21 Nov 2008

Wolfgang Feist, Mr Passivhaus

I joined a throng of about 250 people gathered last night in central London to hear a 40 minute lecture by Wolfgang Feist, Mr Passivhaus. In the obscurantist world of energy efficient building design, Feist is the nearest thing you will get to a superstar and this was the first time he had spoken in public in the UK. He spoke in excellent English and held the stage with his presentation, although in truth, for those who already know about the Passivhaus movement, there wasn’t anything particularly new to be gleaned. In any event, he was preaching to the converted, although in the bar afterwards it was suggested to me that I wasn’t wholly on board. Oh dear, what is it with me?

A few snippets I did glean. Feist and his family actually live in the oft-photographed original Passivhaus terrace built in Darmstadt in 1991. This is where the story started. His average energy consumption for space heating in this house is just 9kWh/m2/a; the Passivhaus standard is 15kWh/m2/a. In fact he showed a fascinating slide showing that though 15kWh/m2/a is the hoped for energy consumption in a Passivhaus, the range of outcomes measured at 32 Passivhauses on an estate in Hanover was between 4kWh/m2/a and 25kWh/m2/a. “if people like to keep the internal room temepartures at 25°C, then the energy use is going to be high. But then it’s still going to be much lower than on conventional homes.” He showed that such a range of outcomes was fairly typical across any group of homes studied.

He also said he was proud of the fact that were now over 40 Passiv Schools in Germany: schools of course help to disseminate the principles of low energy design because they are used by so many people.

Finally, he invited everyone to the next PassivHaus annual conference in Frankfurt in April 17/18 next year.

The talk was put on by the AECB, who also used the spot to promote their CarbonLite standard which is closely based on PassivHaus principles. What wasn’t explained was why the AECB should be supporting a different standard. Perhaps it will all become clearer to me in time.


  1. That’s a nice piece of writing. Like you, I have wondered why AECB has chosen to adopt a different name and slightly different standard. I understand the AECB now have a licence from the Passivhaus Institute to grant Passivhaus certification and in the interest of clarity, I cannot see why anyone would want to continue with a different name.

  2. I attended an AECB training course recently that covered passivhaus and although I found it informative and quite good, I also found it totally lacking in real technical detail, both about the subject itself and also how to implement it.

    Although I think passivhaus is a great standard for building fabric, from what I understand, It doesn't account for where those few Kw's that are required for heating come from. You could use electric heating for instance, and would not be penalised, but we all know that electricaly is about 10 - 11 times more carbon intensive than mains gas.

    Although flawed, I understand why CSH was adopted. It covers not only just the building fabric, but tries to help inflence peoples habits, like home office space and bike stores.

    Personally I think we should just put all our effort and money into coming up with zero carbon electricity for the masses. It is ultimately what we will have to do anyway, and once it happens can make the existing housing stock green by default!


  3. Hi Mark

    Was good to chat at the bar but was It my innocent question 'have you warmed to Passivhaus?' that you interpreted as a challenge of faith??

    A few points mostly relating to the other comments.

    As I understand it (I am an AECB Board member but not part of the CLP work) the AECB standards are based on the PH methodology but are adapted to the UK situation (not climate as PH is for all climates).

    The Carbon Lite Program website explains it better than I can, but the idea is to offer Silver as a step to Passivhaus, more easily achieved with standard construction and sub PH windows etc. Step 2 of CLP is PH but with carbon emissions taken into account.

    PH considers the fact that electricity is more (about 3 not 10-11 times) carbon intensive as gas by calculating primary energy. This is the German way hence the AECB version looks at Carbon. However both approaches start by designing for low energy not low carbon. This ensures that the fabric is done right. Rather than relying on wood (not enough to go round) or a biodiesel fuelled Aga as some do.

    Now there’s a candidate for an eco-Bollocks award.

    Please feel free to discuss on the AECB forum where critical thought is always welcome and where there are plenty of practical details for meeting PH and AECB energy standards plus discussion of materials, water etc.




  4. Nick

    It was the AECB corse I attended that stated that Leccy was 11 times more carbon intensive than mains gas.

    Any further information, however, would be greatfully recieved.


  5. Lewis,

    There is debate about just how much more carbon intensive electricity is than mains gas or oil. As its supplied over a grid, which has varying efficiency itself, from a variety of sources, each with their own mix of fuels, it's not an easy call, and it almost certainly varies through the day and through the year. The official figure is that it is 2.5 times more carbon intensive than gas, but this is widely disputed by many sources, who suggest its more likely to be 3 to 5 times more. But 11 times? That does seem a tad excessive.

    Yes it was your googly that I was referring to. My doubts about Passivhaus have been aired on my blog over the past two years and I don't want to revive them now, as they are in fact fairly minor - more just observations really.

  6. Mark,

    Ok thanks, I must have got my wires crossed somewhere on that one!

    I know for CSH, N0x emission for electric heating is about 17x that of a class 5 boiler (1200 vs 70), but is that accurate, or a weighting added to ensure that we are diverted away from electric heating?



  7. Lewis,

    I've no idea. At the moment, Part L discriminates in favour of electric heating by giving electricity a very soft score, known as the Fuel Factor Fudge. Another bit of info I gleaned from the Wolfang Feist event was that the next revision of Part L is likely to address this anomaly. No more fudging. But if the actual carbon intensity of electricity is so controversial, it seems difficult to come to a sensible conclusion on this one. A lot of Passivhauses in Germany have all-electric heating.

  8. The primary energy Passivhaus criteria of max. 120kWh/m2 a does cover the source of of the energy. Most Passivhauses in Germany are heated with so called "compact systems": a combination of a air-air-heat exchanger and a heat pump which operates with a COP of about 3. Few use direct electric heat and still meet the Primary Energy criteria.

  9. Hey,

    I'm working on a thesis which compares the Passivhaus program in Germany, where it's quite succesful, and the Netherlands, where it isn't implemented as such. At the moment I'm trying to gather as much information as possible and most information I can find describes the technological specifications, but I'm having a hard time finding anything about the policy surrounding PH. Do you know any sites where the implementation policies are described in further detail? It would greatly further my research.

    Dick de Munter

  10. Dick,

    I can't help you. All I know is that Passivhaus builders has received support from local authorities and or mortgage providers in Germany and Austria. Just what the terms are, I don't know.