Dedicated to sustainable,
high performance building

Existing Building Upgrade Award

500 MacNab Seniors’ Housing /Ken Soble Tower – Hamilton, ON

Jury Comment: “This project creates an important precedent, given the prevalence of this high-rise residential typology throughout North America. Achieving Passive House (EnerPHit) certification is a remarkable achievement. The loss of individual balconies is unfortunate, given the demographic of the occupants; a challenge for PH projects we hope may be overcome in the future.”

The transformation of 500 MacNab is a ground-breaking project rehabilitating a post-war apartment tower to the Passive House EnerPHit standard. This has reduced the associated greenhouse gas emissions by 94% and created a template for industry-wide housing renewal throughout North America.


The tower was originally constructed in 1967 and by the start of this project had fallen into a state of disrepair to the point of being uninhabitable. An early consideration was whether to demolish the existing structure and build new, or to complete a retrofit and restore the building to a serviceable condition, consistent with today’s standards of durability and performance.

Ultimately, the team chose the retrofit option which extended the life of the existing cast-in-place concrete frame and part of the existing masonry envelope. The environmental impact and embodied carbon of the original construction were not wasted, nor unnecessarily duplicated in a new building. By pursuing a Passive House level retrofit, the ongoing operational carbon emissions of the building were drastically reduced and will support an extended service life.

Setting a Precedent

The first retrofit of its kind in North America, at 18 storeys and more than 7,500m2, the 500 MacNab transformation is now one of the largest EnerPHit certified projects in the world.

The project is the premier achievement to date in realizing the ambitions that are now part of Federal Policy and supported through the National Housing Strategy Repair and Renewal Fund.

Enhancing Performance

The most important strategy for reducing operational carbon is the high-performance Building envelope, which almost doubles the minimum insulation values required by code. Together with high levels of airtightness, this greatly reduces the overall heating and cooling demand. The envelope upgrades include R-38 effective over-cladding, passive-house certified windows and air sealing details to achieve 0.6ACH @50Pa.

Project Credits

  • Owner/developer  City Housing Hamilton
  • Architect  ERA Architects
  • General Contractor  PCL Constructors Canada Inc.
  • Landscape Architect  ERA Architects
  • Electrical Engineer  Nemetz & Associates
  • Mechanical engineer  Reinbold Engineering
  • Structural Engineer  Entuitive Corp
  • Commissioning Agent  CFMS West Consulting Inc
  • Passive House Consultant  JMV Consulting
  • Passive House Certifier  Herz & Lang Gmt
  • Building Envelope Consultant  Entuitive Corp
  • Photos  Doublespace Photography
  • Energy Intensity  145 KWhr/m2/year
  • Reduction in Energy Intensity  91 %