Go to Forum Home Building Refurbishment and Retrofit airtightness in refurbishment

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    • #30683

      Has anyone managed to achieve high airtightness levels in a refurbishment of a house in the UK? or do you know anyone who has?
      Some projects in Germany have been certified to achieve 0.2 air changes per hour in refurbishment.
      Is there a secret we don't know about or is it just good design, detailing and workmanship?

    • #33895
      David Olivier

      The UK hasn't managed 0.2 on new build. The best I know of ever is about 1.1 (a house built near Reading in 1995 from concrete/BECO). Paul J might know of better figures as he tests lots of buildings.

      I'm suspicious about 0.2 m3/m2hr @ 50 Pa on a retrofit. The tightest new build ever, anywhere on the planet (Canada), was 0.15.

      I hope you are using units of m3/m2hr at 50 Pa. 0.2 ac/h @ 50 Pa can be fairly easily achieved on a large enough building, so long as it has an enormous volume and a relatively small surface area.


    • #33896

      Thanks David
      That makes sense now the German measurements seems to be always in airchanges per hour.

    • #33897
      Mark Siddall

      “So long as it has an enormous volume and a relatively small surface area”

      You mean like the Tardis?


    • #33898
      Nick Grant

      Also beware units of litres/second/m2 @ 50Pa which I just spotted in the latest PH proceedings!

      0.2 l/s/m2 = 0.7 m/h

      It's worth repeating that the structure should not penetrate the airbarrier – rafters, purlins, floors etc.


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