L2A SBEM Calculations
Design-stage and as-built SBEM calculations for new commercial and non-domestic buildings, helping demonstrate Building Regulations compliance and support production of the final Energy Performance Certificate.
SBEM Calculations for New Commercial Buildings
SBEM calculations assess the predicted energy performance of new non-domestic buildings. The model considers the building fabric, heating, cooling, hot water, ventilation, lighting and renewable technologies to determine whether the proposed development satisfies the relevant Part L requirements.
The process normally takes place in two stages. A design-stage SBEM is completed before construction, followed by an as-built assessment once the building has been completed and the final specification is known.
One Stop Consult coordinates accredited commercial energy assessors who can complete the calculations, identify compliance shortfalls and advise on practical improvements to the proposed design.
When Are L2A SBEM Calculations Required?
SBEM calculations are generally required for newly constructed non-domestic buildings and many new commercial developments.
New Offices
Standalone offices and office accommodation within larger commercial developments.
Retail Buildings
Shops, retail parks, supermarkets, showrooms and customer-facing commercial premises.
Industrial and Warehouse Units
Factories, workshops, warehouses, logistics units and distribution buildings.
Schools and Public Buildings
Education, healthcare, community and other publicly accessible non-domestic buildings.
Hotels and Leisure Buildings
Hotels, gyms, leisure centres, restaurants and similar commercial accommodation.
Mixed-Use Developments
Non-domestic areas within mixed-use schemes where separate SBEM assessment is required.
Design-Stage and As-Built SBEM Calculations
New non-domestic buildings are normally assessed at both design and completion stages.
Design-Stage SBEM
The proposed building is modelled before construction to establish whether the design is capable of satisfying the required energy and carbon targets.
Building Regulations Submission
The design-stage report provides Building Control with evidence of the intended Part L compliance strategy.
As-Built SBEM
The calculation is updated at completion using the final construction, systems, airtightness result and any design changes.
Final EPC
Once the as-built information is complete and the building achieves compliance, the final commercial EPC can be lodged.
What Is Assessed in an SBEM Calculation?
SBEM models the predicted energy consumption and carbon performance of the building across its different activity zones.
Accurate architectural and building-services information is essential because occupancy patterns, lighting, heating, cooling and ventilation requirements can vary between areas.
Building Zoning and Activity Areas
Commercial buildings are divided into zones based on their use, occupancy, conditioning and building-services arrangements. An office, meeting room, warehouse, kitchen and circulation space may each require different assumptions within the model.
Correct zoning is important because each area can have different heating, cooling, ventilation, lighting and occupancy profiles.
Clear room uses and coordinated mechanical and electrical layouts help the assessor create a more accurate and reliable model.
How L2A SBEM Compliance Is Demonstrated
The proposed building is compared against a notional building created using the approved assessment methodology.
Building Emission Rate
The calculated carbon emissions of the proposed building are compared with the applicable Target Emission Rate.
Primary Energy
The assessment considers the primary energy associated with the fuels and systems used by the proposed building.
Fabric Performance
Walls, floors, roofs, windows and doors must satisfy the applicable limiting standards.
Building Services
Heating, cooling, ventilation, hot water, lighting and controls must meet relevant minimum-efficiency requirements.
Solar Gains
The design is reviewed for excessive solar gains and the effect of glazing, shading and cooling demand.
Consistency of Evidence
The calculation should reflect the drawings, specifications and products intended for construction.
Thermal Performance of the Building Envelope
The efficiency of the building fabric has a major influence on heating, cooling and overall energy demand.
External Walls
Wall build-ups, insulation thicknesses and U-values are modelled according to the proposed construction.
Ground and Exposed Floors
Floors are assessed according to their construction, perimeter and relationship with external or unheated spaces.
Roofs
Pitched, flat, metal-deck and other roof systems are included using their proposed thermal specification.
Glazing and Doors
U-values, solar performance, frame factors and areas of windows, curtain walling, rooflights and doors are assessed.
Thermal Bridging
Junction details and thermal-bridging assumptions influence heat loss through the building envelope.
Airtightness
The proposed design air-permeability target is included at design stage and replaced with the measured result at completion.
Heating, Cooling, Ventilation and Lighting
Building services often have the greatest effect on commercial energy use and SBEM performance.
Heating Systems
Boilers, heat pumps, district systems and other heating plant are assessed using their efficiency and control arrangements.
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 within the assessment.
Hot Water
Water-heating systems, storage, distribution and controls are assessed where relevant to the building use.
Lighting
Installed lighting power, occupancy controls, daylight controls and display lighting can significantly affect the result.
Controls and Management
Time controls, zoning, sensors and building-management systems can improve efficiency when accurately specified.
Renewable and Low-Carbon Technologies
Renewable technologies can help reduce the calculated carbon and primary-energy performance of a new commercial building.
Solar photovoltaic panels are commonly included, while heat pumps, heat-recovery systems and other low-carbon measures may also support the wider compliance strategy.
The suitability of each measure depends on the building use, roof area, orientation, electrical demand, planning constraints and project budget.
What Happens If the Design Does Not Comply?
A failing result can often be improved through targeted changes rather than a complete redesign.
Improve the Building Fabric
Upgrade selected walls, floors, roofs, windows or doors to reduce heat loss.
Review Glazing and Solar Gain
Adjust glazing performance, shading or orientation to manage heat loss and cooling demand.
Upgrade Heating and Cooling
Specify more efficient plant, distribution systems and control strategies.
Improve Ventilation Efficiency
Reduce fan power, introduce heat recovery or refine the ventilation strategy where appropriate.
Improve Lighting Performance
Reduce lighting power and introduce effective occupancy and daylight controls.
Add Renewable Technology
Introduce or increase solar PV or other suitable low-carbon technologies.
How the L2A SBEM Process Works
The most efficient assessment process begins before construction, while the fabric and building-services specification can still be adjusted.
Design Review
Obtain the drawings, room uses, construction build-ups and proposed mechanical and electrical specification.
SBEM Modelling
Model the building geometry, zones, fabric and building services using approved software.
Compliance Review
Assess the proposed building against the applicable energy and carbon targets.
Design Advice
Recommend suitable fabric, services, controls or renewable improvements where required.
As-Built Assessment
Update the model using final information and support issue of the commercial EPC.
Information Required for a Quotation
Provide the full project address, proposed building use, floor area, current project stage and the latest architectural drawings.
Please also send any available construction specification, mechanical and electrical designs, lighting layouts, glazing information, ventilation strategy and renewable-energy proposals.
Information Needed for the As-Built SBEM
The final assessment must reflect the building as actually constructed and commissioned.
Final Construction Build-Ups
Confirmation of the materials, insulation and thicknesses installed within the walls, floors and roofs.
Air-Test Result
The measured air-permeability result for the completed building, where airtightness testing is required.
Heating and Cooling Plant
Manufacturer and model information for the 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, occupancy controls and daylight controls.
Renewable-Energy Details
Final capacity, orientation and product information for any solar PV or other low-carbon systems installed.
L2A SBEM Calculations for a Range of Buildings
Assessments can be coordinated for small commercial units, major developments and complex multi-zone buildings.
Nationwide New-Build SBEM Calculation Service
One Stop Consult coordinates design-stage and as-built SBEM calculations for new non-domestic buildings throughout mainland UK. Assessments can be provided for individual commercial units, industrial buildings, offices, schools, retail developments and larger mixed-use schemes.
Other Services Your Project May Require
SBEM calculations are commonly coordinated alongside testing, certification and wider commercial-building services.
Important SBEM Calculation Information
SBEM compliance depends on the applicable Building Regulations, building use, zoning, construction specification, installed systems and evidence provided. The design-stage assessment should be completed before construction so that any required changes can be incorporated early. The as-built result may change where products, systems or construction details differ from the approved design. One Stop Consult provides consultancy and coordination support through its specialist accredited commercial energy-assessor network.
L2A SBEM Calculation FAQs
What is an L2A SBEM calculation?
It is an energy-performance assessment used to demonstrate compliance for a new non-domestic building under the relevant commercial Part L requirements.
When should the design-stage SBEM be completed?
It should be completed before construction begins so the fabric, heating, cooling, ventilation and lighting specifications can be checked and amended where necessary.
What is the difference between design-stage and as-built SBEM?
The design-stage assessment models the proposed building. The as-built assessment is updated using the final construction, installed systems, airtightness result and any changes made during the works.
Which buildings need an SBEM calculation?
Most new non-domestic buildings require an assessment, subject to the building use, size, exemptions and applicable Building Regulations.
What happens if the building fails the SBEM calculation?
The assessor can review the model and recommend targeted improvements to the fabric, glazing, heating, cooling, ventilation, lighting, controls or renewable-energy strategy.
Is an air test required for the as-built SBEM?
New non-domestic buildings commonly require airtightness testing, and the measured result is normally entered into the as-built assessment where applicable.
Does the SBEM calculation include the EPC?
The commercial EPC can normally be produced after the as-built SBEM has been completed and all required final information has been received.
Can you help improve the commercial specification?
Yes. The model can be used to compare different fabric, building-services, lighting, controls and renewable-energy options to identify a practical route to compliance.
Do you provide new-build SBEM calculations nationwide?
Yes. We coordinate suitable accredited assessors for eligible non-domestic projects throughout mainland UK.
Request Your Free L2A SBEM Calculation Quote
Complete the form below with the project address, proposed building use, floor area and current design stage. Upload the latest plans, elevations, sections and any available construction, mechanical, electrical and lighting information so our team can review the project and coordinate an appropriate quotation.