Oliver Wainwright writes about Passivhaus’s fabric-first approach to energy efficiency on The Guardian, looking at how the building does the work, from super-high insulation to absolute air-tightness and harvesting the sun’s energy through windows.
It may sound – and sometimes look – like a facility for pacifying particularly violent criminals, but Passivhaus is in fact the gold standard for ultra-low energy homes, which is enjoying increasing popularity as heating bills continue to rise at astronomical rates. Developed in Germany in the early 90s by Bo Adamson and Wolfgang Feist, the Passivhaus Standard is based on a set of principles that mean homes should be able to remain at a comfortable ambient temperature of around 20C with a minimal amount of heating or cooling.
It is a “fabric-first” approach to energy efficiency, meaning the building does the work, rather than relying on bolt-on renewable energy devices, like solar panels and ground-source heat-pumps. Based on the tenets of super-high insulation, absolute air-tightness, and harvesting the sun’s energy through south-facing windows, passive houses aim to keep as much heat inside the home as possible.
They also rely on a box, usually kept in the loft: the MVHR, or mechanical ventilation heat recovery unit, a heat-exchange system that uses air from warmer rooms in the house to heat fresh air coming in.
“There are a lot of myths around Passivhaus, like you can’t open the windows and people will suffocate if the MVHR breaks down,” says Kym Mead, director of Passivhaus at the Building Research Establishment. “It’s all nonsense – you can live in it like a normal house. It’s based on the idea of harvesting the heat that comes from occupants and their devices, like TVs, computers, cookers and showers.”
The first Passivhaus homes, built in a suburb of Darmstadt in 1991, look a little like a portable classroom block, a clunky aesthetic which these ultra-low energy houses have struggled to shake off since. But standards are improving as more architects take up the challenge, and some housing associations are taking the lead, with the incentive of keeping bills down.
There are around 40,000 passive homes worldwide, with 150 in the UK, and the standard is also being applied to schools and offices – as well as an Antarctic research station.
But many remain sceptical that Passivhaus certification, which requires it to be tested by a registered inspector, is a distracting box-ticking exercise.
“Everyone wants a low-energy home, but people focus on accreditation criteria and lose sight of the bigger picture,” says architect Piers Taylor said: “It’s a one-size-fits-all approach, which can make you blind to the specifics of making each home appropriate to its context. A house should be simple, and allowed to breathe naturally.”
Original article can be viewed at: http://www.theguardian.com/artanddesign/2013/nov/01/passivhaus-fabric-first-energy-efficiency.