The Urban Greening Factor (UGF) is the scoring tool London uses to make sure new development includes enough green infrastructure. Set out in London Plan Policy G5, it gives every scheme a single number between 0 and 1 based on how much of the site is greened and how valuable that greening is. If you are preparing a sustainability statement for a London site, the UGF is one of the first calculations a planning officer will expect to see.
This guide explains what the Urban Greening Factor is, how the score is worked out, the target figures to aim for, and the practical moves that lift a weak score — useful across the country as more authorities adopt greening factors of their own.
What is the Urban Greening Factor?
Policy G5 of the London Plan asks major developments to “contribute to the greening of London by including urban greening as a fundamental element of site and building design”. The UGF turns that ambition into a number. The Mayor sets two interim target scores:
- 0.4 for developments that are predominantly residential;
- 0.3 for predominantly commercial development.
The point of the factor is to reward greening that is designed in from the start rather than added as an afterthought, and to value high-quality, biodiverse surfaces over token planting. It sits alongside — but is separate from — biodiversity net gain, which is a national requirement measured in a different way.
How the Urban Greening Factor score is calculated
The calculation is a weighted average. Each type of surface on the site is given an area (in square metres) and multiplied by a “surface cover factor” between 0 and 1 that reflects its ecological and water value. You add up all those weighted areas and divide by the total site area:
UGF = Σ (surface area × factor) ÷ total site area
The factors run from high-value living surfaces down to hard, sealed ground. Illustrative values from the Policy G5 table include:
- Semi-natural vegetation, maintained or established (woodland, species-rich grassland): 1.0
- Wetland or open water, semi-natural: 1.0
- Intensive green roof with substrate over 150mm and diverse planting: 0.8
- Standard trees planted in connected tree pits with at least 1m³ of soil: 0.8
- Extensive green roof with substrate of at least 80mm; flower-rich perennial planting: 0.7
- Green wall / facade-bound planting: 0.6
- Amenity grassland (regularly mown lawns): 0.4
- Permeable paving: 0.1
- Sealed surfaces (concrete, asphalt, waterproofing): 0.0
The full table is longer, but the logic is clear: a living roof or a properly planted tree pit does far more for the score than a mown lawn, and a sealed car park does nothing at all. A tight urban site dominated by hard surfacing will struggle to reach 0.4 unless roofs and walls are brought into play.
How to lift your Urban Greening Factor score
Because the factor is area-weighted, the biggest gains come from turning otherwise dead surfaces into living ones:
- Green roofs. A flat roof is usually a 0.0 sealed surface; an extensive green roof lifts that same area to 0.7 or an intensive one to 0.8. On a building with a large footprint this is often the single most effective move.
- Trees in proper pits. Standard trees in connected soil volumes score highly and add canopy, shade and rainfall interception.
- Living walls and facade planting. Where ground space is scarce, vertical greening at 0.6 adds score and visual quality.
- Rain gardens and vegetated SuDS. Planted drainage features score well and do double duty on surface water — a genuine sustainability win.
The wider benefits are real, not just points on a form: green infrastructure cools urban areas by an estimated 2–8°C during heatwaves, manages rainfall and supports wildlife. That is why the momentum behind urban greening has grown through 2026, with cities across England putting nature at the heart of new development.
The Urban Greening Factor beyond London
Although the UGF originates in the London Plan, the approach is spreading. A growing number of local authorities are introducing greening factors or green-space standards in their local plans, and national planning policy increasingly expects new development to deliver measurable environmental improvement. Even where no formal UGF applies, demonstrating a strong greening strategy in your sustainability statement helps show a scheme meets policy on climate resilience and biodiversity.
How Fortress Associates can help
Fortress Associates produces automated sustainability statements for planning applications across every UK local authority. Each statement covers energy, water efficiency, biodiversity net gain, urban greening and BREEAM where required — and for London sites it addresses the Urban Greening Factor under London Plan Policy G5. The report is free and ready in minutes. Start on our sustainability statement page, explore our full range of services, or get in touch through contact.
Sources & further reading
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