November 18 2011

Retrofit Passivhaus: A Good Approach for Refurbishing Existing Buildings in the United Kingdom?

A Passivhaus (the German sustainable design standard) uses 10% of the energy of a typical central European house, meaning a 90% energy saving.

The buildings that exist today will account for over 70% of the total building stock by the year 2050, so how we make them energy efficient is very important.  The United Kingdom’s first Retrofit Passivhaus project was completed in early 2011.  It is recognized that, particularly orientation (which affects solar gain), is unchangeable in existing homes, but it is still possible to retrofit to Passivhaus standards.

As part of the Retrofit for the Future scheme 64 Midmoor Road, an existing house in London, was refurbished by:

  • Removing all wall linings, plumbing & electrics;
  • New rear external insulation & triple glazed windows fitted;
  • New continuous airtight layer of Oriented Strand Board (O.S.B)/Plaster.

The project, architect Robert Prewett, suggests that attempting to reach Passivhaus standards without removing all the internal linings would make the task considerably more difficult and potentially risk the existing fabric, because e.g. damp may not be obvious.  Air leaks resulted between new and old plaster and the MVHR and ducts were difficult to fit in.  This suggests that the Passivhaus approach should only be considered where no original features require being retained.

Traditional buildings behave in a different way from modern buildings in relation to moisture, air movement and thermal performance, and are more likely to be built from porous “breathable” materials which allow natural air movement and deal with moisture build up through evaporation.  Many United Kingdom homes have successfully dealt with the weather for 100 years.  Applying modern design methods is not always appropriate and can lead to moisture build up and fabric deterioration. Only research on the long term effects of Retrofit Passivhaus will prove how appropriate a method it is for existing buildings.

There is also the issue of how truly ‘Passive’ Passivhaus can be with MVHR at its core! Passive solar design is a non-mechanical strategy. Is this what we should be focusing on instead?

Credits: Images linked to source

Laura Paterson

Laura Paterson is a graduate of the Mackintosh School of Architecture in Glasgow and Edinburgh College of Art. She holds a B.Arch in Architectural Studies and a PG Diploma in Architecture and is currently studying for a M.Sc Architecture: Advanced Environmental and Energy Studies with the Centre for Alternative Technology, Wales. A qualified United Kingdom architect, Laura was born and still lives in Edinburgh, Scotland. Edinburgh, with its a rich source of historic buildings was what inspired her to study Architecture. With experience in refurbishing Victorian houses, Laura has a particular interest in sustainable, low carbon refurbishment of historic buildings and passive approaches to building design.

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This entry was posted on Friday, November 18th, 2011 at 9:49 pm and is filed under Architecture, Energy, Environment, Environmental Design, History/Preservation. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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3 Responses to “Retrofit Passivhaus: A Good Approach for Refurbishing Existing Buildings in the United Kingdom?”

  1. Michael Says:

    I’m sure the under floor work would be the most costly and disruptive. What sort of saving would be lost if the ground heat exchanger was omitted? I imagine in most cases (where the ceiling height allowed) the floor insulation could be achieved by building the floor up rather than digging down but this would vary from house to house

  2. Laura Paterson Says:

    Thanks for the comment Mike, agree the floor work to an exisitng building would be disruptive, and raising the floor creates issues of accessibility – so not a straight forward solution!

  3. The Nation’s First Net-Positive Planned Community: NewPHire, North Carolina | The GRID | Global Site Plans Says:

    [...] to spread globally today. Previous articles from The Grid on the topic may be found at “Retrofit Passivhaus: A Good Approach for Refurbishing Existing Buildings in the United Kingdom?“, “Is Whole House Mechanical Ventilation with Heat Recovery (MVHR) Really a Passive [...]

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