From single-family homes to high-rises and mass timber, RDH’s Sherman Wai traces Passive House’s rise into mainstream construction
Chief Leonard George Building. Photo Credit: GBL Architects
Over the past decade, Passive House moved from single-family homes to complex, large-scale buildings, from boutique to code, and from imported components to a domestic supply chain. Few practitioners have seen that shift as closely as Sherman Wai, a Senior engineer and Passive House consultant and certifier with RDH Building Science.
Wai is an associate and Passive House consultant with RDH Building Science in Vancouver. Over more than nine years with the firm, Wai’s work has evolved from Passive House design and PHPP modelling to certification, site review, and airtightness testing.
When Wai joined RDH nine years ago, the firm’s Passive House team in Vancouver was small. Much of the early work focused on single-family homes and townhouses. Since then, he has watched his team grow and the work move into mid-rise and then high-rise, spreading in code from Vancouver across BC and into Massachusetts.
“They’re modeling their approach based on what they’ve seen in Vancouver and it’s pretty exciting to see that,” said Wai.
Wai and the countless architects, engineers, educators, advocates, and policy makers have helped the industry and the code evolve to tackle sky scrappers, community centres, fire halls, and increasingly complex civic and residential projects. There are now over 220 Passive House certified projects listed on the Passive House Canada website and countless more Passive house adjacent or inspired projects across the country.
“The standard was originally developed around single-family buildings,” said Wai. “What we’re doing now is applying it to completely different typologies, and figuring out what needs to change to make it work.”
Simpler Smaller Times
In its early years, Passive House in Canada, primarily in British Columbia, was driven by a small group of highly motivated practitioners and clients. Projects were typically single-family homes or small multi-unit buildings, and the teams involved had actively chosen to pursue the standard.
“It was a lot easier in the beginning,” Wai said. “The people who knew about Passive House were the keeners; they understood the principles, and they wanted to put it into practice.”
More Passive Problems
As Passive House moved beyond early adopters, alignment across teams became harder to maintain.
“I think as you scale up, the hard part is convincing people who don’t necessarily believe in the principles,” Wai said. “They’re on the project, and you have to navigate around that.”
These projects introduced new challenges and became intricate jigsaw puzzles. In the early days, the pieces fit together easily. Teams typically relied on certified components – windows, ventilation systems, and assemblies that had already been tested and validated against Passive House requirements, said Wai.
As Passive House moved into larger and more cost-sensitive projects, teams began looking for ways to cut upfront costs.
“We see a lot more teams trying to make non-certified systems work,” Wai said. “A lot of times, those types of systems just don’t perform as well.”
What appears to be a simple substitution can quickly become a complex problem. Without certified performance data, components often need to be modeled independently, then tested within the broader energy model, said Wail. Small performance gaps must be gained elsewhere each introducing new constraints.
“To offset that, it could mean adding three inches of exterior insulation,” said Wai. “But then you run into a different set of problems, because a lot of cladding systems aren’t designed for that kind of depth.”
Unlocking the Code
The complexity of the projects grew as the code and bylaws incorporated Passive House by name or Passive House’s performance metrics. In 2014, Passive House was first embedded into Vancouver’s rezoning policy, tying certification to project approvals. In 2016, the City then codified its direction through the Zero Emissions Building Plan, shifting toward performance-based outcomes. A year later, the Province of British Columbia introduced the BC Energy Step Code, translating that approach into a phased system of energy performance requirements.
“What Passive House did was it helped transform the building code into a performance based code,” said Wai. “And now with the step code, it’s all performance based TEDI [Thermal Energy Demand Intensity] and TEUI [Total Energy Use Intensity]…and these metrics are all modeled after the Passive House standard.”
At the same time, the shift to performance-based code did not eliminate friction with the code. Passive House targets very low air exchange rates to minimize heat loss, while building codes often require higher ventilation rates to meet health and safety standards.
“Passive House generally wants us to aim for around 0.3 air changes an hour,” Wai said. “But to comply with building code, we need to ventilate like three times that. And when you ventilate three times that, everything else has to be so much more efficient just to compensate.”
Building the Industry
In the early years, many Passive House projects relied on imported components. High-performance windows, ventilation systems, and other critical elements were often sourced from Europe, where the standard was more established and supply chains already existed. As Passive House became codified, homegrown Canadian companies and foreign companies set up Canadian manufacturing and production of Passive House certified components.
“We developed this really vibrant industry and competitive market here that was just not present 10 years ago,” said Wai.
Canada’s Passive House supply chain is increasingly built domestically. Although ownership spans both Canadian and international firms, a growing group of Canadian-owned manufacturers have set up shop or adapted their products to provide Passive House components. Innotech Windows + Doors, Alumilex, Euroline Windows, Cascadia Windows & Doors and Oxygen8 now produce high-performance windows, and ventilation systems within Canada.
“What’s really exciting about all these companies is that they export to the United States,” said Wai.
Beyond Energy
As Passive House reshaped how buildings are designed and built, attention is now shifting from operational performance to embodied carbon. Again Vancouver, despite political efforts to curtail Vancouver’s green building leadership, is spearheading requirements to quantify and reduce embodied emissions in new buildings.
Vancouver’s embodied carbon policy, approved in 2020, is anchored in a target to reduce emissions from construction by 40 percent by 2030. Beginning in October 2023, Vancouver requires whole-building life cycle assessments for large buildings, with projects required to meet embodied carbon limits. Projects can either meet an absolute cap or demonstrate performance relative to a project-specific baseline, with emissions not exceeding twice that baseline.
One of the most significant shifts to limit embodied carbon is the growing use of mass timber, including cross-laminated timber (CLT), said Wai. Unlike conventional concrete and steel systems, mass timber stores carbon and can significantly reduce the emissions associated with structure. For Passive House projects, this creates a new kind of integration challenge – another jigsaw puzzle to fit together.
At the Passive House Canada conference, Wai will present the Chief Leonard George Building, a 9-storey mixed-use residential project with a daycare on the first floor, where CLT floor structures and prefabricated CLT-based wall panels from Intelligent City helped lower embodied carbon and meet Passive House energy requirements.
The CLT introduced its own construction challenge, said Wai. The panels had to stay dry. Not an easy task in rainy Vancouver. The team had to think carefully about how panels were protected as they arrived on site and as the building went up. Ideally, each floor would be enclosed before the next was built, but the sequencing was not always that clean, creating lessons for future mass timber Passive House projects, said Wai.
Passive House has shown over the last ten years that building performance can move from practice into policy, supply chains, and code. The next decade will test whether that same discipline can be applied to the full carbon accounting of buildings, the circularity of materials, accessibility for all, resilience in a hotter and more volatile climate, and affordability through cycles of economic upheaval.
A decade from now, practitioners like Wai may look back on this moment the way he looks back on Passive House’s early years: as the easy days.
