Approved Document L Volume 2 (2021 Edition with 2023 Amendments) – Conservation of Fuel and Power in Buildings Other Than Dwellings
Approved Document L, Volume 2: Buildings other than dwellings provides statutory guidance on complying with the energy efficiency requirements of the Building Regulations 2010 in England. Issued by the Department for Levelling Up, Housing and Communities, this document specifically addresses the conservation of fuel and power through Requirement L1 and the on-site generation of electricity under Requirement L2. This 2021 edition incorporates the 2023 amendments, which notably removed the primary energy factor as a performance standard for buildings connected to district heat networks.
The regulatory scope encompasses new non-domestic buildings, extensions, and various types of building work in existing premises, including renovations of thermal elements and material changes of use. The document establishes concrete performance metrics, requiring that the Building Primary Energy Rate and the Building Emission Rate do not exceed the targets set by the Simplified Building Energy Model (SBEM) or other approved software. It provides detailed technical standards for building fabric, including limiting U-values, airtightness thresholds, and solar gain limits, alongside minimum efficiency requirements for fixed building services such as heating, cooling, ventilation, and lighting.
Professional users must refer to the structured sections covering calculation methodologies, system-specific guidance, and commissioning procedures. The document also details mandatory notification requirements to Building Control Bodies and the provision of energy performance information to building owners through standardized BRUKL reports and building log books.
Energy Performance Calculations and Targets
New buildings must meet minimum standards of total energy performance evaluated by comparing the actual building against a notional building of the same size and shape. Compliance is demonstrated through two primary metrics calculated using the Simplified Building Energy Model (SBEM) or similar approved tools.
- Target Primary Energy Rate: Measured in kWhPE/m² per year.
- Target Emission Rate: Measured in kgCO₂/m² per year.
- BRUKL Report: A standardized compliance report must be submitted at both the design stage and the as-built stage.
- Nearly Zero-Energy Buildings: Requirement 25B mandates that all new buildings must meet the nearly zero-energy standard.
Limiting Heat Gains and Losses
The document sets limiting standards for the building fabric to prevent unwanted heat loss in winter and excessive solar gain in summer. These standards apply to new elements, replacements, and renovations of existing thermal elements.
- Limiting U-values: New walls must not exceed 0.26 W/(m²·K), flat roofs 0.18 W/(m²·K), and windows 1.6 W/(m²·K) or Window Energy Rating Band B.
- Airtightness: New buildings generally require pressure testing, with a maximum air permeability of 8.0 m³/(h·m²) at 50Pa.
- Thermal Bridging: Linear thermal transmittance must be calculated following BRE's BR 497 or using generic values increased by 0.04 W/(m·K) or 50%.
- Solar Gain: Occupied or mechanically cooled spaces must limit solar gains through glazing from April to September inclusive, based on reference systems in Table 4.3.
Building Services Efficiencies and Controls
Fixed building services must meet minimum seasonal efficiency standards and be equipped with effective controls to ensure they use no more fuel than is reasonable.
- Boiler Systems: In new buildings, single natural gas boilers (≤2MW) require a seasonal efficiency of at least 93%.
- Heat Pumps: Air-to-air heat pumps (≤12kW) require a Seasonal Coefficient of Performance (SCOP) of at least 2.5 for space heating.
- Lighting: General lighting must achieve an average luminaire efficacy of 95 luminaire lumens per circuit-watt or use the Lighting Energy Numeric Indicator (LENI) method.
- Building Automation and Control Systems: Mandatory for new or existing buildings with heating or air-conditioning systems over 180kW effective rated output.
Work on Existing Buildings and Consequential Improvements
Specific regulations apply when extending or renovating existing non-domestic buildings. If a building has a total useful floor area over 1000m², certain works trigger the requirement for Consequential Improvements.
- Major Renovations: Defined as the renovation of more than 25% of the external building envelope surface area, requiring the whole element to be improved to current standards.
- Extensions: Large extensions (over 100m² and 25% of the existing floor area) are treated as new buildings for calculation purposes.
- Regulation 28: Triggers additional energy efficiency work when an extension is built or when the capacity of fixed building services is increased in buildings over 1000m².
- Material Change of Use: Conversion to uses such as hotels, shops, or public buildings requires existing thermal elements to meet threshold U-values.
Frequently Asked Questions
What is the maximum U-value for a window in a new non-domestic building?
The maximum area-weighted U-value for windows in new buildings is 1.6 W/(m²·K), or they must meet Window Energy Rating Band B for buildings similar to dwellings.
What are the 2023 amendments for district heat networks?
The 2023 amendments removed the primary energy factor as a performance standard for buildings other than dwellings when connected to district heat networks.
When is a building automation and control system (BACS) mandatory?
A BACS must be installed in new or existing buildings if the space heating or air-conditioning system has an effective rated output greater than 180kW.
What is the simple payback period for consequential improvements?
Measures are generally considered economically feasible if they achieve a simple payback of 15 years or less, though a shorter 7-year period applies to some energy-generating systems.
How soon after completion must a pressure test notice be given to the local authority?
The notice of pressure test results must be given to the local authority not later than seven days after the final test is carried out.
Are listed buildings exempt from Approved Document L Volume 2?
Work to listed buildings or those in conservation areas does not need to comply fully if compliance would unacceptably alter the building's character or appearance.
What is the minimum seasonal efficiency for a new gas-fired boiler over 2MW?
For single-boiler systems with an output greater than 2MW in new buildings, the minimum seasonal efficiency is 88%.
What constitutes a 'major renovation' under Regulation 35?
A major renovation is defined as the renovation of a building where more than 25% of the surface area of the building envelope undergoes renovation.
