SBEM (Simplified Building Energy Model) is the government-approved calculation methodology used to produce every non-domestic Energy Performance Certificate (NDEPC) in England, Wales and Northern Ireland. This guide explains how SBEM works, when it is required, what inputs the model uses, and how each input affects the final asset rating.
SBEM models a building's annual CO₂ emissions from regulated energy uses (heating, cooling, hot water, ventilation, lighting) and compares them to a notional building of identical geometry and use built to current Building Regulations. The ratio between the actual building and the notional building becomes the SBEM Asset Rating, which is then mapped to an A–G EPC band.
On sale, on grant or assignment of a lease, on completion of a new build (Part L2A compliance), and on major refurbishment of a non-domestic property. SBEM is also used to model measures inside our NDEAR (Non-Domestic Energy Advice Reports) and MEES compliance pathways.
External wall U-values, glazing U-values and g-values, roof insulation, air permeability and thermal bridging typically account for the largest swing in an SBEM asset rating for older commercial stock. Buildings with pre-1970s cavity walls or single-glazed metal frames start heavily penalised and gain the most from targeted fabric upgrades.
Heating plant type and seasonal efficiency, hot-water generation, mechanical ventilation SFP (specific fan power), lighting installed load and control strategy, and any low- or zero-carbon technology (solar PV, air-source heat pumps). LED re-lamping paired with modern presence and daylight controls is often the highest-payback measure in an SBEM model.
iSBEM is the standard input tool used for the vast majority of commercial EPCs (Levels 3 and 4). Complex or Level 5 buildings — atria, mixed-mode ventilation, complex HVAC — require DSM software (IES-VE, TAS, DesignBuilder) but produce the same government-approved SBEM output.
No. SBEM is the calculation engine; the Commercial EPC (NDEPC) is the certificate that is lodged on the EPC Register once the SBEM model has been built and rated. Every non-domestic EPC in England and Wales is produced from an underlying SBEM (or DSM) model.
For a lodged Commercial EPC, yes — the Non-Domestic Energy Assessor (NDEA) must measure the building, record fabric build-ups and photograph plant. For a modelling-only SBEM (design-stage Part L compliance, refurbishment feasibility, MEES scenario testing) we can work from drawings and specifications with no site visit required.
The SBEM asset rating is a robust regulated comparison against a notional benchmark building. Actual in-use energy will always differ because it depends on occupancy, tenant fit-out and hours of operation — that's the difference between an asset rating (SBEM) and an operational rating (DEC). SBEM is highly reliable for the purpose it was designed for: comparing buildings and modelling improvement measures on a like-for-like basis.
From £250 for a small unit (< 500 m²). Level 3 typically covers up to around 2,000 m² with straightforward services and is the level most South West commercial stock falls under. Larger buildings, mixed-use blocks or Level 5 DSM projects are individually quoted.
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