Part L2A (SBEM Calculation) compliance is a requirement for all new buildings and large extensions (to qualify as a large extension it needs to be both greater than 100m2 and greater than 25% of the existing building).

If the building does not qualify as a large extension then it should follow the guidance in Part L2B of the regulations.


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To ensure that the building complies with Part L2A regulations it needs to satisfy the following 5 criterion.

  1. Buildings should be designed and constructed to conserve fuels and power so as to minimise CO2 emissions related to the building’s operation.
  2. Buildings should be designed and constructed to minimise heat loss and heat gain through the building fabric and building services distribution.
  3. Buildings should be designed and constructed to avoid excessive solar gain and to reduce requirements for artificial cooling.
  4. It must be demonstrated that the requirements have been met though approved calculation methodologies, pressure tests and results of testing and commissioning.
  5. Appropriate operation and maintenance manuals are required so that no more carbon emissions than are reasonable occur in use.

All aspects of the building design can affect the Part L2 compliance of the building. This includes:

  • The building constructions and U-values
  • Boiler efficiencies and air conditioning co-efficient of performance
  • Building envelope air tightness
  • Lighting efficiency and controls
  • Fan and pump efficiencies
  • Heat recovery efficiencies
  • Any renewable or low carbon technologies installed

Although there is some design flexibility on what services are installed and their efficiencies, any services used will need to meet minimum standards set out in the Non-Domestic Compliance Guide.


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How we can Help

At EEABS we will work with you to ensure that your buildings intended services will comply with the minimum standards and that your buildings overall carbon emissions will achieve an SBEM calculation that passes and therefore satisfies the current Part L2 building regulations.

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All our engineers at EEABS are registered Low Carbon Consultants. Set up by CIBSE and The Carbon Trust, the Low Carbon Consultant register can only be joined by consultants who have proven competence in the energy efficient design and operation of buildings.

We are also CIBSE Certified Low Carbon energy Assessors. CIBSE only registers experienced professionals as Energy Assessors, while other bodies will accredit assessors on completion of a short course. CIBSE also carry out regular compliance checks on our work ensuring that we offer nothing but the most accurate Part L2 reports (SBEM Calculations) and Energy Performance Certificates

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