The annual Passive House Canada Conference has long been a showcase and progress report for the Passive House standard in Canada. More than just providing case studies demonstrating its resiliency and efficiency, professionals from around the world also come to detail the many benefits of Passive House building to health and well-being. Others highlight some of the remaining headwinds that Passive House practitioners face. Most notably, these include implementing passive methodologies in novel building typologies and retrofits, as well as overcoming challenges with project finance.

There was something new for the 2024 conference, however, as the event was actually held within two recently completed Passive House buildings on the campus of the University of Victoria, in British Columbia, that comprise the university’s new housing and dining complex. Consequently, those in attendance had the opportunity to experience the benefits of Passive House firsthand. That these buildings—Čeqʷəŋín ʔéʔləŋ (Cheko’nien House) and Sŋéqə ʔéʔləŋ (Sngequ House)—played host to the 2024 conference felt appropriate, as multiple sessions from previous Passive House Canada conferences had focused on the unique challenges involved in their design and construction.

As I reported previously in an article on the Bâtiment Passif Québec (Passive House Quebec) website, attendees not only had the chance to explore these completed buildings during the day; they even had the opportunity to stay in the Cheko’nien House and to experience the comfort of sleeping in a Passive House at night. I obviously chose this option. I knew it was going to be comfortable from a thermal and air quality point of view, but the building also had cozy rooms and big, airy common spaces with lots of daylight and windows.

Marine Sanchez, a senior consultant with RDH Building Science, notes that the communal and non-residential areas were designed with far more glazing than the individual rooms for several reasons. On the one hand, this strategy helped to balance energy budgets with the more judicious placement of windows within the students’ personal rooms. On the other hand, the strategy helped to emphasize the design team’s desire to use building orientation, massing, and landscaping to more fully integrate the building into the common spaces that permeate the university’s campus. Sanchez observes that the common areas within the building, even on the upper floors, are meant to keep occupants feeling connected to the public areas of the campus.

Passive Solutions with ROCKWOOL

With a wide array of challenging, high-performance goals, the project was complex, necessitating a very holistic approach. The rigorous energy targets may have been a primary concern, but the project teams also had to balance additional considerations that factored significantly into the design, including fire protection, moisture management, climate resilience, durability, air quality, and more.

Stone wool insulation provided the key to meeting a wide variety of identified objectives. The project incorporates eight inches of ROCKWOOL Cavityrock® continuous exterior insulation into the exterior wall system to serve a number of important functions. Primarily, the stone wool meets the need for high insulation levels, which passively work to maintain consistent temperatures inside the building, providing occupants with reliable thermal comfort while reducing demand on energy-reliant mechanical systems. Stone wool also served to address long-term resilience and durability, particularly as the buildings will need to stand up to more extreme weather events due to the impacts of climate change. Creating a durable structure with robust materials and a higher-performing building envelope will potentially help reduce maintenance and/or remediation/replacement/repair costs during the building’s long-term operation, while also preventing infiltration of outdoor allergens and air pollution, resulting in improved indoor air quality (IAQ).

Victoria’s coastal and temperate climate increases the risk of temperature extremes and heavy precipitation, based on the PCIC 2050 climate modelling. Even amid construction, the area experienced an atmospheric river event, a condensed band of water vapor that produces heavy amounts of rain or snow that typically stalls over land to create the potential for record precipitation and flooding.

To respond to these conditions and to futureproof against more extreme events, the design team focused on a ventilated rainscreen strategy. Because stone wool insulation is vapor permeable and allows any moisture to dry to the outside, it will help keep the wall system dry, mitigating any potential moisture-related issues over the life of the building. Stone wool’s inorganic composition and resistance to mold and mildew also contribute to the buildings’ excellent IAQ. 

With moisture addressed, fire protection was another aspect pertaining to building resiliency that the design team aimed to address. Stone wool was selected since a non-combustible insulation product was desired. In addition to the rainscreen, stone wool insulation also satisfied the requirement for a fire-rated wall assembly where an exterior canopy was incorporated to create a covered loading area on one of the buildings. Stone wool products offer high fire resistance to temperatures up to 1,177°C (2,150°F), and the specific products chosen boast the lowest possible smoke development and flame spread index of 0/0 when tested to ASTM E84 and CAN/ULC S102. Moreover, stone wool achieves its fire resistance due to its natural stone composition, without the need for added chemical flame retardants. When it came to product selection in all applications, use of natural, healthy, and sustainable materials was a goal consistent with the university’s Sustainability strategy.

From a contractor perspective, stone wool provided a number of advantages that helped during the insulation install. The density and dimensional stability of ROCKWOOL Cavityrock® allowed for excellent handling. As the insulation was installed in two 4-inch layers, these two characteristics also ensured tight seams to prevent gapping, which made it possible to achieve a more precise install. The dimensional stability and tight fit also provide confidence that the material will stand up over time, with no compromise to the building’s thermal, fire, or acoustic performance. Density once again factored into another big benefit to the install teams: ease of install. The ROCKWOOL Cavityrock® boards were ideal to cut and custom fit, as needed, and worked well with other components including the steel clips and galvanized girts. The properties and benefits that stone wool insulation offers resulted in time saved on the jobsite, helping install teams adhere to the tight construction schedule.

Ultimately, the use of ROCKWOOL Cavityrock® stone wool insulation allowed the project team to meet their most ambitious goals from a myriad of perspectives. The material assists with fire protection and moisture management, ensuring long-term durability while promoting enhanced IAQ. Stone wool’s superior insulating power also helped significantly reduce operational carbon, allowing these two UVic buildings to meet even the most rigorous of performance standards, while providing quiet and comfortable spaces for students, staff, and visitors.

Top photo courtesy of Perkins&Will.