Modular Passive House construction replaces hospital staff housing that burned down in 2004
Bella Bella is a small community located on Campbell Island between the northern tip of Vancouver Island and Haida Gwaii. Approximately 90% of its 1,500 residents belong to the Heiltsuk First Nation.
In 2004, a fire destroyed the staff housing complex at the RW Large Memorial Hospital, and Vancouver Coastal Health [VCH] needed to construct a replacement facility. At the time, VCH was actively considering changing the performance requirements for new facilities from LEED to Passive House. Buildings certified to Passive House require up to 90% less heating and cooling energy than an average building.
The Bella Bella project was seen as an opportunity to put this change into practice. An RFP (request for proposal) was issued for a design/ build contract, including a basic program, design criteria and the requirement for Passive House certification
Mobius Architecture had been involved in the assessment of the fire damaged structure, and saw the opportunity for an innovative solution to this challenging project. It sought out Spani Developments, a local company that had worked previously for VCH, but also had experience building homes in remote locations.
It quickly became clear that conventional site-built construction would not work, given the short construction season and the need to barge all materials to the site. The team considered prefabricated panel solutions, but these would also have been vulnerable to weather. In addition, the complexity and precision required for Passive House certification made site construction, and even panel construction, risky. The team then considered volumetric prefabrication, and approached Britco to see whether the program requirements and specifications could be met in its production facility. They could, and so Britco joined the team.
The team realized a significant amount of work would be required to respond to the RFP with drawings and a fixed price. Passive house certification on modular construction had not been attempted in British Columbia before, and the learning curve was steep. Accordingly, we sought out Red Door Energy [and through them] RDH Building Engineering for their expertise in the Passive House methodology and envelope design, respectively. Most important, however, was their ability to train the Britco and Spani workforce who would be responsible for the factory fabrication and site assembly of the project.
Preliminary architectural drawings, details and a product list were completed. At the same time Britco and Spani personnel refined and costed the scope of factory and site work, and Red Door Energy worked on Passive House precertification. The logistics of transportation by truck and barge also had to be understood, and the risks and uncertainties mitigated within a fixed-price quotation. One significant advantage of the volumetric prefabrication approach was that the modules could be pretested in the factory before being shipped to the site.
The considerable attention paid to understanding the scope and preparing the bid was rewarded when Spani Developments won the contract. Detailed design began immediately to take advantage of the short construction window.
Construction of the first modules began as final energy modelling was being completed. Although pre-testing for air leakage was planned for the factory, a number of envelope air seals had to be completed on site. Certification was further complicated by the limited climate data base available at the Passive House Institute, and the fact that Campbell Island gets its power from a diesel generator.
Architectural details were prepared with colour coding to differentiate work that was to be done in the factory and what was to be done on site. RDH provided training on the installation and sealing of membranes and envelope insulation. It was possible for exterior envelope work and interior finishing, such as built-in cabinetry, plumbing fixtures and lighting, to proceed simultaneously, reducing overall construction time.
As each module was finished, it was tested for compliance with Passive House standards.
As fabrication proceeded, a crew was working on site to prepare the concrete pad foundations, a pressure-treated exterior foundation wall, and all necessary site servicing. The HRV was installed in the factory and prepared for the connections on site. Further training of site workers preceded the arrival of a crane and the first shipment of modules by barge.
Construction began in the rain, requiring the planned protective measures to be implemented. The site reviews were completed by the consultants, and the air tests, air balancing and systems testing were done by Red Door Energy. In just two weeks the final exterior work was completed, the units were cleaned and furnished, and residents moved in.
In hindsight, off-site construction was the correct choice, ensuring the precision required for Passive House detailing was not compromised by weather. The lessons learned are transferable, and confirm that innovative approaches can benefit the planet, save energy, increase productivity and improve housing affordability. The leadership shown by Vancouver Coastal Health in promoting Passive House is an example other public and private institutions should follow.
Wood-frame construction with mineral wool and fibreglass insulation and metal cladding built to Passive House standard by Britco LP; Thermoplus 4700 Series windows by Euroline Windows Inc.; split system heat pumps and Comfoair 200 HRV units by Zehnder.
Owner Vancouver Coastal Health Authority
Architect Mobius Architecture Inc.
Structural Engineer CanStruct Engineering Group
Mechanical Engineer ITEC Systems Design Ltd.
Electrical Engineer Opal Engineering
Passive House Consultant Red Door Energy
Building Envelope RDH Building Science Inc.
General Contractor Spani Developments Ltd.
Module Fabricator Britco LP
Photos Britco LP