London Plan Urban Greening Factor (Policy G5) — A Scored Greening Requirement for Major Developments, Reviewed Across 494 Applications

Policy G5 of the March 2021 London Plan requires major developments to include urban greening, measured by an Urban Greening Factor (UGF): a score from 0 to 1 weighting surface types (e.g. trees in connected pits, green roofs, rain gardens, species-rich grassland, permeable paving) by area. Interim targets are 0.4 for predominantly residential and 0.3 for predominantly commercial schemes; boroughs may set local targets.
The GLA commissioned Arup to review the policy. The review analysed 494 major applications across the 32 boroughs from Planning London Datahub (to April 2025), ten case-study sites, a workshop, and questionnaires to developers and planning authorities. Mean stated scores sat around the targets for most typologies (for example 0.43 for 4–12 storey residential blocks and 0.42 for residential towers of 13+ storeys), while industrial schemes, not covered by the policy, averaged roughly 0.2–0.23. Student and co-living towers in inner London averaged 0.30.
Findings: broad support for the policy; UGF does not block other objectives such as BNG or PV; difficulties include roof-space conflicts, structural loading, fire and maintenance concerns, and long-term management. In the ten case studies the stated UGF score was delivered, with no post-approval amendments, but the review notes that built-out scores are not systematically monitored. Recommendations: remove the requirement for borough-specific scores, add an industrial score of 0.2, clarify UGF/BNG synergies and require evidence that UGF has been addressed. The evidence is on planning-stage scores, not measured ecological or hydrological outcomes.

Read the full analysis: https://www.london.gov.uk/publications/urban-greening-factor