SBEM calculations are used to determine the thermal performance of new and existing commercial properties. They are the government-approved methodology and are used to produce the Energy Performance Certificate (EPC) and BRUKL Report to show compliance with UK Building Regulations Part L2 (where applicable).
We use Design Builder software for all of our SBEM/DSM calculations ensuring highly accurate results.
New Build Properties
All new build properties in the UK require SBEM calculations to ensure compliance with UK Building Regulations and to determine carbon emissions. A BRUKL Report will be issued at the design stage and again at completion (alongside an EPC), which is used by Building Control to confirm compliance with Part L.
Most properties will fall under level 3 and 4 calculations, however, some buildings are deemed too complex to be assessed using standard SBEM calculations. These are classed as Level 5 and require Dynamic Simulation Modelling (DSM).
The criteria for a property to require a level 5 DSM assessment are for the building to have one or more of the following:
- Ventilation with enhanced thermal coupling to the structure
- Automatic blind control
DSM can, however, be used to model level 3 or 4 properties and usually results in a better performing building due to increased accuracy in calculations.
Conversions and Extensions
SBEM calculations are required for larger commercial extensions and can offer greater design flexibility. Part L2 sets out design standards which will need to be met and an SBEM calculation is required where the extension is above a certain size or where the existing building has an area greater than 1000m2 and is either being extended or a fixed building service is being introduced or expanded.
Large extensions require an SBEM calculation where:
- The floor area is greater than 100m2
- The total useful floor area of the extension exceeds 25% of the existing building floor area
Where the two conditions above are me, Building Control will class the building as a new build and will require Part L2A to be followed, and more stringent targets to be met.
All existing buildings require an EPC to be sold or let legally in the UK, with a minimum rating of an E being required under the Minimum Energy Efficiency Standards (MEES) for a rental. SBEM calculations are undertaken following a physical survey of the building and the EPC is then produced.
Frequently Asked Questions
Ideally, SBEM calculations should always be carried out at the start of your project, prior to the specification being finalised and work starting on site. This means that any issues that arise can be ironed out prior to construction and changes can be made in a cost-efficient manner.
The calculations are then updated at completion to reflect the final building and the compliance documents and EPC is issued. The cost for carrying out the calculations in these two stages is no different leaving the calculations until the end of the build, however the risk is so much lower as it eliminates any nasty surprises.
When carrying out SBEM calculations at the end of the build, it can become very costly to fix any compliance issues.
A BRUKL Report (Building Regulations UK Part L) is the report which is produced by the SBEM calculation when assessing for Building Regulations compliance on a new build property. The report demonstrates compliance with Part L of Building Regulations.
The report shows if the building complies with carbon emissions, solar gain and the limiting standards for both fabric and building services. It is required by Building Control prior to starting works on site and then an updated version issued once building is completed.
- Carry out the SBEM calculation as early as possible – this is key to ensuring you gain compliance in a cost-effective manner and eliminates expensive surprises later in the build.
- Ensure you design the building with highly efficient lighting systems and controls – this has a significant effect on the compliance of a commercial building.
- Focus on airtightness and defining a solid airtightness layer. A good air tightness test can have a considerable effect on compliance and is a very cost-effective way of achieving it.
- Design your heating and cooling system carefully. Using renewable energy systems will boost the SBEM results and provide significant savings in annual running costs – if you plan on retaining the building this can provide a great saving annually or is a great selling point if you plan on selling or renting the property.