Passive House Catches On
Through the last decades, the notion of building homes in more environmentally friendly ways has become much the norm. Slowly but surely, at least here in Canada, the conversation has shifted onward from discussing why building technology needs to evolve to discussing how exactly building technology can evolve in order to most responsibly take on its own environmental inefficiencies. What once was considered alternative has now become quite mainstream.
Consider Vancouver Mayor Gregor Robertson’s Greenest City 2020 Action Plan target: “Require all buildings constructed from 2020 onward to be carbon neutral in operations.” Other municipalities around the world are setting the same tone: Melbourne officially became carbon-neutral this year, Copenhagen is pushing for the same by 2025, Seattle by 2050, the entire country of Costa Rica by 2021. According to Vancouver’s Action Plan, greening up construction practices here would mean big positive impact: “the electricity and natural gas that buildings use make up 55% of Vancouver’s greenhouse gas emissions.” Essentially, we need to get building green, and get building green mighty quickly! But we’re in luck…enter, Passive House.
The initial principles that eventually gave rise to the Passive House movement were actually developed here in Canada as part of the Saskatchewan Conservation House demonstration project of 1978. And though the project also stimulated the creation of NRCan’s R-2000 building certification program, the technologies and methodologies were never adopted into any municipal building code, thus slowing the positive momentum inside our borders. Instead, the findings took root in Germany and Passivhaus was born into receptive hands. Today, thanks in part to stricter environmental regulations driven by proactive policymakers, there are about 50,000 Passive House units worldwide.
At the heart of Passive House is not an overly novel idea. Rather than using old tires or straw bales (like some of its green building cousins), and rather than tallying vast arrays of enviro-scoring criteria (like some other of its green certification relatives) Passive House aims to do one thing extremely well. And that is: keep heat where it’s supposed to be.
In order to regulate temperature within the home, a more robust envelope is needed to make the building essentially airtight. Standard framing walls (see my Framing 101 article from 3 July 2013) are made to be super-insulated and double or more the thickness, windows become triple-paned, and solar orientation becomes paramount to success. The need for fresh air and moisture control is managed by a low energy active heat recovery ventilation (HRV) system. The impressive energy savings potential of Passive Houses (many use 90% less energy than traditional, to-code builds) is at the concept’s core, however, neither comfort nor affordability are overlooked.
A Passive House, absent of typical drafts, is kept at a constant temperature ever replenished with fresh air. Warming up the space even further literally means either inviting over a friend, turning on another light, or even just lighting a candle! How’s that for comfort?
And the costs to build Passive are coming down (as with any other newer technology engaged in the process of catching on and becoming the norm). In places like Germany (the first real adopter of Passivhaus), the incremental cost to build Passive runs under 5% more than a traditional home built to code.
As a wholly performance-based environmentally aware building methodology, Passive House utilizes energy modeling software to accurately predict how heat and energy will behave in a given (and unique) construction scenario. The design is then honed to produce the most optimal result based on the parameters of the site, etc.
With 2020 around the corner for our Vancouver area’s target to build only carbon-neutral buildings, Passive House offers a proven platform onto which photovoltaic solutions or the like can be added in order to supplement the small amount of active energy input required to become Net-Zero or carbon-neutral. It is a no-nonsense, science-backed solution that reduces our housing footprint while creating homes and communities that are built to last.
For more information on Passive House visit the Canadian Passive House Institute West at www.canphi.ca.