World’s largest residential Passive House EnerPHit retrofit certified in Hamilton

Ontario Construction News staff writer

Ken Soble Tower in Hamilton is now the world’s largest residential building retrofitted to the Passive House standard – achieving EnerPHit certification – while also marking the first retrofit of its kind in North America, ERA Architects and PCL Construction have announced.

The 18-storey, 146-unit CityHousing Hamilton building has achieved a staggering 94 per cent reduction in greenhouse gas emissions and a 91 per cent reduction in heating energy demand.


At its peak, the total energy required to heat and cool a unit would be equivalent to the energy needed to power three incandescent light bulbs.

“We could not be more thrilled that the Ken Soble Tower project has achieved Passive House – EnerPHit certification,” said Chris Ballard, CEO, Passive House Canada.

“With over 10,000 towers across Canada in need of deep energy retrofits, the team at ERA Architects, PCL and CityHousing Hamilton have shown great leadership and we congratulate them on this tremendous achievement.”

To meet the rigorous Passive House standards, a team specializing in apartment retrofits was brought together, including prime consultant ERA Architects, a Toronto-based architecture firm known for its expertise in low-carbon retrofits and the force behind the Tower Renewal initiative, and PCL, Canada’s largest general contractor with expertise in building revitalization and in-house envelope engineering.

According to the project architect, jt is a ground-breaking project rehabilitating a post-war apartment tower to a Passive House standard – reducing greenhouse gases emissions by a staggering 94 per cent and laying the groundwork for industry-wide, ultra-low energy retrofits needed to maintain thousands of apartments across Canada before they are lost.

“Ultra-low energy retrofits that maintain affordability are not only possible, but critical to preserving and enhancing housing across the country,” said Graeme Stewart from ERA Architects.

The tower was retrofitted to support resident health and climate resilience, with embodied carbon in the building’s structure being saved through building re-use and revitalization of 146 units of affordable senior’s housing. A reconfiguration of all indoor and outdoor spaces was included, to accommodate aging-in-place. Over 20 per cent of apartment suites now meet barrier-free standards, with expanded community facilities that support seniors’ programming.

“The outcomes we’ve achieved demonstrate that high-performance building envelopes are possible on large-scale retrofit projects, paving the way for ultra-efficient retrofits to support a low carbon future,” said Marc Pascoli, vice president and district manager of PCL’s Toronto District Office.

“Achieving EnerPHit certification reflects the expert rigor, best practices and collaborative efforts between our client, consultants, trades, and PCL.”

Building performance was achieved in part through an ultra high-performance building envelope, with exterior and interior insulation that meet stringent airtightness requirements, triple-glazed windows, and heat recovery in all building penetrations. Obsolete and unhygienic HVAC systems have been fully modernized to provide fresh air to each suite.

To achieve EnerPHit certification, the team had to confirm that the final building was constructed and performed as designed. This was achieved through a comprehensive air tightness testing and quality management program that was developed by the project team and guided by PCL’s in-house envelope engineer and construction team. The effectiveness of PCL’s quality program was demonstrated by final operational whole building airtightness tests that bettered targets by more than 50 per cent at 0.235 air changes per hour (ACH) at 50 pascals pressure (Pa).

Through a two-year monitoring process, the Ken Soble Tower will become a teaching tool, offering real-time lessons in retrofit design. CHH, in partnership with the University of Toronto, ERA and PCL, will study and measure the impacts of the building on its residents and surrounding environment, including building performance, resident health and safety, and economic impacts

“We are very proud to have worked alongside CityHousing Hamilton to realize the renewal of the Ken Soble Tower as affordable and resilient housing, and one of the largest EnerPHit projects in the world,” says Graeme Stewart, Principal, ERA Architects. “Showcasing that low carbon retrofits are the path for a resilient future, offering health, safety and comfort to residents, the Ken Soble Tower is a true model for addressing the growing climate and housing crises of our time.”

As the oldest high-rise multi-residential building in CityHousing Hamilton’s (CHH) portfolio, Ken Soble Tower at 500 MacNab Street North has stood proud in Hamilton’s West Harbour neighbourhood since 1967. The building was fully occupied until 2014 when a mix of aging infrastructure and increasing capital costs led it to fall into disrepair.


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