What This Requirement Covers
Approved Document L (Conservation of fuel and power) for non-domestic buildings sets carbon emission targets and fabric standards for new commercial, industrial, and public buildings. Compliance is demonstrated through the National Calculation Methodology (NCM) using approved software such as IES Virtual Environment, TAS, or the Simplified Building Energy Model (SBEM).
Key Requirements
Compliance Method
- The energy performance of the building is calculated using the NCM and compared against a notional building of the same size and shape
- The actual building's CO2 emissions (Building Emission Rate, BER) must not exceed the Target Emission Rate (TER)
- A BRUKL (Building Regulations UK Part L) output document is produced showing compliance
Fabric Standards
Limiting U-values for new non-domestic buildings
- Walls: 0.26 W/m²K
- Floors: 0.22 W/m²K
- Roofs: 0.18 W/m²K
- Windows and curtain walling: 1.6 W/m²K
- Vehicle access doors: 1.5 W/m²K
- Air permeability: 5 m³/(h.m²) at 50 Pa (or as used in the BRUKL calculation)
Building Services
- Heating, ventilation, air conditioning, lighting, and hot water systems must meet minimum efficiency standards
- Lighting: Maximum installed power density and automatic controls (occupancy sensing, daylight dimming) are required
- HVAC: Systems must be designed and commissioned to achieve the efficiency assumed in the NCM calculation
- Metering: Sub-metering of energy consumption by end-use (heating, cooling, lighting, small power) is required in larger buildings
Display Energy Certificates (DECs)
- Public buildings over 250 m² must display a Display Energy Certificate showing the building's actual energy consumption
- DECs are based on metered energy data and must be updated annually
- An Advisory Report recommending energy-saving measures accompanies the DEC
Practical Compliance Tips
- Engage an energy consultant at the design stage to run SBEM or dynamic simulation modelling and advise on compliance strategies
- Consider the building orientation, glazing ratio, and shading to minimise cooling loads
- Specify high-efficiency lighting (LED) with automatic controls as standard; lighting is often the largest energy consumer in commercial buildings
- Commission all building services to verify they are operating as designed; commissioning certificates are required for Building Control
- Air permeability testing is required for non-domestic buildings; plan for it in the construction programme
- Keep the BRUKL output document, air test results, and commissioning certificates for the building file
- Monitor actual energy consumption against the DEC prediction to identify underperformance and opportunities for improvement