Thermal Bridge Assessment
A thermal bridge is a particular area of a building construction which has a higher heat loss than the surrounding area. A thermal bridge may be assessed in order to quantify the additional heat loss in this area and to determine the risk of condensation and mould growth on the building element due to a lower surface temperature caused by the thermal bridge. Generally speaking, there are two types of thermal bridges:
- Repeating thermal bridges such as a timber or metal frame structure which penetrates the main insulation layer which result in additional heat loss in roofs, walls etc. These repeating thermal bridges are generally accounted for in U-value calculations
- Non-repeating thermal bridges which cause heat loss at junctions between building elements such as wall to floor, wall to roof and around windows.
In the second case the additional heat loss due to non-repeating thermal bridges is addressed by calculating what is known as the ‘psi’ value and the risk of surface condensation is assessed by calculation of the ‘fRSI’ value.
There is a legal requirement in TGD Part L for building designers to identify and address potential thermal bridges:
“18.104.22.168 To avoid excessive heat losses and local condensation problems, reasonable care should be taken to ensure continuity of insulation and to limit local thermal bridging, e.g. around windows, doors and other wall openings, at junctions between elements and other locations. In general, thermal bridges should not pose a risk of surface or interstitial condensation.”
BET thermal modellers carry out accredited thermal bridge analysis to the latest regulations and standards using advanced finite element analysis software, whatever your requirements get in touch with us today.