Part L2A of the Building Regulations concerns the conservation of energy and power in new commercial buildings. The guidance contains five criteria necessary for compliance:
- Criterion 1 – Achieving the Building Emission Rate (BER); conducted using SBEM or DSM.
- Criterion 2 - Limits on design flexibility; Minimum U-Value and system efficiencies, conducted using SBEM or DSM.
- Criterion 3 - Limiting the effects of solar gains; a primitive assessment of solar gains, conducted using SBEM or DSM.
- Criterion 4 – Building Performance Consistent with BER; air testing and commissioning of systems.
- Criterion 5 – Provision for energy efficient operation; providing information to the occupants to allow efficient use of the building.
Part L2A of the building regulations requires nearly all conditioned commercial buildings above 50m² floor area to be tested under the regulation. This involves assessing the energy efficiency performance using the more simplistic ‘Simplified Building Energy Model’ (SBEM), or the more complex ‘Dynamic Simulation Method’ (DSM) assessment method. Both methods output the ‘BRUKL’ document required by Building Control as a demonstration of compliance.
Both methods use the ‘National Calculation Method’ (NCM). This involves the establishing a ‘notional building’ within the simulation software -based on the same size and shape of building as that proposed, but with notional specifications for window sizing, plant efficiencies, lighting controls and the like. An ‘Actual building’ model is also created based upon the proposed specification. The assessment compares the CO2 emissions from the ‘actual building’ with those from the ‘notional building’ in order to assess whether the proposed design achieves the standard required.
Greenlite Energy Assessors are accredited to carry out both Level 4 SBEM & Level 5 DSM types of Part L compliance assessment.
For more information concerning which assessment is most appropriate for your needs, please refer to the other pages in this section.
To check if it is necessary that your building requires Part L2A compliance, see our FAQ section.
In respect of Criterion 3, note that the assessment of solar gains is not an overheating analysis. Maintaining suitable internal temperatures is a design issue which lies outside the remit of the building regulations. Please see our pages on Overheating Analysis for further discussion.