Sixties-era Hamilton tower gets a Passive House refit

Sitting kitty corner from the Royal Hamilton Yacht Club, a centennial-era tower is undergoing a remarkable transformation.

Cold floors, leaky windows, patchy heat and odd space planning are all on the chopping block as one of the most stringent caterpillar-to-butterfly methods, the Passive House Standard, is turning the 18-storey Ken Sobel Tower into a model of 21st-century efficiency.

“This is in City Housing [Hamilton]’s portfolio,” Graeme Stewart, of heritage specialty firm ERA, says. “City Housing has new leadership, a new team, a new CEO … for new construction and retrofit, the standard should be Passive House: that’s where it is in Vancouver now; that’s where it’s going.”

The thing is, it hadn’t gotten to Ontario, until now: “This is the first tower retrofit in North America and it will be one of the largest of its kind in the world when it’s done, so it’s a real milestone,” Mr. Stewart says.

Of course, it won’t be a milestone until the stern, hard-as-nails, Teutonic types at the Passive House Institute (PHI) in Darmstadt, Germany say so. And it ain’t easy: A glance at the 25-page document available at Passive House Canada’s website reveals enough charts, graphs, numeric tables and terminology such as “pressure test,” “extensive leakage detection” and “thermal bridge loss coefficients” to frighten off all but those employed at NASA’s Jet Propulsion Laboratory. But, look a little closer, and certain, real life phrases start to appear: “All rooms … must have one operable window”; “it must be possible for users to regulate the interior temperature”; and “[t]he ventilation system must not cause uncomfortable draughts.”

That’s because all of the aggressive tables and numbers boil down to simple livability, says Mr. Stewart: “It actually really mitigates all of those comfort issues, it’s really great for living in.”

Yes, living will be easy for the building’s new occupants when they move in (it’s being converted to senior’s housing, with a percentage of suites barrier-free) but, in the meantime, the PHI will conduct multiple reviews, collect photographic evidence and require ongoing tests to prove the building has achieved certain levels of energy efficiency.

During a recent walkabout, many of the concrete ways – pardon the pun – that will achieve this were clearly evident. While some of the 1967-era white glazed brick is still visible, much of the façade has been covered with an air barrier consisting of a hand-troweled, cementitious layer. That will be followed by a drainage layer, six inches of mineral wool insulation and then the “rendered finish” of white stucco, which will “reference” the original brick, Ya’el Santopinto of ERA says.

“On the interiors,” she continues, old drywall and “nominal” amounts of insulation have been removed and replaced with “four inches of mineral wool and then a vapour barrier and then drywall; so really what we’ve done is sandwiched the existing wall assembly.” All of this will achieve an R-value of 38, and ERA has been working closely with construction contractor PCL to expedite the process so the project stays within budget (it’s not as if there are standardized panels that can be slapped onto 1960s towers to achieve the same result; in many ways this is technology being developed on the fly, which, Mr. Stewart says, creates “a huge opportunity” for a manufacturer to invent prefabricated PHI-certified panels).

To rid units of cold floors, the biggest culprits, balconies, have been removed and will be replaced by Juliettes. That’s because while the Swedes have figured out how to retain balconies using “off-the-shelf products,” it would’ve been too costly to import those products to Canada. “For the next one, we’d love to keep the balconies – a lot of people love their balconies and we don’t want this to be about taking out people’s balconies – but that requires new technical solutions,” Mr. Stewart says.

Standing inside one of the barrier-free units and looking out to the unseasonably cold, grey day framed by the made-in-Canada, PHI-certified, triple-pane window, I ask the ERA team about cost. How much more can building owners expect to pay to bring half-century old buildings up to PHI standards?

“It really depends what you’re comparing it to,” Mr. Stewart says. “If you’re doing a deep energy retrofit, it’s actually three- to five-per cent [more] … because the mechanical costs are way less in a Passive House because you need a quarter of the capacity.”

“The primary goal,” Ms. Santopinto says, “is to create healthy, comfortable spaces.” A third party reviewed the building and found that “if the heat went out in deep winter for four days, compared to an [Ontario Building Code] building, people would be able to stay in here for several days before the temperatures dropped, whereas in an OBC building they’d be out in several hours.” And, since ERA modeled the Ken Sobel retrofit using climate data for 2050, when extreme heat and humidity will also be a problem for the Golden Horseshoe, this would probably apply to summers as well.

Standing on the top floor – where new windows will frame a beautiful, blue view of Hamilton Harbour – it becomes all too clear that these types of conversions, while rare and almost alchemistic today, must become the norm.

“People forget that tearing down a building like this is millions and millions of dollars,” Mr. Stewart says. “There’s a lot of abatement work around asbestos that we’re doing and that would have to be done anyway if you were tearing down. The other side is the carbon issue: 6,000 tons of embodied carbon go into the concrete frame. Build a new one, even a Passive House one, and it would take longer than the life of that building to make that back.”

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