SAP Calculations & Residential Part L Compliance

The Two Stages of Residential Compliance

1. Design-Stage SAP Calculations

Before construction begins on site, building control requires a design-stage SAP assessment. This ensures your proposed building fabric, insulation choices, window specifications, and heating systems are mathematically on track to pass. Engaging Up Energy at this early blueprint stage prevents costly structural amendments later.

2. As-Built SAP & On-Construction EPCs

Upon physical completion of the building, an On-Construction Energy Performance Certificate (EPC) must be generated and logged to legally sign off the development.

💡 Need an EPC for an existing project? We can issue the final SAP EPC and building control sign-off documentation regardless of whether Up Energy or another assessor managed the initial design-stage modelling.

Note: SAP EPCs apply strictly to domestic properties under Approved Documents L1. If your development is a commercial or non-domestic building, it requires SBEM calculations under Part L2.

Precision U-Value Calculations

U-values measure the rate of heat loss through specific building elements (walls, roofs, floors, and glazing) and form the foundation of a successful SAP model. Detailed, verified proof of these figures is heavily audited by building control.

If your architectural team or material suppliers cannot provide verified figures, Up Energy can model custom U-value calculations for your project. Simply provide us with the precise layer-by-layer material specifications of your thermal elements, and we will calculate the exact thermal transmittance values to optimise your model.