Built in 1932, the original home had been cut up and rented as student housing for many years. The new owner engaged Ian Robertson of ABBARCH Architecture to transform the building into a quiet house with superior energy efficiency and resilience. Passive House design was not an initial goal, as the client was unfamiliar with the standard, but the client’s performance requirements dovetailed so neatly with Passive House that certification was set as an objective.
Robertson and Pierre-André Santin of MIZU Passive House Consulting worked closely together, along with builder Erik Olofsson, to create an aesthetic solution that also met the client’s performance goals. The numerous challenges presented by the existing structure resulted in a decision by the client to build a new home. The city of Vancouver allows for accelerated permits for Passive Houses, so a compliant design would also provide a benefit by greatly reducing the time to start construction and hence to finish the project.
Designed to intelligently push creative boundaries, the 3,200-ft2 structure includes a two-level above-ground residence with a basement suite that can be rented as a separate unit. Its design incorporates large north- and south-facing glazing areas to create a seamless connection to the outside, and thick opaque east and west walls to conceal all services, mechanical systems, storage, and neighbours.
Initially, the owner worried that the Passive House requirements might result in limits on the size and number of the windows. A concentrated effort by the architect and consultant retained all the glass contemplated in the concept design. The design progressed with careful attention to the numerous structural options, in terms of cost, embodied carbon, and aesthetics. Eventually the team selected prefabricated structural insulated panels (SIPs) for all of the envelope.
Preserving the rental-suite option suggested separate, dedicated services for ventilation and water heating, using two HRVs and one heat pump water heater but two storage tanks. In addition to high-MERV filters, the ventilation system is fitted with a carbon filter—a small extra cost that makes a huge difference, especially during the increasingly common wildfire seasons.
Passive House Metrics
Cooling and dehumidification demand
Primary energy demand
Primary energy renewable (PER)
0.6 ACH₅₀ (design)
The basement-level walls conventionally would have been built in concrete, but SIPs attached to a concrete raft slab cost about the same and result in less embodied carbon. The below-grade assembly includes magnesium oxide board, for its water-resistant properties, and a self-adhering membrane bathtub for waterproofing and airtightness. This membrane is taped to the above-grade air-and-vapour barrier membrane for continuous airtightness.
A long-span mass-timber-concrete-composite floor structure efficiently allows the ground-level space to flow freely from the front yard to the back. Split levels create an open-plan ground floor juxtaposed against a deliberately private second floor with a planted wall shading the roof deck and south-facing bedrooms.
The roof includes German-made tempered glass tiles enclosing PV cells. Currently under construction, the project is scheduled for completion and certification to Passive House Plus in 2019.