Friday, 26 May 2017

Airtight promise

The Passivhaus, which is like a vacuum flask, conserving its heat without much need for further energy, has been marketed as the home of the future and is becoming increasingly popular across Europe. Jess McCabe travels to Hannover to meet its creator, Dr Wolfgang Feist

Dr Wolfgang Feist is darting about a construction site in the leafy outskirts of Hannover. In a few months, this will be a kindergarten filled with children, built to meet the ‘Passivhaus’ standard that Dr Feist invented. Now it is part of a tour he is leading of the city’s newest, super-insulated, airtight buildings - visiting a school, a home and this kindergarten.

Shoulders slightly hunched, a woolly hat covering his mop of grey hair, it quickly becomes clear that Dr Feist is hands-on and approachable, stepping over the uneven, unfinished floor to take pictures and inspect the site. The architects who designed the kindergarten are here, and he quickly grabs them to ask a series of pointed technical questions.

An instantly relaxing presence, he cracks jokes and tells unexpectedly gripping stories about such topics as the history of triple glazing and the effects of installing windows at an angle. Credited as an ‘energy magician’ in the German press, there’s something of the showman about him.
‘There are so many Passivhaus projects that I don’t know everyone anymore,’ he says with a grin, peeking out from under bushy eyebrows, as he ponders some of the fruits of his creation.

About 40,000 buildings around the world are certified to Passivhaus standard. But this is a recent development - almost all of them have
been erected since the turn of the century.

Getting to this stage has been a lifetime’s work for Dr Feist. It is more than 30 years since he started working on the idea of a ‘passive’ home, which could be kept warm and comfortable without much ‘active’ help from central heating.

Leading by example

The first Passivhauses were built in the early 1990s, a row of four terraced homes in Darmstadt, Germany. The idea was new and wacky. Dr Feist, his wife Witta Ebel, also a scientist at the Passivhaus

institute, and two children, moved into one of them. ‘The only way to convince others, we said, is if we ourselves will live in this building. We thought people would think, if those guys are really living in that building it can’t be too bad. It must be possible. It was a way to get it started,’ he explains.

Moving the Passivhaus from concept to a global movement took perseverance. And Dr Feist says he has had to develop patience. ‘Twenty years ago, I was angry on every building site I saw going up without decent insulation. But nowadays I just say: well, OK` it takes time,’ he says, philosophically.

This tour took place during the 16th annual Passivhaus conference, which attracted more than 1,000 people from 45 countries. Most attendees listen to the proceedings via headphones providing simultaneous translation.

Social landlords in the UK are slowly joining the Passivhaus movement, known here as passive houses. The first was only finished in 2010, a row of 10 homes in Scotland on the river Clyde.

Sustainable Housing travelled to Hannover, in northern Germany, in order to find out how the man who launched this movement came up with the idea of the Passivhaus, and whether it is finally poised to take over the mainstream.

Dr Feist is credited with inventing the Passivhaus standard, but he is insistently modest about his role in developing the homes, which have mechanical ventilation systems and require minimal heating to keep comfortable and warm.

Others who have met and worked with Dr Feist corroborate this first impression. ‘He’s very down to earth and passionate,’ says Jennifer Hardi, who works at the UK training body PassivhausUK.

‘He’s a person of the highest integrity, with a razor-sharp brain,’ says UK Passivhaus architect Justin Bere. ‘He’s blessed with an equally brilliant partner, his wife Witta, also a driving force behind the worldwide adoption of Passivhaus techniques. Between them they are succeeding where conventional politics so far failed.’

Professor Feist is clear that he is part of a bigger picture, however. ‘I just had a conversation with one of the very first guys working in that field, that’s Bernd Steinmüller. He was working in that field already in 1974. I came in later, in 1979,’ Dr Feist says diffidently, then reels off a list of the early passive building design pioneers in the US, Russia, Sweden and Denmark.

‘In the 1970s, it was already clear there were a couple of problems with energy. The world only now recognises these problems: now we are wise, now we see a problem with CO2 - but us physicists have known about the CO2 problem since the 1960s,’ he points out.

Back then, physicists such as himself (he studied solid state quantum mechanics before getting a doctorate in thermal simulations at Kassel University), began looking into the alternatives to fossil fuels. Most turned to nuclear. ‘It took most of them a long time to realise the problems of nuclear energy are not less than the problems with fossil fuels,’ Dr Feist notes.

Despite this, some researchers continued to search. ‘And then in several parts of the world, at the same time, people came up with that solution.’
To illustrate, Dr Feist picks up a flask of coffee, turning it over in his hands. ‘This vacuum bottle keeps coffee warm. And, you don’t need any energy to keep that coffee warm, so this is an intelligent technology,’ he points out, with enthusiasm. You can buy a machine to keep your coffee hot, but it needs an electric heater to achieve the same effect.

Dr Feist and the other researchers, in this coffee-pot Eureka moment, realised: ‘Most of the energy we use could be saved just by [being] a little bit more intelligent.’ And the researchers quickly realised the largest chunk of that wasted energy, 40 per cent, was being used to heat homes. ‘We said, this is so easy. You could reduce the amount of energy you need for heating the same way we do it for coffee, so that is where it started.’

Dummy run

Throughout the 1970s, researchers built demonstration houses. But, Dr Feist explains, these were ‘physical laboratories’. Nobody lived in them. Instead, they were full of equipment that simulated what it would be like if a family was cooking or living inside.

By the late 1970s, American researchers were leading the race. Jimmy Carter’s administration was generous with funding for energy efficiency and renewable technology, and great strides were made. But when Ronald Reagan came to power in 1981, he cut this funding and work ground to a halt.

Researchers in Europe, Dr Feist explains, thought hard about how to avoid the same fate. ‘So the very first houses were paid by private investors.

That is a big incentive to make it not so expensive. That was in 1991,’ Dr Feist explains, grinning. He moved into one of the first homes in 1996.

In the same year, Dr Feist founded the Passivhaus Institut, with the aim of spreading the word about the concept. The institute quickly set out standards for building and certifying Passivhauses, following up one of the first standard that was produced in 1996, based on the experiences of building those first homes.

Creator of The Passivhaus

Source: Florian Danner

Dr Wolfgang Feist chats with a developer from Hong Kong at a Passivhaus school in Hanover

At the time, the researchers thought that Passivhauses would catch on quickly. ‘For us, it was always surprising that it took such a long time. Because it’s so obvious - there are only advantages, no disadvantages,’ Dr Feist says. ‘Now Passivhauses are popping up everywhere in the world, but we are not surprised - on the contrary, we have been dissatisfied that it wasn’t happening for a long time.’

To succeed with any innovation, ‘you have to be persistent’, Dr Feist adds. ‘Some people were not able to stand it. There are also parts of industry who want to sell their products, and those products might not be good enough for a Passivhaus, so they start fighting against it.’

Dr Feist doesn’t seem to relish conflict. Last year, there was a spat in the passive house world, which ended with his institute suspending certification permission for its American counterpart, Passive House US, after it altered the standards. During the tour, two young American architects who are building a passive house approach Dr Feist to ask which standard they should use. He gives them a typical big smile, and says mildly: ‘Please do whatever is comfortable for your development. It’s totally up to you.’

Perhaps it’s possible to be philosophical because of the massive strides taken by the Passivhaus movement. This conversation is taking place in Hannover for a reason, he explains. About 30 per cent of all new buildings in the city are built to the Passivhaus standard, including those we visit on the tour.

Twenty years ago in Germany, about 180kilowatt hours of energy per square metre was needed to heat at typical new building. This has dropped to 60kWh. There’s still a long way to go before new buildings reach the Passivhaus standard of 15kWh, but there has been progress, Dr Feist argues. ‘In the 1990s, we discussed a 60kWh standard, and people said, oh that’s nonsense, far too expensive. And now it’s just what everybody does.’

The new normal

He adds, ‘I think in 10 years, that’s 2022, all the things we are discussing now: triple glazing, airtight window frames, airtight construction, good insulation, ventilation with heat recovery. All these things will be just normal, just what you do.’ The standards set by the Passivhaus Institut, currently seen as stringently high, will become as normal as the flushing toilet, he predicts. ‘In 10 years, I don’t know if anybody will talk about Passivhaus.’

The institute has ambitious targets. At present, there are 20 million square metres of Passivhaus buildings. By 2021, they expect this to increase to 500 milllion square metres.

And in the UK, which he has visited numerous times, Dr Feist says, gesticulating, Passivhaus should be an easy sell. Most homes are ‘extraordinarily uncomfortable. It’s cold, it’s drafty, it’s even humid during winter. We would ask ourselves, “why do you stay in such conditions”.’

When asked if people need to change their lifestyle when they move into a Passivhaus, Dr Feist interrupts, passionately: ‘No, I don’t agree.’

In the Austrian university town of Innsbruck - where Dr Feist has been a professor of building physics since 2008 - the local social housing organisation has built a Passivhaus block of 235 flats. ‘This is a group of tenants - lots of them don’t speak German, so the social housing organisation of Tyrolia [an Austrian state] said it has to be self-explanatory. We design the building to fit the people. We don’t design the people to fit the building. This is the philosophy of the Passivhaus,’ Dr Feist insists.

Whether or not this works in practice is another matter. One of the stops on our tour is a 1900s house, converted into apartments and offices. The Schmidt family live in the main flat. During the tour, the youngest son wanders into the kitchen in shorts and bare feet. A lot of the heat comes in the form of passive solar energy through a giant sloping window. The boy’s grandmother lives in another flat. ‘She’s 85 years old, she doesn’t understand,’ Mrs Schmidt explains. She doesn’t let enough sun into her apartment and complains of being too cold.

This practical example seems to bely Dr Feist’s insistence that Passivhauses don’t need an instruction manual.

He also insists that building to Passivhaus standards shouldn’t be extortionately expensive. The Tyrolian social housing project, for example, cost just 4.5 per cent more than a standard construction.

‘There are some learning costs. If a company has never built a Passivhaus, and builds its first one, they won’t be successful with 4.5 per cent,’ he says, getting out his pencil and paper and drawing graphs to explain his point. Those first four Passivhauses, back in the 1990s, cost a premium of 19 per cent. A developer building their first Passivhaus now should expect extra costs of about 10 to 12 per cent.

Dr Feist is far from complacent about the pace of change. He has been watching the UK government shift the definition of a ‘zero carbon home’ with obvious irritation.

‘That’s a national British discussion, but we have similar things happening in Germany - there’s a lot of greenwash going on,’ he says.

Quest for zero

‘I’m a physicist, so zero is something special. Zero is zero. Zero is not five, it’s not one, it’s not 0.5 and it’s not 0.000001. So if you talk about zero, and then you define 42 to be zero, that’s scientific nonsense. I would strictly recommend that you don’t talk too much about zero. He writes the word ‘zero’ on a piece of paper in pencil, underlines it, and then circles it.

He points out his standard is called Passivhaus, not zero energy house. ‘We want to be honest about what we do.’

Dr Feist doesn’t seem to be able to take a pessimistic view even about this linguistic betrayal of scientific accuracy, however. ‘Twenty years ago people were completely ignoring it and saying it was nonsense. Now they at least do greenwash,’ he says, chortling.

And the flipside, he adds, is that the world doesn’t need to reduce the energy from homes to zero. ‘Almost zero is good enough,’ he says. ‘If you want to go to zero, it’s expensive, it’s difficult, it’s almost not possible.’

The average American or European man, he says, is constantly consuming about 5,000 watts of energy. The world’s population will soon reach 9 billion, and there’s not enough resources for every person to reach this level of consumption. To be truly sustainable, humans can consume about a fifth of this level. ‘That might sound like bad news, but the good news is that we can handle that.’

Passivhauses cut energy use by a factor of 10. So by 2050, the average building - new and old - needs to be about half as efficient as a Passivhaus. This means new buildings will have to be very efficient, and most old buildings will have to be retrofitted to much higher standards.

And there will have to be enough wiggle room for exceptions, says Dr Feist. ‘Like London’s Houses of Parliament - you don’t want to insulate that one from the outside!’

For more on the Passivhaus standard, visit

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