The basics of Part L Thermal Modelling Building Regulation compliance – Part 2

This second post continues on from The basics of Part L Thermal Modelling Building Regulation compliance and delves a little deeper into the reasons why Thermal Modelling is critical to house design.

One of the two registered NSAI Thermal Modellers mentioned in the above post is Andrew Lundberg who runs Passivate which is still the “first and only Independent Nationally Accredited Thermal Modelling service throughout Ireland & the UK”. Andrew is also a lecturer at Dublin Institute of Technology (DIT) in Thermal Bridge Assessments.

The brochure on the DIT course ‘DT775b CPD Diploma (Thermal Bridge Assessment’ outlines the course objectives and that the programme is recognised by NSAI and leads to exemption from Part 2 of the registration process, with a related reduced fee.

I am mentioning this because the following slide presentation from Andrew (here on the Passive House Association of Ireland (phai) website, brilliantly explains how important Thermal Bridge Assessment is.

Does Thermal Bridge Detailing Really Matter – Andrew Lundberg

There some very important key items that relate to the previous post and the two posts on the BRegs blog on Part L:

1. When using all the Acceptable Construction Details exclusively, and therefore be able to input the lower 0.08W/m2K y-value figure in DEAP still does not give a values specific to your building unless the tables Appendix D of Part L are used. gives details on when the lower and higher values can be used AND a Thermal Bridging Application HERE

Instructions for using the SEAI Thermal Bridging calculator are HERE

The question you need to ask therefore is:

Who has done these calculations for you to ensure compliance with Building Regulations? Your architect? Your engineer? Your BER Assessor?

2. Where non-standard construction details are used, the higher 0.15W/m2K y-value figure is used in DEAP BUT it still means you (as Designer) ‘have to analyse every non-standard junction in accordance with the conventions’. This means that although the DEAP calculations would be correct there still is a huge risk where you haven’t analysed a specific non-standard detail. There is therefore a risk of condensation/mould growth and/or excessive heating bills where inadequate attention is not given to the Thermal Assessment calculations where the detail is not covered by any of the Acceptable Construction Details.

nb Both the Engineers and architects run CPD courses on Thermal Bridge Assessments:

The next post will take us back to how Certified Passivhaus deal with the Thermal Bridging and Certiication problem…

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