In early 2015, Vancouver Coastal Health Authority issued a public Request For Proposal seeking staff housing solutions in Bella Bella, British Columbia, before the end of September 2015, built to Passive House standards. And since Metric Modular never shies away from an opportunity to innovate, we put our heads together to figure out how to build Canada’s first multi-unit modular Passive House.
In order to be a certified “Passive House”, a building passes a rigorous quality assurance processes and meets strict criteria, including space heat demand, primary energy demand and pressurization testing. When these criteria are met, energy consumption and greenhouse gas emissions are reduced by up to 80 percent.
Aside from the challenge of building to Passive House standards for the first time, there were several additional challenges that required some innovative thinking from the Metric Modular team. We had to build on the existing foundation and, since the original building had been destroyed by fire, there was also an urgent need for the building to be completed quickly so that Vancouver Coastal Health Authority staff could move in as soon as possible. As well, Bella Bella, BC experiences some of the wettest weather conditions in the province and this location has extremely limited access to trades and materials.
By building to Passive House standards, this 6-unit townhouse complex has remarkable energy efficiency. Even on the coldest day of the year, each unit will have a peak heating load of around 600 watts – the equivalent of six 100-watt lightbulbs, with no additional heating needed, while the Heat Recovery Ventilator provides fresh air to the building which is replaced at least every three hours.
Combining modular construction techniques with Passive House standards was a natural fit, especially since one of the key components of achieving Passive House standards is the airtightness of the building. Because we were able to test each module for airtightness before it left our off-site construction facility, the amount of rework associated with this level of standards was drastically reduced. In fact, it’s estimated that the project would’ve taken two years is build using traditional on-site construction methods compared to the seven months it took us from start to finish.