Biodiversity net gain rules extended to small developments

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(Image: Biodiversity © Leklek73 via

Biodiversity net gain (BNG) rules in England have been extended to small developments, following their delayed introduction for major developments in February.

Introduced in the Environment Act 2021, BNG rules require new housing, commercial and infrastructure developments to be ‘nature positive’.

This means developers in England must now deliver 10% BNG, which can be achieved by creating new habitats and green spaces on residential projects with 10 or more dwellings, or where the site area is 0.5 ha or more.

From 2 April, BNG is also mandatory for small developments. Small sites are typically those with fewer than 10 homes on a site of less than 1ha or commercial development where floor space created is less than 1,000 square metres or total site area is less than 1ha.

There are some exemptions to BNG, so not all small developments will have this requirement. For example, self-build applications of no more than 9 dwellings or on a site smaller than 0.5ha are exempted from BNG.

‘It will take the industry time to adapt’

Delays with BNG introduction, which was due to come into effect in November 2023, caused uncertainty in the built environment sector. Concerns remain about the readiness of both industry and planners to manage this, as both continue to scale up resources and knowledge.

Amanda Williams, head of sustainability at CIOB, said: “The increased focus on BNG is very welcome however there is still some concern about the readiness of both the industry and planners to manage this new requirement, as both continue to scale up resource, knowledge and skills. Although an additional two months was allowed for developers of smaller sites to prepare, they will most likely have fewer resources to address this.

“It will take time for our industry to adapt to the complex new legislation and understanding will need to be shown by regulators, particularly while there continues to be a shortage of experts such as ecologists to factor BNG into project plans, deliver it and monitor success.”

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