Which Method Does Your Project Need?
How the Methods Differ
SAP (the Standard Assessment Procedure) covers dwellings only. It calculates energy use for heating, hot water, lighting and ventilation for the home as a whole, and checks the dwelling emission rate, primary energy rate and fabric energy efficiency against their targets. We run SAP in Elmhurst as an OCDEA.
SBEM (the Simplified Building Energy Model) covers non-domestic buildings. It works zone by zone with standard activity profiles, on a monthly basis, and checks the building emission rate and primary energy rate against the targets along with the limiting fabric and services standards.
DSM covers the same non-domestic buildings as SBEM, using approved software such as IES VE. It calculates hour by hour, so it represents thermal mass, natural and mixed-mode ventilation, glazing and complex controls more closely. The result is still a BRUKL report, checked against the same criteria.
SBEM or DSM?
For a non-domestic building, either route is accepted. SBEM is quicker and suits straightforward buildings. DSM is the better choice where the building relies on features a monthly method represents poorly, or where a dynamic model is needed anyway for overheating (TM52, BB101), operational energy (TM54) or BREEAM. If the dynamic model exists, using it for Part L avoids building a second model.
Mixed-Use Schemes
A building with flats above commercial units needs both methods: SAP for each dwelling and SBEM or DSM for the non-domestic parts, with the communal and commercial areas assessed on the non-domestic side. Planning energy statements usually need the results combined across the whole site, so it helps to have both calculations from one consultant. Contact us with the drawings and we will confirm how the scheme splits before any modelling starts.
Last reviewed: November 2026
