Commercial Part L Compliance


All new buildings, domestic and commercial must comply with Part L of the building regulations. This new single method of compliance replaces the multiple compliance routes set out in 2002, but does however, allow some flexibility to the designer in choosing to improve combinations of the building fabric, plant efficiency and consideration of renewable schemes.

Building Regulations Part L2A & L2B ensures the proposed development/extension shall meet the minimum standards set by Office of the Deputy Prime Minister (ODPM).

For non-domestic buildings, compliance can be demonstrated using the Simplified Building Energy Model (SBEM) calculation tool or through active simulation using approved Dynamic Simulation Modelling (DSM) software. As the names suggest, SBEM is a simplified tool capable of assessing compliance only and cannot be used as a design tool due to these limitations, whereas the DSM method allows for designs to be assessed for in far more detail, and generally reports more accurate figures.

GreenFish Consulting are well versed in both compliance methodologies, utilising the DSM method where additional thermal modelling and building analysis services are required.

There are 5 components to Part L2A compliance

  • Achieving The Building Emission Rate (BER)
  • Limits on Design Flexibility
  • Limiting Solar Gains
  • Building Performance Consistent With BER
  • Provisions For Energy Efficient Operation of the Building

There are two stages to Part L Compliance design stage and as-built stage.

Design stage
Needs to be completed and submitted to your Building Control Body or Approved Inspector at the same time as your Building Control Application.

As-built stage
This happens when the build is complete and a Certificate of Compliance will need to be produced and issued to the building control. This takes into account any changes from the design assessment and also specific details that were unavailable at design stage, such as the air pressure test result. GreenFish consulting offer a complete service from Design through to As Built, and will conduct new analyses as and when changes are made, in order to ensure that the As Built assessment still meets the compliance criteria.

It is often the case that additional compliance targets must be met to achieve compliance, such as a certain of the buildings demand being met by renewable technologies, or specific regulations being met such as BB101 for Schools. GreenFish consulting offer a vast array of services and can offer a bespoke ‘all in’ price at the start of the project, reducing uncertainty and allowing for changes to be made without incurring additional re-simulation costs.


To view the Department for Communities and Local Government L2A requirements click here.

To view the Department for Communities and Local Government L2B requirements click here.

Contact us about Commercial Part L Compliance