I have just returned from the UK Passivhaus Conference 2012, held in Nottingham. Two days of lectures, networking, eating, drinking and schmoozing in East Midlands Conference Centre and a night sleeping in the brand new Orchard Hotel next door, so new that it wasn't actually finished.
As is so often the case with events like this, you come back down slowly to earth with a huge swathe of unnoticed feelings and unformed opinions, and only gradually do you assimilate the drift of what was going on there.
Some obvious things stand out: Passivhaus is a success if measured by the number of projects underway in this country (75 underway or completed, up from very little last year), and the spread of people taking an interest has widened to include lots of businesses I had never heard of before. There is a surprising amount of interest from RSLs who are more concerned with whole-life costings than up front capital costs, and see a genuine payback in using Passivhaus principles if measuring over a 25 year period. Many of these 75 schemes involve several units: they are not all one-offs.
And there is also great interest from the schools sector and one or two offices. I also talked to a man who was sussing out whether Passivhaus would be suitable for a fire station.
If there was a theme this year, it was summed up by the number of presentations, especially on Day Two, on Post Occupancy Testing. Lots of figures, lots of graphs and lots of tables, all rather hard to take in slide shows if truth be told, but with one over-arching theme — Passivhaus delivers what it says on the tin. Whereas the building world has been bedevilled by many so-called green projects which turned out to be anything but, Passivhaus standards, if properly instigated, seem to hit their targets unerringly.
But, you might argue, we knew that already. Well, yes it's true: there have been lots of testing carried out in Germany and Austria and the reason that Passivhaus is catching on elsewhere is that it has been proven to be effective. Post Completion Testing is construction's equivalent of the Double Blind Trial — a little bit of scientific rigour brought to bear.
What's interesting about this is that it puts Passivhaus firmly into the enlightenment camp of people who believe in logic and science and physics in particular. Not all green construction resides here and there were many people there uneasy about some of the reductive nature of Passivhaus. If Passivhaus works, does it follow that we should be building compact, rectangular boxes, all clad in white render in a vaguely international style? Does engineering have to trump aesthetics every time? And what about if you want to build using more cuddly materials like straw bale, or turf roofs? Do they have a place?
Well of course they do, because there are already examples of straw-bale Passiv and very traditional, vernacular-style buildings as well. Passivhaus boxes clever here because it says it's not prescriptive, it's just a standard and that you are free to interpret it in any way you see fit. But that ignores the fact that it's an engineering standard more than an architectural one, a standard whose primary design tool is a spreadsheet (PHPP) not a drawing board. Elegance, in the world of Passivhaus, is simplicity not ornamentation, and whilst there is nothing to stop you indulging in architecture with a capital A, in doing so you veer away from the essential message.
That's not to say that, for all its scientific rigour, Passivhaus has all the answers. No, there are still questions to be resolved, primarily to do with resilience. The three corner stones of Passivhaus are insulation (lots of it), airtightness (v. tight) and ventilation (MVHR please). It works in models and it works in practice. But how will it work over the lifetime of a building? Will the airtightness be compromised by inhabitants putting in cables for their TV sets or cat flaps for their pets? Or just knocking houses about for the fun of it? And what about these ventilation units? Will they get adequately serviced? Will they continue to work as planned? Indeed, will a new certified Passivhaus circa 2012 still be a Passivhaus in 2022, or 2052? If a Passivhaus is difficult to design and build (it is) then it will surely be difficult to maintain?
This was brought out a couple of times by speakers relating what had happened to some of the social housing Passivhaus projects. Some of the tenants had tinkered (i.e. messed up) the MVHR settings, many of them had installed huge plasma TVs (Lord, help us), one kept a window open all winter long so that he could run an extension lead into the garden to power up the jacuzzi. And you could tell the ones that smoked dope from the state of their ventilation filters.
It all sounded just a tad Victorian as these well-meaning philanthropists bestowed heaven-on-earth (aka Passivhaus) on these poor saps, only to find that they are a bunch of undeserving ner-do-wells, intent on a lifestyle of drink, drugs, fatty foods and general sloth. I'm sure that's a total exaggeration, but as always, it's the anecdotes that you remember, not the graphs.
There was lots on retrofit. Cost and test data is still coming in from the RetroFit for the Future schemes which are now complete. It's a much more problematic area than new build because, whilst there is undoubted elegance in creating a genuinely low-energy structure, almost nothing about retrofit could be described as elegant. It's an almighty kerfuffle and it's also incredibly expensive if done to Passivhaus standards, often considerably more than starting again from scratch. This poses problem for enlightened builders because logic would seem to dictate that we would be better to demolish every inefficient house and rebuild our entire housing stock on Passivhaus principles. But of course that ain't going to happen. Not only is there extreme opposition to it from the population at large, but it's also such a vast task that no way would we be able to complete it in a sensible timescale.
What we don't know — cannot know — is what the future holds in terms of energy supply. Will we have got to grips with the supply problem by 2050? Will we have lots of low-carbon energy to burn, or will it be a precious commodity to be husbanded carefully. And how much will it cost? Without this information, we can do no more than guess at how much effort we should make to "RetroFit" our existing building stock.