Thermal image of window/wall junction thermal bridge

Thermal Bridge Assessment

Thermal bridges are parts of a building that conduct more heat than the surrounding building elements, either due to different levels of thermal conductivity, or places where internal and external surface areas are different (for example external corners of a building). Most building junctions  represent some kind of thermal bridge (e.g. where walls meet each other, or join the roof or floor).

Thermal bridges cause additional heat flows, adding between 5% and 30% to the overall energy use of a building. They can also lead to reduced internal surface temperatures, bringing an increased chance of condensation and mould.

Thermal camera image of a window/wall thermal bridge

Thermal camera image showing heat flow and temperature differences at a thermal bridge where a window frame meets a wall

Building Regulations require thermal bridging to be limited. If Approved Construction Details (ACDs) are not used (standard construction details which have had the thermal bridges calculated), then the extra heat flow (Psi or Chi value) through each thermal bridge should be calculated. If ACDs or calculated values are not used then the Building Regulations define default values which must be used for energy assessment – these are set at relatively high levels, in order to provide a conservative estimate of energy efficiency.

Calculating the Psi and Chi values of the thermal bridges in a building provides a much more accurate overall energy assessment. Well designed building junctions are likely to have Psi values much lower than the defaults. Calculating them can negate the need to add additional insulation elsewhere in order to meet SAP or other energy efficiency targets, so the cost of having them calculated can result in an overall cost saving.

The cost of thermal bridge analysis will depend on the number of different junctions to be assessed and on their complexity. A full quote will be given after viewing the details to be analysed.