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Direct from Frankfurt: the latest in Passivhaus

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Diana Dina of bere:architects reports from the 17th International Passive House Conference

I headed off to Frankfurt to the 17th International Passive House Conference without really knowing what to expect. I did have some rather mundane questions related to Passivhaus projects I am working on, like ‘what do I do with the timber joists when I use internal insulation if I don’t want to take the joists out because it’s too costly’, or ‘ if it’s a multi-residential building, should I go for a centralized ventilation unit, or one per flat’, and so on. During the three days spent in Frankfurt, I managed to find some answers and I also came across new approaches which reminded me that people everywhere are more than willing to share their knowledge about how to make better buildings. All you have to do is ask.


This idea of sharing knowledge and skills was highlighted by the launch of a Memorandum for a new way of building. It’s an appeal from fellow industry professionals to their peers to act to achieve low energy and environmentally friendly buildings, even ‘before regulations and statutes demand it.’ Have a look (it’s concise!),  and sign if you connect with the ideas presented in there. I did!

The conference gathered people from around the world and showed during a multitude of presentations spread over two days that ‘Yes, it works’ for new build, retrofit, and also for historic buildings (the 3ENCULT project). The almost 700 listed attendees included architects, engineers, planners, manufacturers, and students. Amongst the UK delegation were architects (Anne Thorne Architects, Architype, bere:architects, LEAP), consultants (Brooks Devlin, Warm, Green Building Store), and contractors (Dominic Danner from Durkan), as well as start-up practices (Transition by Design).

If we take a step back and look at the concept, it’s a pretty straightforward idea, which deals with minimising the energy consumed in a building and maximising the comfort for the occupants. But there is a little more needed to make a good building. Architects need to do their bit and use their creativity to integrate the PH concepts into design-led buildings. When, if, and how that happens is another equally interesting story.

Discussions about the design quality of Passivhaus buildings were peripheral to the whole event, touched upon only here and there: the Austrian State prize for architecture and sustainability was presented at the conference, since this year it went to a Passivhaus building in Vienna by Querkraft Architects. It was during the tours to both completed and on site Passivhaus public buildings in Frankfurt that the quality of the architectural design was particularly impressive. Could it be because all the projects we saw were the result of architectural competitions?

The city of Frankfurt has adopted legislation which requires all public buildings be built to Passivhaus standard. At the conference I met local city planners who were there to get up to speed on what was new, because they need to. The regulation is pushing people to learn about low energy design. I was surprised by this top-down approach, which is the opposite from what is happening in the UK, where professionals are pushing Government towards real, meaningful, energy efficient measures. What they received so far is a little Green Deal.

The buildings I saw on the Sunday tour were:

-         A gymnasium, timber structure, by D’Inka Scheible Hoffmann Architekten BDA The project is a prototype to be used on various site locations, with minor changes to external cladding materials to match the local built context. Eight have already been built. Since the first site had a difficult north orientation, the design was already tested and ready for any other site.

Gymnasium D Inka Scheible Hoffmann 1

-         A multi-residential development in the Riedberg neighbourhood, almost completed (several units were already occupied), by Albert Speer und Partner

Multi residential Albert Speer und Partner

The architect who met us on site explained that the practice can develop at least five different Passivhaus wall build up options, but the quality and price of the materials used (ranging from EPS to more environmentally friendly materials), as well as the effort put in the design, depends on the client’s budget and cost expectations. And while they strive for designs which do not cry out ‘ this is a Passivhaus’ building, in the interior courtyard you could find the typical ‘low-energy -no -thermal -bridge -independent -from -the -building’ balconies – and I wondered if just a couple of thermal break connectors could not have solved the problem in a more elegant manner. Balancing the budget also meant using UPVC triple glazed windows, not certified but with good thermal performance, but expensive vacuum insulation for level access to loggias and roof terraces.

-         A school and sport centre, also in Riedberg, by Ackermann +Raff Architekten, due to be opened next week. In addition to atriums, nighttime ventilation and a centralised MHRV unit connected to motion sensors in classrooms, the building had airy interiors and a lovely feel, a good example of engineering integration and collaboration.

School Ackermann und Raff

As a note, all projects had decoupled ventilation and heating strategies. In all cases, the heating was connected to district heating networks, which, as someone pointed out, are more efficient than individual heating systems and greatly reduce the primary energy consumption.

During a friendly chat with the head of a German housing association, I learned that for new build developments, they organise architectural competitions in collaboration with the local architects’ institute with selected architecture practices. They also invite two to three young practices to any competition. I left the event dreaming of UK housing associations organising competitions with the RIBA for Passivhaus projects. Bere:architects developed  two passive houses in Wales for the United Wesh Housing Association – but I haven’t heard of any other similar opportunities lately for architects to promote low energy, quality design.

So, what’s next? Based on the ‘hard facts’ presented, which show that with careful design the standard delivers very energy efficient buildings, Dr. Feist pointed to the future: near zero carbon buildings. Once the energy demand is lowered, and renewables are used for the little energy that is required, the only issue that remains is how to store the renewable energy, so that it becomes readily available and dependable. The answers seem to lie with mechanical, chemical and thermal storage. Another way forward is to learn from past projects which have pioneered solutions before us. One example is Korsgaard and Esbensen’s zero energy house built in Copenhagen in the 70s, which featured passive measures and a thermal store. The project won this year’s Passive house Pioneer Award.

The aim was clear and bold: getting Germany off coal and oil by 2050, to set a precedent for the rest of the world. I was surprised by the terminology used by everyone, ‘energy revolution’ and ‘energy transition’, which reminded me of Jeremy Rifkin’s Third industrial revolution, (AJ . It feels like Germany is making very decisive steps ahead, while the rest of us are still waiting to see the results before deciding whether to follow.)

Oh, and the answers are:

-         Mr Ulrich Rochard of Pouget Consultants mentioned that an upcoming study by Fraunhofer Institut will show that where internal insulation is applied, in order to avoid interstitial condensation at the end of the timber joists, three issues must be addressed: protection of the exterior wall from driving rain, an airtight connection around the joists, and the use of open diffusion insulation systems which allow any seasonal condensation to dry out.

A WUFI analysis of the actual wall construction to check moisture build-up would be advisable, as Joseph Little of Joseph Little Architects (Ireland) pointed out in his presentation.

-         Centralised or decentralised, that was the MHRV question. Apparently this is best discussed for each project with your M&E consultants, ventilation system providers and cost consultants.

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