Whilst repeating thermal bridges are accounted for in U-value calculations, a separate Psi-value calculation is required to assess non-repeating thermal bridges at all the external junctions within a building.
Utilising our knowledge in thermal modelling coupled with our experience in architecture and construction, we have produced three thermally modelled detail packages, based on timber frame construction, providing architects and developers a viable alternative to outdated and unsupported resources such as Accredited Construction Details.
All details come in a range of material build-ups to accurately account for heat loss, significantly improve thermal bridging, and help to minimise the performance gap. A key aim our detail packs, is to provide a comprehensive set of details, aligned to typical construction practices, utilising an optimised component specification, which marries performance with buildability and practicality.
Our packs are graded by thermal performance (Silver, Gold and Platinum) and include all common junction types listed in SAP. This resource is available to contractors, architects and designers who are seeking to achieve an enhanced ‘fabric first’ solution through improved thermal bridging and U-value performance. The details are particularly beneficial in reducing energy demand for space heating as well as carbon emissions, assisting with building regulation compliance under Section 6 (Energy) and Part L1A.
Each pack has been designed to reduce unwanted infiltration and heat loss in buildings. All detail have a corresponding Psi-value calculated in accordance with BR497 (2nd Edition), which can be used in SAP calculations, provided the key principles and component specification are followed.
Why calculate Psi-values?
- Junction heat loss is 20-30% of total building heat losses, which is significant. These losses are often underestimated contributing towards the significant ‘performance gap’ in new dwellings.
- Designers will be penalised for using ‘Default’ Psi-values which are significantly worse than the actual performance of the junction.
- Optimising and calculating Psi-values can lead to a significant improvement in the performance of individual junctions leading to a lower overall Y-value per dwelling, which makes achieving compliance much easier.
- Lower Psi-values can help to significantly reduce construction costs.
Carbon Futures Thermally Modelled Construction Details illustrate the reduction of unwanted infiltration in buildings and provide a Psi-value for each individual junction situation, which can be used in SAP calculations, provided the principles outlined on the drawing and any identified component specification is followed. No liability will be accepted for any omissions or inconsistency should the drawings be used for construction.