Conventions for Calculating Linear Thermal Transmittance and Temperature Factors: (BR 497) (Bre Reports)

Amongst other measures that address the need to reduce CO2 emissions, that of having better insulated buildings requires more sophisticated methods such as numerical modelling to calculate the heat loss caused by thermal bridging at wall, roof and floor junctions and around openings. This guide gives the conventions that should be followed by numerical modellers to produce consistent, reproducible results. For building regulation purposes two key modelling outputs, temperature factor and linear thermal transmittance, are identified. These key outputs will enable designers to confirm the adequacy of particular junction details and help with the development of novel solutions to improve the thermal performance of junctions.