The Passivhaus Style

As you may have noticed from all the (t)wittering a few weeks ago, I was lucky enough to be offered a place on a field trip to Germany to study Passivhaus construction principles. As my practice continues to try and raise the energy efficiency bar in the social housing sector and travel along the seemingly never ending path to zero carbon (thanks to the fact that we can’t agree a destination), adopting Passivhaus strategies makes perfect sense.

Perfect sense – that’s the very essence of Passivhaus thinking you might argue, its seemingly unarguable logic that simply asks that we build well insulated, draft free, carefully detailed, properly ventilated buildings. What’s not to like?

There are a full set of photos available on Flickr, more notes and audio in an Evernote folder (although the audio is too quiet unfortunately) and if that’s not enough there’s even a hand crafted booklet you can download and fold yourself thanks to bookleteer.com. Never let it be said that I don’t give value for money.

The trip began with a presentation on board the mothership – the Passivhaus Institute in Darmstadt. Our host talked us through the key principles of super insulation levels of below 0.15, super air tightness that allowed no more than 0.6 air changes per hour, super rigorous detailing that eradicated connections between the outside and the inside, super seductive triple glazing products and ventilation heat exchangers that performed at an efficiency that was, well, super. The examples shown to us offered timber frame construction for new build and wrapped existing buildings in a cozy blanket and all new air tight skin. The almost hermetically sealed results providing their inhabitants with a life free from cold and heating bills. We left shaking our heads at the insanity of the normal, slapdash world of construction then shook them again at the thought of the work in front of us required to fix it.

A trip to building membrane supplier Pro Clima came next. An impressively detailed, technical description of the science of moving moisture around the building proved to be the perfect accompaniment to the previous day’s discussion on air tightness. Stop the wind blowing in, but let the moisture out. Graph after graph and detail upon detail proved it beyond doubt, but you should never underestimate the value of the ‘you mean it’s a bit like Gore-Tex?’ moment to really convey the core principle.

Lothar Moll, Pro Clima founder, gave us a demonstration of their products and detailing recommendations allowing the geeks amongst us to stroke a few things and get up close. The gale blowing through the tiny punctures he made in the membrane for the final demonstration gave us further proof of the unassailable logic.

He made a passionate plea to use that same logic when considering whether to demolish or refurbish, pointing out that when you do the maths alone it often doesn’t make sense to retain existing buildings. A tidy balance sheet alone doesn’t necessarily make for a healthy society though, despite what our coalition might think.

On from there to some actual examples of Passivhaus buildings, with Ludwigshafen Brunck Quarter first on the list and a tour from the architects Luwogue Consult. A project that had created new build Passivhaus properties:

As well as refurbished existing dwellings:

A key feature worth noting here is the use of level changes and the acceptance of basement parking, lifting the floor slab and the tricky insulation details up out of the ground. Not so straightforward perhaps in a world of Lifetime Homes and Secured By Design guidelines here in the UK social housing sector, even if the rules have been slightly loosened lately.

Inside we found a sensibly laid out floor plan around a well placed service core and kitchen and a better finish quality to important elements like stairs then we might have found at home. The connection from kitchen and hall space to the stairs and first floor must surely create some noise problems though. The temperature? Warm. Everywhere. More on that later.

Next we visited Hoheloogstrasse and here felt the shame of our tardy arrival to the Passivhaus party as our guest seemed genuinely uncertain about what to tell us at first, given that we were making a fuss about a 5 year old project whose principles were now almost standard practice.

We’d spent hours being talked through the Passivhaus Haynes Manual and had poured over every component in this high performance machine for living in but that afternoon had been our first look at all the parts assembled and being test driven. The obligatory canter through the Top Trumps statistics had told us what we’d come to expect of the fuel consumption and efficiency, but what of the aesthetic? A pattern had been evolving in the images in the lectures and the previous project and Hoheloogstrasse continued in the same style.

Rendered external insulation that leaves little opportunity for relief or material change is perhaps the most obvious common feature and combined with the metal clad windows a somewhat industrial style ensues. There’s a more subtle issue here though that’s also a direct result of the science and it’s the simple fact that you can’t fix anything to, or through, the building. Projections – those parts of a building that hint at the heart of a structure and it’s spaces – become divorced from the main body of the architecture. The rigorous avoidance of any ‘cold bridge’ that might allow heat loss to seep out through a continuous material conducting warmth wastefully outwards results in the architectural equivalent of a restraining order.

Don’t touch me, says the increasingly uptight building, leaving balconies, canopies and even mail boxes to shiver in the cold. It was with some disappointment that our host had to acknowledge a small connection from the balcony structure to the building, included thanks to concerns about wind load, that resulted in a minor flaw in the thermal performance. A brief moment of almost Ballardian eroticism as the coming together of body and metal was acknowledged in slightly hushed tones.

I’m exaggerating to make a point of course but this seems significant. The insulation strategy predominantly used in this type/size of building combined with the casting out of architecture’s most fickle elements that usually flirt with both inside and out threatens to create a depressingly homogenous Passivhaus Style. However, a problem can soon become an opportunity once you’ve spotted it and I wonder about a future that capitalises on these issues and plays with the possibilities. An embracing of the stand-off facade that dances to its own tune in a manner not too dissimilar to the work of FAT perhaps? Or the suburban stage set imagined by Archigram?

On smaller scale buildings and simple masonry cavity construction the question of material choices should be wider though and the buildings listed in the UK Passivhaus Open Days this weekend certainly seem to provide some variety of language and vernacular. I’d be interested to hear from anyone who visits one. Then next week we’ll talk about that perfect temperature…