Our editor-at-large outlines why building to Passivhaus standard is an aspiration worth aiming for
Image: As featured on Grand Designs in 2014, Periscope House attained Code 6 – a now defunct British standard similar to Passivhaus. Photographer: Darren chung
Kevin McCloud highlights the reasons for building Passivhaus above all other self build methods.
The insulation is next to none
"Passivhaus houses are super insulated like polar bears. They are built to very high levels of airtightness to keep the warm air in and avoid draughts, like a space capsule.
They are designed with mechanical ventilation with heat recovery (MVHR) to recycle the heat in the building and provide tons of filtered, warmed super-fresh air to keep you healthy, just like a brisk summer’s walk in the Malvern Hills.
What they are not is chilly, expensive to heat, draughty, stuffy and running with condensation – qualities we proudly and defiantly like to associate with the average British home."
UK is behind the times
"Our equivalent of MVHR is to put trickle vents in windows that mimic the draughts produced by poorly made, badly fitted windows in the 14th century. Passivhaus houses are, of course, foreign, built by people who can’t understand why 21st-century British house builders haven’t moved on from their medieval forebears.
The apocryphal story goes that when Yvette Cooper was housing minister in the last Labour Government, she visited a Swedish Passivhaus project in the depths of winter. Snow and ice lay all around and the temperature would not budge above -15°C. She asked an elderly couple how on earth they managed to stay warm in a house without central or underfloor heating – just an MVHR unit – and they replied that every human radiates about one kilowatt of energy, which they thought might be enough to heat their home.
In the darkest, coldest months, however, it had got a bit too chilly for them: “Then we got a dog,” they added. The third heat source obviously solved the problem."
MVHR vs boilers
"I have visited so many contemporary British homes where the owners, building to high levels of airtightness and insulation, bottled at the last minute and supplemented their MVHR unit with a boiler, only to discover they never used it. In the UK, we are suspicious of any building technology that claims to deliver near-zero bills, and addicted to the idea of fossil-fuel backup, despite the fact our climate seems to be warming and our winters are nowhere near polar.
We also suspect that in summer you’re not allowed to open the windows in a Passivhaus home, which is rubbish."
Don't be scared of the upfront costs
"I’ve also visited self-built British homes that are really well constructed and cosy where the owners have pulled back from a Passiv level of insulation and airtightness and delayed the solar panels because they wanted to save money – which is bonkers when you think about it. Would you rather save £20,000 on your three-bedroom project only to face annual energy bills of more than £1,000? If you asked a business owner if they’d rather limit the value of their company and take a hit on their annual turnover, they’d laugh. They know that saving money every year generates profit, which increases the value of their capital asset.
So it is with our homes. These days, the greener your home, the more attractive it will be to potential buyers and the sooner you’ll sell it."
UK Passivhaus shortage
"We broadcast the building of England’s first Passivhaus home – the earth-sheltered concrete property of the architect Helen Seymour Smith – in 2010 and today, in 2019, the total number of certified Passivhaus homes in England stands at a lowly 81. There are, by contrast, 2,353 in Germany and 4,599 worldwide; numbers which put us to shame.
Many of the homes we film are built to Passivhaus standards but are not taken through the assessment process. In 2014, we showed Natasha Cargill’s Periscope House in Norfolk, designed by Studio Bark, which followed this path, but which did achieve the British equivalent, Code Level 6 accreditation, the highest available.
I should add at this point that this Government has since scrapped the eco-building Codes along with all targets for zero carbon in construction following extensive lobbying by the house-building industry. Another badge of shame for Britain, another reason why we are the laughing stock of Europe."
Let's set the example now
"So we need self-builders, more than ever, to pick up the mantle of Passivhaus construction and set the example. Whether you decide to go for full accreditation with the Passivhaus institute, or whether you build to a now-fictitious Code level, or whether you just try to make your house as energy efficient and airtight as you can, look at the example that Passivhaus buildings set.
At the very least, don’t just stick a gas boiler in your home, but buy another jumper. And maybe get a dog."
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