherine Faulkner, founding principal of Boston-based architect NADAAA, told the seminar audience. NADAAA designed the building in collaboration with architect of record Adamson & Associates, landscape architect Public Work and heritage consultant ERA.

“There were a lot of firsts here,” Faulkner said, noting that envelope panel installation was innovative and engineering exterior fins that splay out like pages in a book was tricky.

She said the structure uses the two building cores to support three mega trusses to allow for a column-free 3rd floor studio. The design is based on the Firth of Forth Bridge structure in Scotland.

The Facades Conference was presented by The Architect’s Newspaper based in New York City.

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