In January this year, the Department for the Environment, Food and Rural Affairs (DEFRA) published A Green Future, its 25-year environmental plan. The document promised a consultation on "strengthening" requirements for planning authorities to ensure that "environmental net gains" are achieved from new development.
Last week, the government started consulting on a mandatory requirement for new development to deliver biodiversity net gains. According to the consultation document, net gain "is an approach to development that aims to leave the natural environment in a measurably better state than beforehand". DEFRA said that developers would be "required to demonstrate how they are improving biodiversity – such as through creating green corridors, planting more trees, or forming local nature spaces". In the "rare circumstances" where mitigation is not possible, the consultation "proposes to charge developers a levy to pay for habitat creation or improvement elsewhere". Net gain will be measured using the "DEFRA metric" system, which assesses and quantifies levels of biodiversity.
Environmental groups have historically been sceptical about such offsetting policies, suggesting developers may exploit the approach by simply paying for the right to destroy important ecological sites. Friends of the Earth, for example, has described DEFRA’s net gain proposals as a "licence to destroy nature". But Simon Marsh, head of sustainable development at the RSPB, offered a more optimistic assessment of the latest consultation. "If we get this right, it has the potential to be a game changer for the way that biodiversity is dealt with in the planning system," he said. Marsh said the fact that net gain policies will be mandatory is key. "You need to get consistency across the whole of the country to make it work properly," he said. The consultation focus on the planning system’s "mitigation hierarchy", which prioritises conservation of habitats and mitigation over compensation, should help to address concerns about the destruction of existing biodiversity sites, he added.
Laura Homfray, assistant biodiversity consultant at WSP, co-authored a 2016 report that called for biodiversity net gain to be incorporated into national planning policy. "Although some people are criticising biodiversity net gain approaches, current planning policy is leading to developments that result in a net loss of biodiversity," she said. "So that approach is clearly not working." The report’s co-author, technical director for biodiversity at WSP Tom Butterworth, acknowledged that some developers may see the net gain requirement as an unwelcome burden. However, he said the proposal introduces certainty, compared with the National Planning Policy Framework, which merely says net gains should be achieved where possible. "That’s quite difficult to interpret," said Butterworth. "Clarity is really important here."
Warwickshire County Council was one of several local authorities chosen by DEFRA to pilot net gain policies back in 2012. David Lowe, ecology team leader at Warwickshire, said: "That took a lot of resources to get up and running. We’ve now done that hard work so it will be easier for others to pick up and use." Lowe said councils should expect to invest in biodiversity expertise when implementing net gain policies, particularly if ecological issues have been neglected in the past. But the policy should swiftly become self-financing, he said, with sums paid by developers to offset their impact on biodiversity used in part to pay for the operation of net gain programmes. "Once this gets going, it can potentially be 100 per cent cost recoverable," he said.
How a proposed 'net gain' policy would work
- When assessing potential development sites, developers carry out surveys to identify habitats and their conditions.
- Councils and applicants follow a "mitigation hierarchy" which prioritises options that avoid harm to biodiversity, followed by mitigation measures, then compensation as a last resort.
- To compensate for biodiversity loss, new habitats are created or enhanced, preferably as part of the same development or nearby.
- Where there are no suitable local compensation opportunities, a tariff is used to fund habitats for biodiversity priorities elsewhere.