The need for qualified Thermal Modelling practitioners arises from the requirement for increased performance of buildings under the Part L of the Building Regulations.
Thermal modelling is a complex process which demands an understanding of applied building physics principles and an ability to use a variety of inter-related calculation software applications to measure performance in two and three dimensional assemblies. Its correct use is central to energy-efficient & healthy sustainable building design and to achieving long term performance of new build and retrofit building solutions.
With the latest publication of Technical Guidance Document to Part L of the Irish building regulations, it is clear that the elemental 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 coldl bridging has become increasingly important. This in turn has increased the demand for such thermal bridging to be thermally modelled.
As outlined in clause 220.127.116.11 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, one approach is use details certified by a third party certification body such as the NSAI.
NSAI Approved Thermal Modellers Scheme
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 18.104.22.168 (iii) of Technical Guidance Document Part L Conservation of Fuel and Energy – Dwellings.