The Urban Greening Factor (UGF) is distinct from the Biodiversity Metric in that they provide two completely separate measurements and cannot be mixed. BIAC concentrates on ecological biodiversity while the UGF is more interested in the wider environmental benefits green infrastructure can provide.
It is a new policy initiative within the new London Plan 2021 (Policy G5: Urban Greening, pages. 322-325) and recognises the many positive advantages that green infrastructure can provide to urban locations, such as:
Urban Greening provides a score between 0-1 that measures the green cover across a particular area or site. It is distinct from the BIAC, and includes features such as green walls and roofs which can be counted in its score. It does not take into account the losses or gains in biodiversity or the value of individual habitats, its focus is on the overall ratio of built to natural landscaping. Each type of surface cover is given its own score (with certain features such as trees and semi-natural wetlands scoring a higher individual rating) and these are then used to determine the final score for a site. Unlike the BIAC quantity can make up for quality of green surface cover.
Typically, Urban Greening is something that is best addressed at an early stage of the design process through a landscape led planning approach, but it can be increased in later stages of the development through add-ons such as green walls/roofs or similar features.
The London Plan recommends a target score of 0.4 for predominantly residential developments, and a target score of 0.3 for commercial developments, although local boroughs can set their own target.
The Urban Greening Factor targets set by the local authority need to be met on site regardless of any planned offsite compensation proposed to increase a developments biodiversity Net Gain.
BIAC scores post-development usually needs to be equal to or greater (10%+) than the biodiversity Net Gain score prior to commencement while the Urban Greening Factor only needs to meet the target score, and thus can remain equal to or even decrease as a result of a development without issues so long as it remains above the target set out in the local plan.
Just like with the BIAC, the Urban Greening Factor is only meant to function as an assessment tool and should not be the sole method of determining urban greening.
What does the Urban Greening Factor mean for London? | Landscape Institute
Urban Greening Factor (adas.uk)
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