Psi – Value Calculations

Psi-values in design

With the amendments to the building code in 2021 (Part L) the expectations of the regulations changed. According to the detailing of the project, we often find that using generic values for heat loss from previous calculations are insufficient. Thus it is essential to perform the fresh calculations required to investigate the specific heat loss issues according to the properties of the materials being used. So, previously design teams did not have to pay too much time and attention to these details. Now it is important that they know the Psi-values (and U-Values ) of their proposed building as early as possible in the process.

The Psi-value analysis, also known as ‘Linear Thermal Bridging Analysis‘, is a method used in building construction to assess the heat loss or gain through structural components that interrupt the insulation layer of a building envelope. Psi represents “thermal transmittance”, and it is expressed in watts per meter-kelvin (W/mK).

In a building, thermal bridges occur where there is a break in the insulation layer, such as at junctions between different building elements or where there are penetrations through the insulation. These thermal bridges can lead to increased heat transfer, potentially causing energy inefficiency, discomfort, and increased energy costs.

The Psi-value analysis involves calculating the thermal transmittance of these thermal bridges to understand their impact on the overall energy performance of a building. This analysis considers factors such as the geometry of the building elements, material properties, and the surrounding environmental conditions. The goal is to identify and quantify the heat flow through these thermal bridges.

By understanding the Psi-values of different building components, architects and engineers can make informed decisions to improve the thermal performance of a building. This may involve optimising the design, using better insulating materials, or implementing specific construction details to minimise thermal bridging and enhance overall energy efficiency.

At The Wright Consultancy we specialise in bespoke Psi-Value calculations and reporting for any size of project. If you would like to know more, please connect with us:

Connect Today

We want to know you, your company and your analysis needs.
The best way we can do this is to talk with you directly and understand how we can help.

Scroll to Top