[null, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/d/d3/BR_497_front_cover.jpg", "src": "https://www.designingbuildings.co.uk/w/images/d/d3/BR_497_front_cover.jpg", "formatted_filename": "BR front cover", "alt_text": "BR 497 front cover.jpg"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/3/36/Dust_290.png", "src": "https://www.designingbuildings.co.uk/w/images/3/36/Dust_290.png", "formatted_filename": "Dust", "alt_text": "Dust 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/6/68/Building_a_safer_future_290.png", "src": "https://www.designingbuildings.co.uk/w/images/6/68/Building_a_safer_future_290.png", "formatted_filename": "Building a safer future", "alt_text": "Building a safer future 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/c/ce/Building_services_analytics_290.png", "src": "https://www.designingbuildings.co.uk/w/images/c/ce/Building_services_analytics_290.png", "formatted_filename": "Building services analytics", "alt_text": "Building services analytics 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/d/da/Waste_and_resources_strategy_290.png", "src": "https://www.designingbuildings.co.uk/w/images/d/da/Waste_and_resources_strategy_290.png", "formatted_filename": "Waste and resources strategy", "alt_text": "Waste and resources strategy 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/6/6d/Skills_290.png", "src": "https://www.designingbuildings.co.uk/w/images/6/6d/Skills_290.png", "formatted_filename": "Skills", "alt_text": "Skills 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/f/f6/Grunge-1245651_290.png", "src": "https://www.designingbuildings.co.uk/w/images/f/f6/Grunge-1245651_290.png", "formatted_filename": "Grunge", "alt_text": "Grunge-1245651 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/8/87/Conservation_wiki_290.png", "src": "https://www.designingbuildings.co.uk/w/images/8/87/Conservation_wiki_290.png", "formatted_filename": "Conservation wiki", "alt_text": "Conservation wiki 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/0/06/Improving_Quality_in_the_Built_Environment_290.png", "src": "https://www.designingbuildings.co.uk/w/images/0/06/Improving_Quality_in_the_Built_Environment_290.png", "formatted_filename": "Improving Quality in the Built Environment", "alt_text": "Improving Quality in the Built Environment 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/6/61/Brewery_Site_Leeds_290.png", "src": "https://www.designingbuildings.co.uk/w/images/6/61/Brewery_Site_Leeds_290.png", "formatted_filename": "Brewery Site Leeds", "alt_text": "Brewery Site Leeds 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/0/0d/Douglas_Sea_Terminal_Building_290.png", "src": "https://www.designingbuildings.co.uk/w/images/0/0d/Douglas_Sea_Terminal_Building_290.png", "formatted_filename": "Douglas Sea Terminal Building", "alt_text": "Douglas Sea Terminal Building 290.png"}, null, {"document_url": "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors", "unformatted_src": "/w/images/8/8e/Dr_Long_Seng_To_290.png", "src": "https://www.designingbuildings.co.uk/w/images/8/8e/Dr_Long_Seng_To_290.png", "formatted_filename": "Dr Long Seng To", "alt_text": "Dr Long Seng To 290.png"}, null]



Last edited 17 Sep 2017 

Conventions for calculating linear thermal transmittance and temperature factors

On 3 June 2016, BRE published Conventions for calculating linear thermal transmittance and temperature factors (BR 497 2nd edition), written by Tim Ward, Graeme Hannah and Chris Sanders. Well-insulated buildings require sophisticated techniques to model heat loss caused by thermal bridging at wall, roof and floor junctions and around openings. Thermal bridging at these junctions can add significantly to fabric heat loss and cause localised reduction in internal surface temperatures, which can lead to surface condensation and mould problems. A more detailed calculation method for U-values, as defined in BS EN ISO 6946:2007, has been introduced to take account of these repeating thermal bridges.

The BRE guide provides the information needed to carry out these calculations so that different users of the same software package or users of different software packages can obtain consistent and reproducible results. It is intended for use by designers and numerical modellers.

For building regulation purposes two key modelling outputs are identified:

These outputs enable designers to assess junction details and develop novel solutions to improve thermal performance.

The second edition of the guide has been updated to include additional junction types and information about how they should be modelled, as well as worked examples giving the determined values of linear thermal transmittance and temperature factors.





Retrieved from "https://www.designingbuildings.co.uk/wiki/Conventions_for_calculating_linear_thermal_transmittance_and_temperature_factors"

