Does the Passive House standard make sense in cold climates?
I am a big fan of the website House Planning Help, where former radio presenter Ben Adam-Smith uses his mellifluous English radio voice to interview building experts like Bronwyn Barry and poseurs like me about green building.
In his latest interview, he talks to Martin Holladay of Green Building Advisor, asking Is the Passivhaus standard a world standard?
The Passivhaus, or Passive House standard was developed in Germany and has spread around the world. It is based on the principle that you should use enough insulation (and careful design, detailing, and use of high quality windows) so that the house or building uses less than 15 kilowatt-hours of energy per square meter of floor area per year. (see more on Passive house design here) Martin thinks that the 15kWh/m2 standard is arbitrary and silly in colder climates. He tells Ben:
By pegging an energy budget on the standard he required cold climate builders to invest an extraordinary amount of money in insulation that will never foreseeably be recovered in any possible energy savings. When true believers in the US started copying the Germans using the Central European standard in our climates they were ending up with 14 inches of rigid foam under their concrete slabs, they were ending up with R100 insulation in their attics and they were sometimes paying $6,000 or $10,000 for reducing tiny amounts of annual energy use that could easily have been supplied by a $400 solar panel producing electricity.
He goes on to suggest that what works in temperate Germany doesn't make sense in Vermont, and thinks that is justification for the Passive House US people to split off from the worldwide Passivhaus movement, so that they can "try to come up with a new Passivhaus standard that works for North American climates, which I think is a recognition that the Darmstadt, Germany, standard has no global validity."
This is not the first time Martin has made this point, (see Martin Holladay Rattles Cages with Critique of Passivhaus)
Now I live in Canada, where a blizzard is happening outside my window, and where it gets as cold or colder than Vermont or Minnesota. I don't think it is fair that I have to pay more for a winter coat to keep my body at the same temperature as somebody in Florida, but I accept the fact that for an equivalent level of comfort I need more insulation.It's the price I pay for living in a cold climate. Similarly, Passivhaus builders here are not complaining that it is too hard to achieve 15kWh/m2, they just accept that it is what happens when you live in a cold climate and you have to hit the target if you want to be a Passivhaus. Because that's what everyone else in the world is doing.
It all sounds like a bit of American Exceptionalism, " the theory that the United States is "qualitatively different" from other states." Like your winters are colder and your Kilowatts have to be BTU/hr and your fries can't be French.
There are lots of things that one can complain about in the Passivhaus world, starting with the silly and misleading name. But it was a worldwide movement of like-minded people working to a common standard, that somehow just isn't good enough for Americans or for that matter, Martin. So it instead gets confusing, with two different organizations pushing two different standards, which doesn't help anyone.
It's all a shame, because Martin makes a good point; that's a lot of foam in this photo from Martin's presentation. And in his talk with Ben, he says that he is "very much in favour of super insulation principles, especially improving the airtightness of ordinary constructions, so I think the Passivhaus movement deserves our credit for focussing on the right things."
But it was nice to think that there was a worldwide standard, a unified international movement to build better buildings. That has been lost.
Listen to the whole thing at House Planning Help.