BPE Packages

SAP Calculations

SAP calculations (Standard Assessment Procedure) are the UK government’s methodology for measuring energy efficiency & CO2 emission rates for new builds, extended, or converted residential dwellings. They should be submitted to Building Control to ensure compliance with Building Regulations Part L. 


Part L1a – SAP assessment is carried out before the start of site works for submission to Building Control. Upon completion, an ‘As Built’ SAP calculation is completed. 


Part L1b – For converted buildings, SAP calculations are required to assess the thermal performance of the building fabric, along with the energy requirements of the heating, lighting, and hot water systems. 

SBEM Calculations

Our team of Veritherm Energy assessors are experienced in producing SBEM (Simplified Building Energy Model) & DSM (Dynamic Simulation Model) modelling across a variety of non-domestic buildings including schools, hospitals, offices, industrial and commercial buildings. 


SBEM Assessment – Carried out at design stage before construction. ‘As Built’ SBEM calculations are then completed alongside a final air test to issue final EPC. 


DSM – Thermal modelling is carried out to assess the environmental performance of buildings, including real-time data, historical weather & accurate sun path analysis.

U-Value Calculations

Veritherm provides U-value calculations to assist with Building regulations/Standards compliance. Particularly important for extensions to properties. 



Where compliance is required for a whole building energy performance (new building). U-values are used within SAP calculations for new dwellings & also SBEM calculations for new non-dwellings. However, for some extensions, U-value calculations should be obtained for compliance. 

Psi – Value Calculations

Veritherm provide bespoke PSI Value calculations using specialist thermal modelling software. 


PSI Values are used to calculate a buildings overall heat loss at a junction (thermal bridging). Thermal bridges can have significantly higher heat transfer than the surrounding materials & occurs where two thermal elements meet. 


If an SAP or SBEM assessment of a property is required, then the PSI value needs to be obtained. This can be a default measurement and may affect whether the property complies with regulations. 


Building regulations stipulate that all SAP & SBEM assessments must include a thermal bridge figure and is especially important if higher levels of sustainability are to be achieved. 

Daylight Calculations

Measuring daylight efficiency is part of the requirement for both BREEAM & the code for Sustainable Homes. 

Verithrem’s daylight and sunlight assessments are helping clients analyse existing and expected levels of daylight and sunlight. Our reports can help demonstrate measures to reduce potential impacts on proposed developments. 

We can also help during the design process to control solar heat gain and achieve sufficient light levels to comply with Part L of Building Regulations.