Thermal Modellers Scheme

What is Thermal Modelling?

With the latest publication of Technical Guidance Document to Part L of the Irish building regulations, it is clear that the elemental thermal performance (U-values) of the building envelope has been further improved in order to limit the primary energy use and reduce CO2 emissions for both new builds and improvements to existing dwellings.

In conjunction with increased insulation levels in the fabric of buildings, heat losses due to thermal bridging have become increasingly important. This in turn has increased the demand for such thermal bridging to be thermally modelled.

As outlined in clause 1.3.3.1 of Technical Guidance Document (TGD) Part L

• To avoid excessive heat losses and local condensation problems, reasonable care should be taken to ensure continuity of insulation and to limit local thermal bridging, e.g. around windows, doors and other wall openings, at junctions between elements and other locations. Any thermal bridge should not pose a risk of surface or interstitial condensation. Heat loss associated with thermal bridges is taken into account in calculating energy use and CO2 emissions using the DEAP methodology.
• There are a number of approaches to make reasonable provision with regard to limitation of thermal bridging, this scheme address item (iii) of clause 1.3.3.2 of TGD Part L namely 1.3.3.2 (iii) use certified details which have been assessed in accordance, and comply, with Appendix D, e.g. certified by a third party certification body such as NSAI Agrément or equivalent or certified by a member of an approved thermal modellers scheme or equivalent for all key junctions.

 

NSAI Thermal Modellers Scheme: Overview

The purpose of this scheme is to allow applicants to register as an approved Thermal Modeller of bridging details and junctions, for the purpose of compliance with Clause 1.3.3.2 (iii) of Technical Guidance Document Part L Conservation of Fuel and Energy - Dwellings.

The registration process is twofold:

Applicants must first demonstrate, by way of written submission, that they have a suitable level of competence in order to register as an approved Thermal Modeller.

Applicants must successfully complete 1x3D thermal bridging calculation set by NSAI Agrément and submit 5 sample 2D details as described in section 5. The Applicant will be assessed by the NSAI Agrément and registered as an approved modeller on a web based register. The modeller will be subject to audits (e.g. annual) by the approval body.

NSAI Thermal Modellers Scheme: Documents

Thermal Modeller Application Form

Guidance on application competency & Thermal Modelling validation exercises