L2B SBEM Calculations
SBEM calculations for commercial conversions, extensions, alterations and changes of use, helping demonstrate Building Regulations compliance and support production of the final commercial Energy Performance Certificate.
SBEM Calculations for Commercial Conversions and Alterations
L2B SBEM calculations are used for many projects involving existing non-domestic buildings. This can include commercial conversions, changes of use, extensions, major alterations and the refurbishment of offices, shops, warehouses, hotels and other commercial premises.
The assessment considers the retained building fabric together with proposed upgrades, newly constructed elements, heating, cooling, ventilation, hot water, lighting and renewable technologies.
One Stop Consult coordinates accredited commercial energy assessors who can complete the required calculations, identify areas of non-compliance and advise on practical improvements to the proposed design.
When Are L2B SBEM Calculations Required?
SBEM calculations may be required where an existing commercial building is altered, extended, refurbished or changed to a different non-domestic use.
Commercial Conversions
Existing buildings converted into offices, retail, industrial, leisure, healthcare or other non-domestic accommodation.
Changes of Use
Buildings changing from one commercial use to another where energy compliance must be demonstrated.
Commercial Extensions
New extensions added to existing offices, warehouses, shops, schools or other non-domestic buildings.
Major Refurbishments
Projects involving substantial upgrades to the fabric, glazing, heating, cooling, ventilation or lighting.
Shell and Core Fit-Outs
Existing shells completed or reconfigured for new commercial occupiers and activities.
Mixed-Use Alterations
Existing developments where commercial areas are altered, subdivided or assigned new uses.
Existing and Proposed Building Performance
L2B assessments require a clear record of what is retained, upgraded, removed or newly installed.
Existing Building Fabric
Existing walls, floors, roofs, windows, doors and other retained elements are reviewed using available evidence.
Proposed Thermal Upgrades
New insulation, replacement glazing and improvements to retained construction are incorporated into the model.
New Extensions and Elements
Newly constructed walls, roofs, floors and openings are assessed using their proposed design specifications.
Updated Building Services
New or retained heating, cooling, ventilation, hot water, lighting and controls are included within the assessment.
What Is Assessed in an L2B SBEM Calculation?
The assessment models the energy performance of the proposed commercial space using the available information for the existing building and planned alterations.
Accurate existing and proposed plans are important because the assessor must understand room uses, building zones, retained construction and the systems serving each area.
Building Zoning and Changes of Use
Commercial buildings are divided into zones based on activity, occupancy, conditioning and building-services arrangements. Alterations and changes of use can significantly affect these zones.
A warehouse converted into offices, for example, may introduce greater heating, cooling, ventilation and lighting demand than the previous use.
Clear room-use information and coordinated mechanical and electrical drawings help the assessor model each area correctly.
Retained Construction and Thermal Upgrades
Existing commercial buildings often combine older construction with new insulation, glazing and extension elements.
Existing External Walls
Solid, cavity, framed, cladded or other retained wall constructions are assessed using the available evidence.
Roof Upgrades
Existing pitched, flat or metal-deck roofs can be modelled with proposed insulation improvements.
Floor Construction
Existing and proposed ground floors, suspended floors and floors over unheated spaces are considered.
Windows and Curtain Walling
Retained and replacement glazing is assessed using thermal and solar-performance information.
Extension Elements
New walls, floors, roofs, windows and doors are included using their intended construction specification.
Thermal Continuity
Junctions between retained and new construction should be coordinated to reduce avoidable heat loss.
Heating, Cooling, Ventilation and Lighting
Changes to building use often require significant upgrades to the mechanical, electrical and lighting systems.
Heating Systems
Existing or proposed boilers, heat pumps, district systems and controls are assessed according to their efficiency.
Cooling Systems
Air-conditioning and comfort-cooling systems are modelled according to their performance, zoning and controls.
Ventilation
Natural ventilation, mechanical ventilation, heat recovery and fan energy are included.
Hot Water
Water-heating plant, storage, distribution and controls are assessed where relevant to the proposed use.
Lighting
Installed lighting power and occupancy or daylight controls can have a substantial effect on the calculation.
Building Controls
Zoning, sensors, time controls and building-management systems can support improved energy performance.
Common Issues Affecting L2B SBEM Compliance
Existing commercial buildings can present practical constraints that should be considered early in the design.
Unknown Existing Construction
Limited evidence for walls, roofs and floors can lead to conservative assumptions.
Large Glazed Areas
Shopfronts, curtain walling and rooflights can increase heat loss, solar gains and cooling demand.
Inefficient Retained Plant
Existing heating, cooling or ventilation systems may perform poorly compared with current standards.
Change in Occupancy
A more intensive use may increase lighting, ventilation, heating, hot-water and cooling requirements.
Limited Space for Upgrades
Existing structure, floor levels, façades or ceiling voids can restrict insulation and service improvements.
Incomplete Services Design
Missing plant, lighting or ventilation information can delay the assessment or require assumptions.
Improving an L2B SBEM Result
Where the initial proposal does not achieve the required performance, the model can be reviewed to identify targeted improvements.
Upgrade the Building Fabric
Improve retained walls, roofs, floors, windows or doors where technically and commercially practical.
Review Glazing and Solar Gain
Improve glazing performance or introduce shading to reduce cooling demand and heat loss.
Upgrade Heating and Cooling
Replace inefficient plant or improve system controls, zoning and distribution.
Improve Ventilation Efficiency
Reduce fan power, introduce heat recovery or refine the proposed ventilation strategy.
Improve Lighting Performance
Reduce installed lighting power and add occupancy or daylight controls.
Add Renewable Technology
Introduce solar PV or other suitable low-carbon measures where appropriate.
How the L2B SBEM Process Works
The assessment should begin while the proposed fabric and building-services specification can still be adjusted.
Project Review
Establish the existing use, proposed use, altered areas and current project stage.
Information Assessment
Review the building fabric, room uses and mechanical, electrical and lighting proposals.
SBEM Modelling
Model the proposed commercial spaces using approved software and suitable zoning.
Compliance Advice
Identify fabric, services, lighting, control or renewable improvements where required.
Final Documentation
Update the model using final information and support production of the commercial EPC.
Information Required for a Quotation
Provide the full project address, existing and proposed building uses, approximate floor area and current design or construction stage.
Please also send the latest existing and proposed plans, elevations and sections, together with any available construction, heating, cooling, ventilation and lighting information.
Information Needed for the Final Assessment
The completed calculation should reflect the building as actually altered and the systems finally installed.
Final Construction Build-Ups
Confirmation of retained and upgraded walls, floors, roofs and insulation.
Glazing Information
Final specifications and performance data for retained or replacement windows, doors and curtain walling.
Heating and Cooling Plant
Manufacturer and model information for systems, efficiencies and controls actually installed.
Ventilation Information
Final fan, air-handling, heat-recovery and commissioning details where applicable.
Lighting and Controls
Final lighting power, luminaire information and occupancy or daylight controls.
Changes From the Design
Details of substituted products, revised layouts or altered building-services specifications.
L2B SBEM Calculations for a Range of Existing Buildings
Assessments can be coordinated for individual units, whole buildings and larger mixed-use refurbishment schemes.
Nationwide L2B SBEM Calculation Service
One Stop Consult coordinates SBEM calculations for existing non-domestic buildings throughout mainland UK. Assessments can be provided for conversions, refurbishments, extensions, changes of use, fit-outs and major commercial alterations.
Other Services Your Project May Require
L2B SBEM calculations are commonly coordinated alongside commercial certification, testing and design services.
Important L2B SBEM Information
SBEM compliance depends on the applicable Building Regulations, existing construction, proposed alterations, building use, zoning, installed systems and evidence available. Conservative assumptions may be required where the existing fabric or plant cannot be verified. The assessment should be completed before work progresses too far so that any required changes can be incorporated efficiently. One Stop Consult provides consultancy and coordination support through its specialist accredited commercial energy-assessor network.
L2B SBEM Calculation FAQs
What is an L2B SBEM calculation?
It is an energy-performance assessment used for many alterations, conversions, extensions and changes of use involving existing non-domestic buildings.
How is L2B different from L2A?
L2A applies to new non-domestic buildings, while L2B relates to existing commercial buildings undergoing certain alterations, extensions or changes of use.
Do I need an SBEM calculation for a commercial change of use?
It may be required depending on the existing use, proposed use, extent of work and applicable Building Control requirements.
Do you need existing drawings?
Existing and proposed drawings are highly beneficial because the assessor must identify retained, upgraded and newly formed areas.
What happens if the proposed design does not comply?
The assessor can review the model and recommend practical improvements to the fabric, glazing, heating, cooling, ventilation, lighting or renewable-energy strategy.
Can existing construction be assessed if it is unknown?
Suitable evidence should be provided wherever possible. Conservative assumptions may be required where construction details cannot be verified.
Does an L2B SBEM include the commercial EPC?
The EPC can normally be produced after the final SBEM assessment has been completed and the necessary completion information has been received.
Is an air test always required for an existing building?
Not necessarily. The requirement depends on the project scope, applicable regulations and Building Control requirements.
Do you provide L2B SBEM calculations nationwide?
Yes. We coordinate suitable accredited assessors for eligible non-domestic projects throughout mainland UK.
Request Your Free L2B SBEM Calculation Quote
Complete the form below with the project address, existing and proposed building uses, approximate floor area and current project stage. Upload the latest existing and proposed drawings and any available construction, mechanical, electrical and lighting information so our team can review the project and coordinate an appropriate quotation.