ERA Architects

Passive House: A new way of working with existing buildings

Cities are at the forefront of climate change. In the fight for a low-carbon future, a new wave of building standards is changing how we think about energy-efficiency and environmentally friendly design. One of the top standards is Passive House.

According to Passive House Canada, Passive House is regarded as the “most rigorous voluntary energy-based standard in the design and construction industry today.” Passive House focuses on limiting the energy needed to heat or cool buildings through high levels of insulation around the building envelope, overall airtightness and whole-house mechanical ventilation. A Passive House’s energy use is significantly lower than its conventional counterpart. 

ERA aims to improve the quality and comfort for residents of GTHA’s postwar towers by transforming the buildings and their surrounding areas into more sustainable, resilient and healthy places. This alignment is one of the reasons we were drawn to the Passive House standard and its applicability to our tower renewal portfolio.

Passive House is an ultra-low carbon standard which is focused on human comfort and air quality. It’s a natural fit for tower renewal, which aims to improve housing quality and health outcomes in aging affordable housing

Exterior of the Ken Soble Tower in Hamilton

Built in 1967, the Ken Soble Tower is the oldest high-rise multi-residential building in CityHousing Hamilton’s portfolio and has been in decline for several years. After considering several options, CityHousing opted to retrofit the building, making significant improvements at a fraction of the cost of a new build.

With its completion, the project will provide residents with improved comfort and control of their indoor environments, and with the ability to withstand extreme climate events into the future. At its peak, the total energy needed to heat or cool each unit will be the equivalent of the energy needed to run three incandescent light bulbs. 

Though a Passive House requires a significant reduction in energy use, the principle is driven by human comfort. The airtightness and increase in insulation mean no drafts, no cold spots and no overheating, equaling an overall more comfortable home for residents.  

The project kickstarts a broader Passive House development program for CityHousing Hamilton’s portfolio at large, making it one of the first organizations in eastern Canada to adopt the Passive House target. 

Applying standards such as EnerPHit – the Passive House certification for retrofits –  to existing buildings can be paired with architectural conservation to maintain their historic integrity, merging a low-carbon future with the cultural significance of the past.

For example, Gemini House is a prototype low-energy retrofit project on the University of Toronto campus. The project is using Passive House approaches to low-energy rehabilitation with the added complexity of being executed within an 1880s Second Empire-style masonry home.

The project achieves a high-performance envelope and low intensity mechanical systems based on Passive House principles. The retrofit will thermally isolate the building into two zones: “core” and “periphery.” The core space comprises rooms expected to be in daily use (kitchen, living room, bedroom, and bathroom), and is therefore heated on a daily basis in cooler months. The periphery spaces (formal dining room, guest bedroom, basement) are kept at a minimal level of heat, but can be warmed on demand. By building this box within a box, energy use was reduced by over 90 per cent.

With a focus on the interior to achieve ultra-low energy transformation goals, the exterior of this listed heritage property was conserved and rehabilitated, with historic windows used to create a ‘second skin’ in front of the new triple glazed windows within.

At a time when climate change mitigation, healthy living environments and improved social resilience are increasingly urgent, ERA is committed to bringing these outcomes to existing building fabric across its conservation, adaptive re-use and tower renewal portfolios.