Go to Forum Home Materials and products Insulation Declared and Design Thermal Values – SOLVED!

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    • #31298
      Mark Siddall

      read on for background or skip to last post for answer.

      :)Though that the attached document, and the email below, may be useful for kicking off the discussion. Should we be considering DIN standards in UK PassivHaus buildings? Or should we stick to EN standards?


      Original Message

      > From: Kara Rosemeier
      > Sent: 07 May 2010 03:05
      > To: Siddall, Mark
      > Subject: Re: Declared and Design Thermal Conductivity
      > Some thoughts on this, from the back of my head:
      > there was an outcry in Germany when CE labelling was introduced. Before this, Germany had a thermal conductivity
      > category system, with groups in 0.005 intervals (for simplicity, the leading zero and the
      > decimal point were omitted in the label). Tested dry lambda values got a humidity surcharge, and were then rounded
      > upwards to the next 5 at the 3rd decimal. A material with a thermal conductivity (with humidity
      > surcharge) of 0.033 would thus have been in the 035 group – the 0.002 was viewed as a safety margin.
      > Mandatory CE labelling changed this, which led to much uncertainty.
      > Last time I checked, Germany adopted the following procedure: declared values get a 20% (no ongoing third party
      > monitoring of production) or 0% surcharge (ongoing third party monitoring) to arrive at design values. Only design values
      > must be used for Code calculations. Not sure if that is still the current situation.
      > Yet, this definition of design value is not identical with the one in 10456; here, design seem to mean assessed under
      > specific conditions, deviating from the standard conditions, eg other rH etc. Thus, the calculation prodecures given would
      > eg tell how a material that was assessed at 50% rH might perform at 80% rH – at least that is my reading.
      > 10456 says nothing about safety margins or ongoing monitoring.
      > Thickness, eg with XPS, from memory might indeed have an impact on thermal conductivity; not sure if I still get this
      > together correctly, but this had to do with the foaming agents used (and also not sure if this still applies now that
      > we switched to less ozone depleting agents). If my memory serves me right, this should therefore not be an
      > issue with blanket type or loose fill insulation. I believe not even with EPS. Why the heck can there not be clear,
      > internationally applicable regulations to deal with these issues? And why do we need 6 sets of boundary conditions to
      > evaluate the physical properties of materials? I am currently trying to figure out if glazing that has an NFRC U-value has
      > the same EN U-value (for some reason, US measuring procedures are the default in NZ, and I am not sure if a glazing U-
      > value of, say, 1.2 here equals what I am used to from Europe, or is
      > a different animal altogether). Sigh!
      > Kara

      Any thoughts?


    • #37179

      1. I suggest we start a drop box folder for each working group and develop a limited suite of documents starting with a spreadsheet with WG participants. To be approved by Peter Warm, Mark S and Nick Grant. If you agree I or Nick can set up. Mark and Peter – are you familair with 'dropbox'?

      2. couple of suggestions for participants of this Working Group

      • Jeremy Richings – Technical Director with Permarock would be good – eps and neopor type – he contributed to the gold guidance.
        Phil Rigby from Knauf Insulation – glass fibre and some foam boards? Knauf have been involved in 3 PH certified bgs

      David olivier and Alan Clarke?

      Can we start with a clear statement from PHI on the formal requirements they expect from now on in the UK for PH certification? Then we can start to unpick the way to get from A to B where A is what values UK uses across insulation types and the inconsistencies therein

    • #37180
      Nick Grant

      I'm a bit wary of Wiki and Drop box for ourselves but agree would be good to feed into what is already happening. Suggest we keep it simple and that document production is trusted to individuals who put round for peer review.

      Forum discussion can be fast and dirty.

    • #37181
      Nick Grant

      Great news Pete.

      Can we announce on the building simulation board which is visible to all members?

      Good to see Sally today, hopefully useful all round.


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