Poiesis Architecture, a firm designing functional, beautiful, and sustainable spaces, while seeking opportunities for public facing elements in each project, proudly introduces West Don Ravine Passive House, Toronto’s first PHIUS Certified Passive House home. Situated in a north Toronto neighbourhood abutting the Don Valley ravine, the West Don Ravine Passive House project began on a personal note for principal architect Gregory Rubin, who conducted the project on behalf of his parents. Leveraging more than 15 years of experience working on high-end residential and institutional projects, Rubin’s parents entrusted him with the creative freedom to design his first ground-up structure.

As long-time residents of the property and the neighbourhood, and deep admirers of the bordering ravine, the clients chose to downsize towards retirement while remaining on site. They envisioned replacing their existing 3-story home with a new, more manageable bungalow-style structure that would better suit their future needs. Motivated by their experience during a destructive ice storm in 2013, the couple also prioritized designing a home more resilient to the effects of climate change.

Passive design
While the achievement of Passive House certification was never the original goal, Rubin’s embrace of its concepts, and environmental stewardship in general, soon shifted the design’s focus in an exciting direction. Upon realizing that the precise standards of Passive House certification were achievable and within grasp, its gravitas made it a primary consideration of the project.

Passive House standards are widely regarded as some of the most rigorous voluntary energy-based benchmarks in the design and construction industry. Buildings certified under these standards reduce heating and cooling energy consumption by up to 90 percent. These internationally recognized designations are rooted in science-based energy principles.

“Passive design presupposes that the future of our power sources will be electric and renewable,” explains Gregory Rubin, OAA, LEED AP, Principal and Founder of Poiesis Architecture. “The ultimate goal is to future-proof your building, and the first step towards doing that is to create a super-insulated building that dramatically reduces the demands of the mechanical systems.”

A nature-connected mandate
At the heart of the project, the design prioritized a connection to the ravine from any vantage point in the house, with a focus on achieving greater connections to surrounding outdoor gardens that gradually slope towards the ravine. Simultaneously, the mandate prioritized the maintenance of indoor and outdoor spaces that are large enough to cater to family gatherings, particularly at the newly designed ravine walkout level. Those preferences dictated a program that needed to address ecological regulations related to working within the footprint of the previous building, and Poiesis increased the surrounding vegetation by replacing hard materials with native plants, fostering a more integrated landscape.

This commitment to environmental stewardship reflects Poiesis’ broader approach, which aligns with current architectural trends that increasingly consider the impacts of buildings on both the environment and human health. This philosophy extends indoors, with a focus on healthy breathing systems and material choices.

“I would describe the design as ‘modernism harmonized with sustainability’, where health-focused principles go hand in hand with comfort and energy efficiency,” explains Rubin. “As a practice, we focus on modern design, but with a keen interest in minimalism, clean lines, and exploring ways to connect the indoors with the outdoors.”

Invisible barriers
The West Don Ravine Passive House is organized across two distinct levels: a south-facing street-level entry, and a north-facing lower ravine-level walkout. The upper level features a garage and the principal bedroom, with a central mezzanine backed by terracotta paneling that delineates the transition between the street-facing and ravine-facing programs. Upon arrival in the foyer, passage along the east-west line reveals a cut in the floor, providing a view of the lower-level spaces. To the south, a sunken garden extends from the upper level to the lower level, channeling abundant natural light through a large, expansive window that bathes the social spaces in soft daylight, filtered by the terracotta screen above.

Opening to the north, all the main living spaces on the lower level offer views towards the ravine courtesy of a full glass wall. This northern glass facade connects the indoors with the surrounding nature, while external terraces extend beyond a newly created loge-style porch and gradually descend toward the ravine. Within the borders of original retaining walls, abundant new landscaping enhances the connection between the home and its natural setting.

“The landscape cascades down towards the ravine without guardrails, thanks to a gentle slope design,” explains Rubin. “It consists primarily of perennials that enhance the ravine’s natural ecosystem, with native plants selected that are particular to the area.”

Innovative material solutions
Drawing on key principles of Passive House design, the architect overcame the challenges of working with the north-facing façade. With thoughtful material choices and a meticulous evaluation process, the fully transparent glass wall was achieved without compromising warmth. On the south façade, windows are thoughtfully positioned to invite natural light and frame views of the sky, while the north-facing floor-to-ceiling glass provides expansive connections to the ravine and its natural landscape, ensuring that the home feels open to both horizons.

Rectangular in form, and divided into functional quadrants, the integration of the West Don Ravine Passive House’s indoor and outdoor spaces is a product of holistic design strategies. Passive techniques for heating, cooling, and daylighting are paired with materials like terracotta and exposed concrete, integrated both indoors and outdoors to create a cohesive and harmonious design. Naturally-colored terracotta baguettes and tiles, along with blue-tinted terracotta, frame the design, while locally sourced limestone is used in social spaces, and ash wood flooring highlights more private and functional areas. In the primary bedroom, Jack pine and white pine are used for flooring and wainscoting, creating a treehouse-like retreat that reflects materials personally meaningful to the occupants.

“These opportunities emerged and were harnessed as the design unfolded,” notes Rubin. “For instance, we decided to apply the insulation on the exterior of the envelope, which opened the door to exposing the concrete foundation wall on the inside.”

Heartfelt conservation
Demonstrating a commitment to conservation practices, Poiesis Architecture integrated comprehensive research and team development from the project’s inception. To implement the home’s HVAC system, they assembled a team that included technical engineers experienced in Passive House standards and well-versed in envelope design. Additionally, a specialized home automation consultant was engaged to install shading and lighting systems, enhancing the home’s connection with nature by creating a sort of theatre for the ravine setting.

Adhering to Passive House principles, the design incorporated super-insulated, airtight assemblies, resulting in interiors that are exceptionally comfortable in terms of both temperature and humidity control. Poiesis also focused on maximizing natural light intake through carefully inserted openings, mindful that each additional aperture impacts the insulated exterior envelope’s performance. Collectively, these innovative design choices have cleared the way for an all-electric future.

“The emphasis on Passive House design isn’t about simply applying the latest and greatest technology, but rather on committing to building something durable, resilient, and well-insulated,” explains Rubin. “As a consequence of those initiatives, both operational and consumption demands can be significantly reduced.”

A learning process

After initiating the project with demolition and site preparation, the COVID-19 shutdown in 2020 slowed the construction process. Seizing this unexpected downtime, Rubin took the opportunity to deepen his understanding of plants native to the site. To further this effort, the team collaborated with an urban forestry consultancy specializing in ravine stewardship and ecological restoration. Inspired by this collaborative process, Rubin earned a pollinator steward certification.

“Following that experience, we’re proud to have shared a ravine stewardship program that provides neighbours with a greater understanding of the ravine that defines the character of the street,” he says. “From start to finish, this project has expanded my sense of what our firm can offer such sites, both as architects and as stewards of the land on which our buildings sit.”