Buildings account for nearly half of the UK’s total carbon emissions and are therefore targeted for significant improvement by regulations. In response to the Energy Performance of Buildings Directive, the UK Climate Change Act 2008 and the goals set by COP26, national regulations are requiring ever more energy efficient buildings.
In the UK climate, heat losses through the building envelope (the shell of a structure separating the outside from the inside environment) account for more than 75% of the total heat loss including air leakage. The thermal insulation provided by the building envelope is key to energy efficiency but thermal bridges, which are weak spots in the insulation, lead to local heat losses that reduce the thermal efficiency. There are cases where it is necessary to detail steel components that penetrate the building envelope or where the structure is connected to foundations or other elements, therefore this should be done without causing excessive heat loss or causing a condensation risk.
SCI has experience on the thermal performance and assessing the impact of thermal bridging in the building envelope from involvement in past multi-year research projects such as TABASCO (contract RFSR-CT-00028) and BATIMASS (contract RFSR-CT-00033). SCI has published several documents on the topic: P410: Thermal bridging in steel construction, which provides guidance on thermal bridging in hot-rolled steel structural frames and P411: Thermal bridging in light steel framing and modular construction, which focuses on thermal bridging in light steel frames.
SCI’s flexibility means we can offer bespoke consultancy by providing thermal modelling analysis and holistic consultancy on the thermal performance of the building envelope by using specialist thermal analysis software. The employed thermal analysis allows the simulation of heat flow effects in a 2D or 3D space and can assess:
- Transmittance of heat losses and thermal performance;
- Risks of surface condensation;
The established heat flow depends on the thickness and thermal transmittance of materials, resistance of air layers and temperature gradient between the defined surface areas of the boundaries of the modelled system. The methodology can include, but not limited to, thermal bridging analysis of each junction undertaken in accordance with EN 10211:2017. The post-processing analysis would involve establishing planar (U-values) or linear (ѱ-values) thermal transmittance performance and risks associated with surface condensation (fRSi value).
The case studies that can be modelled could range from a planar wall element (such as those found in light steel framing applications), to composite junction details, and to a thermal analysis for a whole or section of a building. An example of assessing the performance of a thermal break is illustrated in Figure 1. Further information is found on our webpage and the presentation given on our SCI annual event, found here.

Figure 1: Thermal modelling of a balcony detail with no thermal break and with thermal break between steel and concrete
For more information or if you are in need in SCI’s services in this field please contact Constantinos Kyprianou at SCI.