This time last year I was standing on a beach in Cuba watching my two long-time friends, Reed & Aneesa, get united in marriage. This year I stood with them on an overgrown lot in the Hillside/Quadra area watching a derelict abandoned building get pulled to the ground and hauled off in dusty pieces. Though the scenery differs significantly, this is just the next step on their journey together.
Early on it was decided that it was important that the build process reflect their deeply held personal values regarding environmental protection. In the end they settled on the Passive House model. In upcoming Blog posts, I hope to have them write some guest spots on their perspective and their continuing experience as we move from design through construction.
What is a Passive House? It’s a common question with a lot of misleading information available. In layman’s terms, a Passive House has a highly efficient and controlled interior environment that dramatically reduces the homes energy consumption, and increases comfort and health for the inhabitants. For a more technical definition, try the Passipedia definition.
How do we achieve this and how is it measured? The entire building must be designed with the Passive House modelling software (PHPP) from the ground up. Site location and building orientation play crucial roles in making this possible. The passive solar gain, through precisely placed windows, provides the majority of the heat for the building. Carefully calculated overhangs and window location and size control overheating in the summer months. The building must be air-tight to stop all unconditioned air from infiltrating the building envelope, with the interior fresh air exchanges controlled by an HRV unit. Additional insulation and special high-efficiency windows are required to slow heat loss. Thermal bridging of every structural component is calculated and detailed to reduce energy transfer.
Nearly every other facet of our world has seen wide and often staggering scientific improvements that generally enhance our lives. But we still tend to build houses with the same thermal, air quality, and energy considerations that we did before the transistor radio came along. And no I’m not exaggerating – insulation got 2” thicker, we’ve adopted some rudimentary air and moisture control barriers, and that’s about it. Many early systems received bad publicity due to some cases causing rot or poor interior air quality. The fault typically lay with improper design, application, or combinations of incompatible systems used by builders – the science was sound, and it continues to improve.
Stay tuned in upcoming months as we cover the unique assemblies and materials we’ll be using to accomplish this task. Hopefully the free sharing of information will make it easier for other builders to adopt Passive House systems and for everyone to see how a few small changes can make one huge difference. We invite both homeowners and builders alike to join us on Reed & Aneesa’s Passive House journey.
Technical Side-Bar
In our Passive House plan, the air-barrier is found at the outside sheathing plane where I firmly believe it belongs. Weather and vapour barriers will be found in their traditional locations. 6” of exterior insulation will be applied outside the framed walls, in part to remove the excess of thermal bridging that occurs through studs and wall plates. We will be applying strapping for our rain-screen drainage plane outside the insulation layer and then cladding the building like any other.