Thermal Bridge Software

Thermal bridge calculation is the technical procedure used to assess localized heat loss at points where geometry, materials or construction discontinuities alter the heat flow through the building envelope. It is used to quantify linear thermal transmittance and assess the risk of mould or surface condensation.

The calculation is necessary when carrying out building energy assessments, preparing technical documentation, checking localized heat loss or assessing the risk of mould formation in critical areas of the building envelope.

The Ψ (Psi) coefficient is the linear thermal transmittance of the thermal bridge. It represents the additional heat loss along the junction line between building elements, for example between a wall and a floor slab or between a wall and a window or door frame.

Thermal bridge atlases make it possible to use tabulated values for common configurations; finite element method (FEM) calculation, on the other hand, makes it possible to model the actual construction detail and obtain more accurate results for specific geometries, materials and boundary conditions.

Dedicated software such as TerMus BRIDGE simplifies geometric modelling, material definition, boundary condition settings and the numerical calculation of linear thermal transmittance, heat flow and surface temperatures, reducing errors and processing time.

Numerous configurations can be analysed, including:

• wall-window or door frame junctions
• wall-balcony junctions
• wall-intermediate floor slab junctions
• wall-ground floor slab junctions
• wall-roof junctions
• roller shutter boxes
• junctions with unheated spaces or the ground

Yes, one of the purposes of this calculation may also be to assess the risk of mould formation. The calculation determines critical surface temperatures and factors used to assess mould risk, allowing the most problematic construction junctions to be identified in advance.

The following data is generally required:

• junction geometry
• construction layers
• thermal properties of the materials
• boundary conditions
• indoor and outdoor temperatures
• any contact with the ground or unconditioned spaces

The most useful results include:

• linear thermal transmittance Ψ
• heat flow
• linear thermal coupling coefficient
• temperature distribution
• isotherms
• mould risk assessment

Not always. Compliant atlases may be used for standard configurations; for complex details, non-standard solutions or specific assessments of the actual behaviour of the junction, FEM is the most reliable choice.

Thermal bridge calculation is used by engineers, architects, building services engineers, energy assessors and consultants involved in the design and assessment of the building envelope.