What the BRUKL Report Shows
BRUKL stands for Building Regulations UK Part L. The report checks the proposed design against a notional building of the same size and shape:
- Criterion 1: the building emission rate (BER) and primary energy rate (BPER) must be no worse than the target emission rate (TER) and target primary energy rate (TPER).
- Criterion 2: the fabric and building services must meet the limiting standards: U-values, air permeability, plant efficiencies and controls.
A BRUKL can pass the targets and still fail on a single element, so both sections matter.
Design Stage and As Built
Building control needs the BRUKL twice. The design stage report goes in before work starts. The as-built report follows at completion, updated with the final specification and the measured air permeability, and the non-domestic EPC is produced from that as-built model.
If a design stage BRUKL fails, the model shows which criterion fails and by how much. Changes to fabric, glazing, plant efficiency or renewables can then be tested in the model before the drawings are fixed.
SBEM or Dynamic Simulation?
SBEM is the standard route and suits most non-domestic buildings. Dynamic simulation modelling is an approved alternative that produces the same BRUKL report, and is the better choice for buildings with exposed thermal mass, natural or mixed-mode ventilation, atria or plant that SBEM cannot represent. We produce BRUKL reports in IES VE using either method. See SAP vs SBEM vs DSM for how the methods compare, or our Part L2 BRUKL and EPC service.
Last reviewed: November 2026
