Thermal Bridge Modeling

on Monday, 02 February 2015.


Greenbox Associates specialise in the calculation and analysis of thermal bridges using bespoke modelling software PsiThem. PsiTherm is ISO validated software used to determine heat flow and surface temperatures of 2D and 3D junctions and to calculate psi values. Modelling and reducing psi values improves the thermal performace of a building, increases the SAP rating and helps meet both Fabric Energy Efficiency (FEES) and Dwelling Emission Rate (DER) requirements for Part L1A Building Regulations compliance.

Thermal bridges

As homes become more energy efficient, the heat loss through junctions become more significant and reducing this can help both improve the thermal efficiency of the home and reduce 'cold bridging'. Using bespoke thermal bridges can assist in achieving Part L1A 2013 compliance without the need for additional renewable energy or other measures. This can reduce cost and improves the quality of the building fabric by reducing condensation risks and cold spots.

The thermal bridge models below show an timber frame corner which has been desiged to reduce thermal bridging to a psi value of 0.034 W/mK

corner 1

corner 2


 A vital element of Passivhaus design is the exclusion of thermal bridging at junctions. Through calculating yours designs, Greenbox Associates can help you understand the effect of heat flow at junction details at the early stage. This allows us to calculate accurately heat losses and gains in PHPP. We can also provide the correct calculations to support the certification of your building.

cantilever floor 1cantilever floor

The detail above shows a cantilever floor detail above bifold doors. Externally measured this detail has a psi value of 0.055 W/mK which can be divided between the lintel, intermediate floor and first floor.