What and where is the world’s smallest certified Passive House building? I was asked this question today and didn’t know the answer. It turns out my guess was way off.
Sustainable Engineering recently certified a New Zealand Passive House project that checks in at just 61.5m2 of Treated Floor Area (TFA). The question about the world’s smallest was asked by the client. I expected their project to be pretty close to winning that distinction.
But guess what? Colleagues at the Passive House Institute (PHI) told me the smallest certified Passive House in the PHI database is the Japanese-inspired Mizu Project in Brittany, France. It is a mere 12m2 (TFA)! and was certified in 2014. There is a great write up here [opens PDF] by the project owner about his aspirations and how he resolved the challenges inherent in such a tiny volume.
Hinoki office, the world’s smallest Passive House building. Architect, Passive House designer and building owner/occupant is Passive House engineer Thomas Primault.
It’s too small to blower door test, so an alternative testing mechanism had to be found (it clocks in at a very respectable 0.44 ACH). One of many charming touches is the cast iron Japanese kettle that was originally planned to function as the sole heating source (and a talking point, demonstrating to clients about the efficiency of Passive House buildings). However, Monday mornings could be a bit chilly after two days without making tea, so a secondary heating source was installed. It’s a delightful project and worth reading up on. It is bound to expand your notions of what is possible when it comes to small scale Passive House.
More recently, another office only a square metre larger was constructed from a shipping container. Here the conversion was done right, with outsulation. See the PHI database listing here for more details. As always, the database photos are annoyingly small and make it hard to appreciate the details. This is another architect’s studio. I note it only squeaks in on the airtightness criteria and is prone to overheating.
So contrary to my initial assumption, this small country of ours at the bottom of the world has a long way to go before we register in the Passive House tiny house (office) list.