Thermal Bridging Analysis

As accredited thermal modellers, we can produce bespoke PSI-value calculations to achieve an accurate, highly efficient, and cost-effective fabric performance for new-build developments.

The insulation envelope of any heated building should be designed and constructed to limit heat loss through thermal bridging. Furthermore, Section 6 and Part L of the building regulations also require thermal bridging to be taken into account as part of energy assessments. Whilst repeating thermal bridges are taken into account through U-value calculations, a separate PSI-value calculation is required to assess non-repeating thermal bridges. 

With thermal bridging accounting for up to 25% of fabric heat loss, we work closely with our design team colleagues to identify effective measures of limiting heat loss through thermal bridging; minimising the risk of condensation and mould growth. 

Local Authorities and Housing Associations

Within SAP and SBEM calculations, having bespoke PSI-values available to energy assessors will not only help to improve the dwelling (DER) or building (BER) emissions rating, it will also significantly reduce the space heating energy demand; a common funding requirement of most local authorities and housing associations who aim to achieve a higher level of sustainability for their social and affordable housing stock.

Contractors and Housebuilders

We have supported many leading building contractors by producing bespoke PSI-values for their preferred methods of construction. This process involves working closely with design and procurement teams to review various aspects of the building fabric from material specification to U-value performance resulting in a highly efficient and cost-effective fabric design. 

Architects and Planners

Clients who engage with us at concept design stage have the opportunity of utilising our in-house thermally modelled construction detail packages which, when applied through SAP and SBEM calculations, can deliver up to a 50% improvement in thermal bridging performance for a typical dwelling (when compared with accredited details). This service is particularly beneficial to architects and designers who are keen to establish an accurate energy strategy from the outset.

It is important to note that where bespoke calculations are not available, energy assessors can only referenced PSI-values by applying 'default' or ‘accredited' figures, this however will typically result in a poorer fabric performance creating a performance gap between the proposed design and actual performance of a dwelling or building.


MAST have a close working relationship with Carbon Futures.  We engage them on a range of residential projects where they work with us to develop robust SAP and energy strategies ensuring that we exceed the minimum standards.  They undertake energy and thermal modelling, provide Section 6 certification as well as EPC’s.  We value their input in undertaking options appraisals and value engineering exercises, with them adopting a thorough and professional approach, often working to tight timescales.  We look forward to working with them in the future and would be happy to recommend their services.

MAST Architects