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SBEM Calculations

Also referred to as SBEM Calculations, BRUKL (Building Regulations Part L) Reports (or Output Documents as they are formally known as)  are usually requested by Building Control at both the design and completion stage of a commercial building new construction, conversion or extension.

BRUKL Reports are also required by BREEAM Assessors in order to verify the Building Energy Rating and permit the award of related credits. (for more info on BREEAM click here.)

Part L2A

New Construction

Part L2B


Part L2B



BRUKL Reports (also referred to as SBEM calculations or reports) can either be generated using SBEM (Simplified Building Energy Modelling) or for more complex buildings that take into consideration daylighting and seasonal variances, DSM (Dynamic Simulation Modelling).


To complete the necessary calculations and generate the relevant reports, we require some basic information about the building. A full list will be provided upon instruction.

This page deals with BRUKL Reports as requested by Building Control. More information on our BREEAM services can be found here.


We will require to you complete a simple form and provide some relevant supporting evidence (such as product brochures). We will only ask you to provide relevant information.


  • HVAC info – location/heat recovery, make/model etc.

  • Lighting loads (w/m2 @ 100 LUX, or, lumens/watts either per zone or average for building)

  • Hot water systems (storage tank make/model/size)

  • U-Values – walls, floors, roofs, glazing, doors

  • Plans and elevations – must include measurements (PDF only. Do not provide AutoCAD files)

  • General overview of mechanical ventilation – location, heat recovery, make/model etc

  • External elevations / conceptual drawings

  • Air test Certificate if >500m2 (or if <500m2 and permeability is being declared as less than 15)

  • (optional but helpful) Photographs of the project, during construction and upon completion


Note, for Shell and Core / Design Stage, as a minimum we require only floor plans and elevations to produce either an EPC or an SBEM report. However, any M&E specifications or U values that have been recommended (in the absence of any information provided) within the calculations should be implemented as a minimum during fit out.



All Non-Domestic buildings require SBEM calculations at both design and completion stage unless they would normally be exempt from Part L (and therefore Commercial EPC requirements). These would include:

  • Places of worship

  • Stand-alone units of less than 50m2

  • Listed buildings that are unable to comply with Part L due to planning restrictions

  • Temporary buildings with a planned lifecycle of less than 2 years

L2A - New Build


SBEM calculations are required where the extension part has a floor area greater than 25% of the floor area of the original building and a gross internal area greater than 100m2.

An SBEM will also be triggered if the glazing areas are greater than those shown in the table below, and if so then the calculations will need to show that the extension is as energy efficient (with the same, or lower carbon emissions) than the equivalent extension but with compliant glazing areas.

The calculations will only apply to the extension area but may take into consideration the existing buildings core services.

L2B - Extensions


Essentially all conversions to non-dwellings require an SBEM Calculation in order to comply with Part L2b of the Building Regulations (or a regional variant). A conversion typically occurs as a result of a ‘Material Change of Use’, where the purpose or use of the building is altered.

Some examples of what is considered a ‘Material Change of Use’ are provided by Building Regulations/Standards:

  • The building is used as a hotel or boarding houses where it was previously not

  • The building is used as an institution or school where previously it was not

  • The building is used as a public building where previously it was not

  • The building is used as a dwelling where previously it was not

L2B - Convesions
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