Monte Paulsen, a passive house specialist with Vancouver-based RDH Building Science was the speaker for the "Passive House 2.0" session at the Wood Design and Construction Solutions Conference held on Feb 28. In Vancouver.
Paulsen said solar powered "spaceship" houses are often mistaken for passive house projects, but are in fact heat leaking structures that are "everything we hate." Passive house can be and is commercial towers and mid-rise buildings. The missing component, he said, is housing, but progress is being made.
The lion's share of energy in a typical Vancouver house goes to heating, Paulsen said, and what passive house does is "put a sweater around the whole building."
Triple glazing, making the house thermal bridge-free, airtightness and mechanical ventilation are the cornerstones of passive house, he said.
Core values are a limit on heat demand, making the primary energy renewable, making sure the building is airtight, and reducing the frequency of overheating.
Paulsen also stressed that a passive house still uses mechanical and electrical systems, but is designed in such a way that in spring and fall there is no need for those systems, allowing use in winter and summer while still saving energy.
Passive house not achievable without the PHPP energy modeling tool, but it also is not a green standard per se.
Passive house is growing in Vancouver because "things happen once government counts carbon," Paulsen said.
Electricity rates are highly subsidized in B.C., Paulsen said, and no-one is thinking about energy savings because of that subsidization. But the government is counting carbon, and greenhouse gas (GHG) emmissions can be substantially cut from buildings, most fo which are located in high population areas such as Vancouver.
But Gas furnaces and gas boilers, which are in most Vancouver single family homes, also generate GHGs. A passive house does not have that boiler system, so it can't produce the GHGs. The building simply can't burn the fossil fuels, which reduces emissions. Passive house, Paulsen said, is the cheapest way to cut GHGs.
"Passive house is a team sport," Paulsen said, and B.C. was introduced to the concept during the 2010 Olympics when the Austrians left the Lost Lake Passive House (the first in Canada) behind once the Olympics concluded. BC Passive House then created luxury homes in Whistler using Passive House methods. B.C. is now exporting passive house components to Europe.
Passive House requires a level of detail that demands extensive planning and schematics before construction begins. Design stage review is unique to passive house, a step where a building certifier ensures the designs are acceptable before design development begins. Ventilation is commissioned and extensive airtightness testing is part of the construction process.
Another lesson of passive house design is that "simple shapes cost less," Paulsen said. Shape matters because a cube, for example has a large surface-to-floor ratio, but once multiple floors are introduced, that ratio is reduced.
Vancouver's approach to passive house is somewhat like its approach to laneway housing; tentative at first, Paulsen said, but evolving and accelerating.
Passive House, he added, is NOT about solar, it is instead about balancing internal gains with losses, which isn't necessarily a function of solar energy. Some passive houses have no windows at all, Paulsen said. Smart shading can also do the work of accessing solar when needed. Overheating, which can happen with solar energy, is the biggest challenge to overcome. Wall assemblies are also important, he said, and thinner walls can also be cost-efficient.
Modular passive house, Paulsen said, lets remote communities add to their housing stock without having to draw upon often scarce energy resources.
"It completely changes the game," he said.
Passive house certification is a feasible goal, he said, but current homes are losing energy through thermal bridges in foundations in single family homes and concrete balconies on multi-residential buildings.
"Eliminating exposed slab edges is critical to affordability," he said. Even non passive house projects will have to examine this practice, Paulsen said, because concrete causes much more of a thermal bridge than wood.