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Passivhaus – gathers steam in UK, halters in US

by Mel Starrs on September 7, 2011

in Passivhaus

Passivhaus. I have a love/hate relationship with the standard. What really intrigues me is how as a standard it has captured the imagination of the industry in a way that CSH, for example, has completely failed to do? Why is this? Is it Wolfgang Feist, the public face of the standard who is typically characterised as delightfully ‘mad scientist’ in his demeanour? Or is it the simpleness of the standard?

I see it’s virtues but for some bizarre reason it tends to generate a zealousness not seen elsewhere, and this generally serves to put me off, making me suspicious and looking for faults. My biggest complaint? It’s just a spreadsheet (PHPP) with a doable but stretching target. It is nothing more than this. Building services engineers (especially before SBEM) used similar spreadsheets for years with no wild claims of solving all the planet’s energy efficiency ills.

However, I’ve had an interest in Passivhaus from the early days of the blog. I have worked on a few schemes (none of which made it past pre-planning – mostly for budget reasons), and I know via Twitter and real life a growing, tight group of fans and practicioners who are making a decent living out of being experts in Passivhaus.

Given my retiscence of embracing the standard in the true fervour most proponents of it seem to have done, I am really looking forward to the CIBSE EPG debate on 22 September:

Passivhaus buildings claim to provide a high level of occupant comfort while using very little energy for heating and cooling. They are supposed to be built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany. However, is this a myth or a reality?

Passivhaus has developed a large and growing body of support among those interested in creating sustainable architecture, but some architects and engineers question how appropriate/practical the standard is. Is Passivhaus the ideal model for sustainable buildings? Does it target the right things? Is it practical? Are the buildings comfortable? Has Passivhaus helped or hindered?

Expert speakers include Mark Elton (ECD Architects), Nick Grant (UK Passivhaus Trust) and Liz Reason (Reasons to be Cheerful Ltd). This will be a FOR and AGAINST debate with audience participation through Q&A, hopefully leading to an enjoyable evening and some clarity on the subject.

AECB have been supporters of the standard for years, currently trying to get it integrated into Building Regulations more successfully – for more detail see Neil’s blog on ‘deemed to satisfy’ here. They might be on to a winner there as BRE are now  currently pushing Passivhaus quite agressively too. I wonder what will happen when the two cultures meet though – in my eyes, AECB being a radically different beast to BRE.

From all this current interest in the UK, perhaps a cautionary take from the US. This story broke over the summer and has turned into a bit of a palaver.

Passivhaus has had to date a mixed reception in the US – the majority of comment I have seen prior to the latest episode came from Martin Holladay, a very hands on expert (think a US Mark Brinkley). Martin Holladay has had reservations with regards to Passivhaus for some time, branding the targets arbitrary but also heaping praise on the practicioners of the standard.

Then, a couple of weeks ago, the Passivhaus Institut, founded by Dr. Wolfgang Feist in 1996, revoked certifier status held by Passive House US (PHIUS), the only Passive House certifier in the United States (see Jetson Green article).

In the UK there are currently 3 companies/bodies who can certify – BRE, Peter Warm (an AECB member) (Passivhaus only) and Inbuilt (my ex-employer – doing Passivhaus and EnerPHit). Peter’s website is a great resource of all things Passivhaus including a map of the 11 certified buildings in the UK. Yes, there are only 11 certified buildings so far, but with the nation’s obsession for certificates (I recented had it pointed out on Twitter that this might come from being a nation of badge winning scouts and brownies!?) and the BRE’s involvement, I assume they are hoping this will grow exponentially.

Anyway, if you want a building certifed you go through one of the approved companies (and it would make sense to go for a local presence), and until the falling out PHIUS was one such body. Buildings in the States can still get certified, but could use one of the 3 UK companies or any of the others on the list. So the loss of PHIUS isn’t really that much of a big deal. What is of more interest is the resaons why the falling out happened. Preston covers three reasons on his blog:

First, PHIUS allegedly certified Passive House buildings without the requisite documentation, threatening the integrity of the standard.  …

Second, PHIUS allegedly infringed the Passivhaus Institut’s copyright in the PHPP software by selling and making changes to it without authorization or license.

Third, PHIUS introduced a competing professional certification scheme and allegedly refused to honor existing contractual obligations with the Passivhaus Institut.

Inhabitat says the expulsion “…also reflects the commitment the Passivhaus Institute has to the quality of its certification process.” Wolfgang Feist’s two letters can be read here and the response from PHIUS is linked to from here (lots more links to other blogs on the acrimony there too if you want to read more). From the PHIUS response:

  • The Passivhaus Institut (PHI) in Germany has made “often-capricious, bureaucratic and cumbersome demands.”
  • The Passivhaus Standard “belongs to no one or no organization.”
  • “Dr. Feist and PHI long ago lost control of the European certification process and with it lost its legitimacy on this issue.”

These are points worth making – of the quoted 20,000 Passivhaus‘s in Europe only a proportion have bothered with certification (This document implies 32,000 certified, of 46,000 in total?). To a UK mind (and indeed a US one) this is boggling – how can they possibly know they are correct without a piece of paper? Then again, can anyone claim owenership over what is to all intents and purposes (as I said above) a spreadsheet with a doable but stretching target?

PHI seem to have taken control of the situation and are trying to make sure that only ‘properly’ certified buildings can be called Passivhaus. Probably a good move but I’ll be interested to see how the UK box ticking culture (cultivated from CSH – sorry to bash it yet again) plays out against our demand for certificates. If AECB successfully push Passivhaus into the Building Regs, is the UK ready for the stringent paperwork and evidence involved? Will we see planners start to impose it as a standard in the same way CSH has been? The BRE obviously feel the standard is valuable in the UK marketplace.

Whilst I would love to do the CEPH qualification (I do love collecting those letters after my name – good little girl guide that I am), I’m not sure the demand justifies me doing so yet. Any thoughts from already qualified CEPH’ers?

  • Alan

    Mel, I suggest you dip your toe in the water with just a couple of days of PHPP course – I went on Pete Warm’s one, and in entirely biased fashion, commend it to you. 
    As a fellow energy nerd I think you’ll like PHPP – the choice of implementation in Excel doesn’t detract from the rigour or quality of the model, it could just as well be coded behind a flashy front end, but as a spreadsheet the algorithms are all accessible for the user to look at if they want (unlike, say, SBEM). Also, not being a full dynamic model, you can play with the specification of a building and get an instant energy result, rather than waiting for the simulation to grind through a year’s data – and get more of a feel for how simple things like built form, or orientation, affect heating demand in a low energy building.


  • Linn Rafferty

    Very interesting about the user altering the standard without refering back to the ‘owner’.  Reminds me a bit of early BREDEM development – again, who was the real owner? the theoretical owner who was credited with writing it, or its users who were in touch with the practical issues?
    Similar issues about certification also arose in early BREDEM days; 100s of 1000s of properties given ‘SAP’ ratings although no more than a couple of 1000 were ever certificated. A subject in itself, perhaps!

  • Elrond Burrell

    We love Passivhaus because
    – it is about the design of the building – CSH / BREEAM isn’t- the spreadsheet (PHPP) is a design tool and used interactively during the design process, not a pointless bureaucratic tickbox exercise decoupled from the design process
    – the built results are as good as or better than predicted, the opposite being true of BREEAM / CSH / LEED
    – it is clear about it’s purpose: energy reduction & indoor comfort, and it achieves these, the actual purpose of CSH etc is not clear, nor if it achieves it (What exactly is a “Sustainable home”, one with a cash point nearby?)
    – it is an independent standard, NOT an “industry lead” standard (Spot the industries influence on CSH? PVC is an A-rated green material? BRE conflict of interest perhaps?)
    – it is about the design of the building, did I mention that already!
    – it is a PERFORMANCE standard not a prescriptive list of requirements
    – it genuinely reduces energy use/waste, there is no “off-setting” involved

    I’m sure there is more to add but that’ll do for now! 🙂

  • Nick

    Also recommend dipping your toe. No it isnt magic but the devil is in the detail. Like Alan Im much happier being sceptical but do find I spend a lot of time correcting misconceptions including about the limitations of PHPP being a simple degree day model. Alan is teaching the serviced module in a weeks time and I’ll be sitting in on it, great if you had the time to do it!


  • Alan

    To add to my first comment, the PHPP model isn’t all there is to Passivhaus of course. The real USP is the fact that it delivers on measured performance. Of course real building energy use is notoriously hard to predict, users, weather, etc etc – but you can in fact measure the actual heat loss of a building by treating it as a house-sized hot box in so-called co-heating tests. These measure actual heat loss, and often show up large discrepancies between design expectation and reality, eg
    Passivhaus originated from a thought that buildings ought not to be exempt from the laws of physics, and the heat loss ought to be calculable if you take enough care to include everything that is significant. 
    So far, and admittedly looking at some carefully supervised first Passivhaus projects, the co-heating results look very good. We shouldn’t be too surprised – the theory of heat transfer is well understood. All Passivhaus does is first insist that we do our sums properly, work out real timber frame fractions, use realistic insulation properties, use actual window frame dimensions rather than a “typical” glazed percentage, including totals for length of glazing spacer, account for all thermal bridges including tricky situations where window frame meets wall for instance and so on.  Of course some details will turn out to be a terrible idea when the thermal bridges are modelled in detail, and we spend some time coming up with better ones.
    Then Passivhaus insists we build accurately to the design – not that hard you’d think – but does require more detail design than builders may be used to seeing, and greater insistence that they actually follow the design.  
    The end result is that when heating energy use is measured in finished houses, it turns out PHPP makes a good prediction. You are not likely to get the standard 15kWh/2.a in every house, or any at all for that matter – individual usage varies such a lot, and the effect is amplified when the residual heat demand is as low as this – but when averaged over whole estates of Passivhaus dwellings show the standard does deliver.

  • Nickdevlin

    Mel, Both Alan and Nick’s comments are on the money. I think the biggest advantage is that the complexity of identifying and accounting for all the heat loss helps the whole design team to understand the issues of good design / detailling much better. One comment about the Building Regs aspect you mention above – I believe the intention of the ‘deemed to comply’ approach is not necessarily to encourage more submissions to BCO (I think you’re right, the industry isnt fully ready for more paperwork) but rather just to have those that have already committed to the process and standard have it recognised with no need to replicate the work with a SAP calc. 

    Come on over to the darkside…

    Alan / Nick – if you need any more independent eyes for Alan’s teaching, let me know.. 

  • Juraj Mikurcik

    I’ve done the CEPH course at Warm’s earlier this year and it has been an excellent experience. Whilst the full course might be a bit too much for someone wanting to know what it’s all about, I too would recommend a one/ two day introductory minicourse. Essentially PH is all about designing REAL low energy buildings from the first principles. What I enjoyed most at the course were not the PHPP spreadsheets (tho this is a vital tool), but the sheer enthusiasm for understanding basic building physics, which ultimately results in better buildings. If everyone in the building industry had just a basic understanding of building physics (including polititians that make building law), the discussion would be on a completely different level. I think it’s all about real life performance – you should deliver what you promise. And PH provides a pretty good platform to deliver that promise.

  • Martin

    A couple of minor points of fact – SPHC is a fourth certifying body in the UK; and of the 11 certified “buildings” one is a terrace of 10 houses. I know that doesn’t change the overall picture, but these things get quoted and re-quoted.

    As a client going through the process of developing a PH, my observation is that there are indeed a number of uncertified “Passive Houses” around. Some of them at least are known as PH as a shorthand, I think, to avoid the owners having to explain the rather more complicated “designed and built broadly in line with PH principles, but with a few corners cut where I thought it didn’t matter”. The difficulty with this approach is that, without doing the sums and getting the certificate, it’s difficult to know what sort of heating system to install. As other commenters have pointed out, PHPP has a pretty good record of predicting energy use, and the normal alternative (plumber’s gut feel, generally with a high margin for error because no-one wants to be called back by a client because they’re freezing) just doesn’t work for low-energy houses. So it’s easy to dismiss PH certification as a reflection of the girl guide/ boy scout mentality, but to my mind it adds value.

  • GM’A

    Hi Mel; Sorry to miss your talk in Yorkshire (W).  I am an ex-NHER Assessor based in Yorkshire (S) and I recently reconnected to the AECB practitioners; mainly to see if I was too out-of-date to get into PH work.  I have had a long detour through Supported Housing development and Regional (Commercial) Development; where the need for comprehensible standards seemed to be even more urgent.  In that context I came to the conclusion that the only good Certificate was a completed Display Energy Certificate (DEC, and report).  I was, professionally, relieved (and I supposed ‘politically’ surprised/ disappointed) how little has changed in the housing aspects of assessment and evaluation in the domestic design process.  AECB can come acroos as a ‘Porche Owners Club’ for PH owners-builders; but at least they are doing something that can be monitored.  I failed to persuede the TSB to target existing constructed high-quality building stock for re-assessment; they seeemed not so keen to know that an RSL had in 1997 an Average NHER of 7ish across it’s whole stock – with several units air-tightness Certified (which seems, to me, to be the key functional component of the PH ‘certification’ concept.