The 2021 update to Part L and the move towards the governments Future Homes Standard has increased the focus on heat loss through thermal bridges in new homes.
Work by the Future Homes Hub goes further and has reported that it is no longer possible to comply with Part L without the use of calculated Ψ values.
Part L defines two methods to assess thermal bridges; individually modelled values or using a database of independently assessed details such as Recognised Construction Details ™ (RCD).
Get started with Ψ value calculations
All junctions considered in these Recognised Construction Details have been modelled in accordance with BRE Report BR 497 -
Conventions for calculating linear thermal transmittance and temperature factors (2nd edition, 2016) with minimum temperature
factors considered in accordance with BRE Information Paper 1/06 - Assessing the Effects of Thermal Bridging at Junctions and
around Openings in the External Elements of Buildings (2006).
In addition, the ψ-values given were produced using Physibel TRISCO software which complies fully with the standard BS EN ISO
10211: 2017 - Thermal bridges in building construction. Heat flows and surface temperatures. Detailed calculations.