Part L and EPC for Commercial Offices in 2026

Part L scope

Part L (Conservation of fuel and power) sets minimum energy performance standards for new construction and major refurbishment. For commercial offices, the relevant document is Approved Document L2A (new) and L2B (existing).

2022 edition changes

• Target CO₂ emissions reduced 27% vs 2013 edition
• Stronger fabric U-value requirements
• Enhanced MV/AHU efficiency requirements
• LED lighting effectively mandated (Luminous efficacy ≥ 95 lm/W)
• New measures for commissioning and handover

EPC — how it's calculated

EPC Rating (A–G) derived from the building's Simulated Energy Performance Index (SEPI). Calculated using:

• SBEM (Simplified Building Energy Model) for most commercial
• DSM (Dynamic Simulation Modelling) for complex buildings
• Approved software (DesignBuilder, iSBEM, Sefaira)

Typical London commercial EPC distribution Q1 2026

• Grade A modern: B/C (compliant)
• Grade B refurbished: C/D (variable)
• Grade B unrefurbished: D/E (MEES compliant but borderline)
• Period / listed: D/E/F (compliance-challenged)

What we do

EPC-uplift-by-design through LED, DALI, HVAC recommissioning and fabric upgrades. See Lighting & Electrical, Office Fit-Out, MEES compliance article.

FAQs