When it comes to Energy Performance Certificates (EPCs) in the UK, not all assessments are created equal. The type of building—residential or commercial—dictates which methodology is used: SAP (Standard Assessment Procedure) for dwellings and SBEM (Simplified Building Energy Model) for non-domestic spaces.
While both systems aim to assess a building’s energy efficiency, their underlying methodologies differ significantly in data inputs, calculation scope, and intent. In this article, we’ll unpack the core differences between SAP and SBEM methodologies, and why understanding them matters for property owners, landlords, and developers.
🔍 What Is SAP and When Is It Used?
SAP is the methodology used for producing EPCs for:
Houses
Flats
Maisonettes
Residential new builds or conversions
Key Purpose: To assess energy efficiency based on how a property is built and heated, using standardised assumptions for occupancy, climate, and energy use.
SAP assessments are regulated by BRE (Building Research Establishment) and follow government-approved software like Elmhurst or Stroma.
Core SAP Inputs Include:
U-values of walls, roof, and floors
Window types and glazing
Heating system type and controls
Hot water system efficiency
Low-energy lighting percentage
Renewable systems (e.g., solar PV, heat pumps)
🟩 Result: An EPC rating from A to G with estimated running costs and CO₂ emissions.
👉 Learn how our London-based assessors perform SAP-based EPCs
🏢 What Is SBEM and When Is It Used?
SBEM is used for commercial or non-dwelling buildings such as:
Offices
Warehouses
Retail shops
Schools and healthcare facilities
Hotels and restaurants
Key Purpose: To assess actual operational energy performance based on building usage, zones, hours of operation, and system complexity.
SBEM calculations are often performed using iSBEM or commercial tools like DesignBuilder.
Core SBEM Inputs Include:
Internal zoning by activity (e.g., office vs lobby)
HVAC systems and their controls
Lighting system and occupancy sensors
Building fabric and construction
Operating hours and schedules
Mechanical ventilation and cooling loads
🟧 Result: A non-domestic EPC with a calculated CO₂ emission rate and a rating from A to G.
⚙️ Methodology Differences at a Glance
| Category | SAP (Residential EPC) | SBEM (Commercial EPC) |
|---|---|---|
| Property Type | Houses, flats, residential units | Shops, offices, schools, factories, etc. |
| Assumptions | Standardised (fixed occupancy, usage) | Tailored to actual usage and operating hours |
| Complexity | Simpler input structure | Highly detailed and zone-specific |
| Energy Use Focus | Fabric, heating, lighting | HVAC, lighting, zoning, and operational profile |
| Software Tools | SAP 10, Elmhurst, Stroma | iSBEM, DesignBuilder, G-iSBEM |
| Assessment Time | 1–2 hours (average) | 3–6 hours or more, depending on complexity |
| Ideal For | Homeowners, landlords, builders | Facility managers, commercial property owners |
💬 Why These Differences Matter
Accuracy vs Consistency
SAP prioritises consistency across all homes, even if it doesn’t reflect real-life usage.
SBEM allows customisation by building function, offering a more dynamic (but less standardised) picture.
Upgrade Recommendations
Residential EPCs may suggest simple upgrades like loft insulation or new boilers.
Commercial EPCs may involve HVAC system optimisation, lighting redesign, or control strategies.
Regulatory Compliance
Different MEES (Minimum Energy Efficiency Standards) apply to residential and commercial EPCs.
Knowing the methodology helps ensure upgrades meet legal thresholds.
For MEES updates or EPC advice tailored to your property type, reach out via our Contact Us page.
🗓️ Booking the Right EPC with EPCrate
Whether you need a domestic SAP assessment or a commercial SBEM calculation, our certified team at EPCrate.co.uk offers expert guidance and fast turnaround.
✅ Book your EPC now
💷 See pricing for residential, commercial, and same-day appointments
📍 Available across London and Greater London boroughs
Still unsure which EPC applies to your building?
Let our expert assessors guide you—get in touch today.
