Passive housing in Austria

IT is almost eight years ago, since I was part of a 12-strong delegation from Scotland that visited various housing developments in Austria as part of a larger group of 50 architects and (materials and methods) specifiers from all over Britain. 

At the time, I was working, among other things, as the co-ordinator for the Fife Construction Forum, a construction industry support group. I still am seeking to explore how new approaches to building energy management can be incorporated into all types of buildings.

Visiting sites from Innsbruck down to Vienna, we explored a broad variety of different ‘Passivhaus’ developments from new-build blocks of flats to refurbished school buildings, where we were told the energy efficiency was increased by 94 per cent. The tour was organised by the Austrian Trades Commission with the Scottish delegation organised by Fife Council.

In Scotland, we are now more familiar with the concept of the ‘Passivhaus’ than we were back then.

But only just.

The focus of the visit to Austria was on mainstream projects – as opposed to experimental, one-off or prototype ones.

It was considered that Austria was about ten years ahead of Scotland in the mainstreaming of these developments and the intention was to help close this gap by bringing back some of this knowledge, inspiration and proof of concept.

In simple terms, ‘Passivhaus’ is about a building out any draughts or cold spots, with the result being low energy bills. What’s not to like about that?

But it involves more care and a little extra cost at the build stage than might otherwise be the case. 

And until we switch from a fixation with initial build costs, so that we consider the cost of a house over its expected lifetime, then we might never replicate what is often commonplace abroad.

Passivhaus – in my view – is about super-insulation plus a means of expelling moist air – that we breathe out, from taking showers, drying our clothes and which is just simply part of our climate. As many of us are all too aware, moist warm air is a recipe for damp and mould.

To let moist air out and fresh air can be done by simply opening a window, having slits cut into our window frames or peppering the building with air vents.

But that’s to allow heat out and draughts in. Heat that we will have spent good money, bringing into the house.

The good news is that technology has moved on these last few years. It’s called ‘mechanically-ventilated heat recovery’ and works by fresh air being brought in, from the outside, and being warmed – via a ‘heat exchanger’ – by the moist air that is being expelled.

In other words, the warmth of the moist air being expelled is being transferred (or exchanged) to the colder fresh air being brought in.

And that’s why we need to think ‘whole house’ costs: because MVHR is kit that costs. Prices are dropping all the time as the technology becomes more and more established and kits are available for about £2,500 for a typical house. 

In Austria, eight years ago, the visits included apartment blocks as well as individual houses, which allowed for MVHR to be done centrally.

And with at least one block, clever design meant that all the service piping (in and out, including water and waste) had been grouped together in the one void space that could be then easily sealed, to add to the insulation performance.

I learned lots. Too much for an essay of this length.

And among my several conclusions? 

Passivhaus (or equivalent low energy consumption standard) is now a standard production technique in Austrian housing.

It is also being more slowly adopted in commercial buildings such as hotels and offices and the final challenge is the refurbishment and renovation of historic buildings.

I also noted that there is a full supply chain in place – by that, I mean that all the required materials and technologies have moved from the experimental or prototype stage to ready availability as complete, integrated systems with full guarantees and full technical support.

Michael Kampff is an independent consultant and facilitator

Pictured: Pernerstorfergasse – new-build social housing project of approximately 100 flats. Car parking is underground with one parking space per apartment.  There are also the communal facilities such as a laundry. Picture courtesy of Michael Kampff.

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