When it comes to building regulations and energy efficiency standards in the UK, two terms often come up: SAP calculations and Non-Residential Energy Performance Certificates (EPCs). These assessments play a crucial role in both residential and commercial construction projects, ensuring compliance with building regulations and supporting efforts to reduce carbon emissions.
In this blog, we’ll break down what SAP calculations are, how they differ from non-residential EPCs, and why both are important for developers, landlords, and property owners.
What Are SAP Calculations?
Standard Assessment Procedure calculations are the UK government’s approved method for assessing the energy performance of residential buildings. They are required for:
New-build homes
Conversions (e.g. commercial to residential)
Extensions with significant glazing
SAP assessments measure how much energy a dwelling will use for heating, hot water, lighting, and ventilation, and how much carbon dioxide it will emit as a result. The results of SAP calculations contribute to the Energy Performance Certificate (EPC) issued for the property.
Key Elements Considered in SAP Calculations:
Thermal insulation of walls, roofs, and floors
Heating system type and efficiency
Renewable technologies (solar panels, heat pumps)
Window types and glazing ratios
Air tightness and ventilation
When Are SAP Calculations Required?
At design stage – to demonstrate that the building will meet Part L of the Building Regulations (energy efficiency)
At completion – to issue the final EPC and confirm compliance
What Are Non-Residential EPCs?
While SAP is used for dwellings, non-residential EPCs assess the energy performance of commercial and public buildings. This includes:
Offices
Retail units
Warehouses
Restaurants
Hotels
Public buildings over 250 m²
These EPCs are produced using the SBEM (Simplified Building Energy Model) or DSM (Dynamic Simulation Modelling) methodology, depending on the complexity of the building.
What Is Included in a Non-Residential EPC?
Building fabric and insulation levels
Lighting systems
Heating, ventilation, and air conditioning (HVAC)
Use of renewable energy sources
Building orientation and glazing
Once assessed, the property receives an energy efficiency rating from A (most efficient) to G (least efficient). A valid EPC is a legal requirement when a commercial building is sold, rented, or constructed.
Key Differences: SAP vs. Non-Residential EPC
| Feature | SAP Calculations | Non-Residential EPC |
|---|---|---|
| Applicable To | Residential buildings | Commercial/public buildings |
| Assessment Method | SAP methodology | SBEM or DSM |
| Required At | New builds, conversions, large extensions | Sale, rent, or new-build completion |
| Output | SAP score & EPC for dwellings | EPC for non-dwellings |
| Compliance Target | Part L (residential) | Part L2 (non-residential) |
Why These Assessments Matter
Legal Compliance: Avoid penalties by ensuring all construction or property transactions have the required documentation.
Energy Efficiency: SAP and EPC ratings help reduce operational costs and improve the environmental footprint.
Marketability: Properties with higher EPC ratings are more attractive to buyers and tenants.
Sustainability Goals: Contributing to national efforts to reduce carbon emissions and improve building efficiency.
Need Help with SAP Calculations or a Non-Residential EPC?
Whether you’re a developer working on new housing or a business owner preparing to lease commercial space, ensuring you have the right assessments is crucial. Our qualified energy assessors provide accurate SAP calculations and non-domestic EPCs to keep your project compliant and efficient.
