We, and I imagine most Passivhaus Designers, spend a certain amount of time battling ‘Passivhaus Myths’. These are lots of misconceptions and misunderstandings that have arisen, but like a bad zombie movie, refuse to die and keep coming back, no matter how much we patiently explain them away.
Some of the most common myths we hear are:
“Passivhauses are ugly”
“The air in Passivhauses is too dry”
“You have to live differently in a Passivhaus”
and possibly the most pervasive:
“You can’t open the windows in a Passivhaus”
There are plenty more of course. This article was inspired by a strange comment in the Guardian article covering Goldsmith Street for which we provided M&E design services in collaboration with Warm. The article mentioned that “Passivhaus means windows have to be raised up around half a metre from the ground”. This is not correct; although it is often a good idea to set window sills at a certain height, there’s nothing explicitly within the standard that specifies window sill heights.
One of the great things about Passivhaus is that it’s a descriptive, rather than a prescriptive standard. It sets out the fewest possible constraints to achieve its objectives, and allows designers free rein to meet those transparent and science-based criteria.
This article suddenly galvanised a thought which had been milling around my sub-conscious for some time, a simple test for busting Passivhaus myths. It goes like this:
Take any statement you think might be a Passivhaus myth, and replace the word Passivhaus with the phrase “very energy efficient building”. If it sounds silly, congratulations! You have busted a myth. If it sounds perfectly sensible, also congratulations! You have made a valid observation about not just Passivhauses, but all very energy efficient buildings, and maybe even all buildings.
So the examples above become:
“Very Energy Efficient Buildings are ugly”.
Sounds silly. It’s a myth.
“The air in Very Energy Efficient Buildings is too dry”.
“You have to live differently in a Very Energy Efficient Building”
“You can’t open the windows in a Very Energy Efficient Building”.
A variation on the last example of my own concoction:
“If you leave the windows in a Passivhaus open all winter, it will be uncomfortable and wasteful of heating energy”
“If you leave the windows in a Very Energy Efficient Building open all winter, it will be uncomfortable and wasteful of heating energy”
Both of these statements make perfect sense, and would also apply to all buildings irrespective of their design energy efficiency. This is therefore not a myth, but simply a statement that is correct for pretty much all buildings. So, of course you can open the windows in a Passivhaus, we’d positively encourage it, but don’t be surprised if your bills are a bit high if you leave them open all the time and turn your thermostat up to 27°C…
So next time you hear someone claim something strange about Passivhaus that might be a myth, apply our handy test. We’d love to hear any Passivhaus myths you’ve busted, so do send us your ‘favourite’ examples!