Renewable Electricity Generation Requirements
A new functional requirement in the Building Regulations mandates renewable electricity generation on new dwellings. For non-domestic buildings, solar PV is included in the notional building. Here is the complete picture.
New Part 6 Functional Requirement (Dwellings)
For new dwellings (and buildings containing dwellings), the government has created a new functional requirement for renewable electricity generation. The system must be installed on the building or within the boundaries of its curtilage, and must be designed to enable generated electricity to be available for use by residents. This is a legal requirement, not just a notional building assumption — making it enforceable independently of the whole-building energy calculation.
40% Ground Floor Area Guidance
The Approved Document states that the Secretary of State considers the requirement met if solar panels equivalent to 40% of each dwelling's ground floor area are installed. However, other renewable methods can be used. The guidance also sets out where lower PV coverage is reasonable — for example, where architectural features like dormer windows, complex roofscapes, or shading prevent full coverage. Guidance includes how to calculate available roof space for various common design features.
Minimum Threshold
If the available roof space cannot produce at least 720kWh per year — roughly equivalent to fewer than 2 PV panels — no solar panels need be installed. This protects against situations where installing a very small system would be impractical or deliver negligible benefit.
Exemptions
Buildings with a storey at least 18 metres above ground level that contain dwellings are exempt. This mirrors the Higher-Risk Building threshold. The exemption also applies where equivalent renewable electricity generation is available from a directly connected off-site system (microgrid provision), enabling innovative shared-generation approaches.
Non-Domestic Buildings
Non-domestic buildings use the notional building approach rather than a functional requirement. Solar PV at 40% of the building's foundation area is included for both top-lit and side-lit spaces. Exceptions include unheated buildings with low electricity consumption and certain Higher-Risk Buildings. The notional building approach retains flexibility — developers can trade off solar coverage against other energy efficiency improvements.