Councils set to require more than 10% biodiversity net gain should have policy defence lined up, advises Natural England

Planning authorities intending to require developers to deliver more than 10% biodiversity net gain on new projects come November must ensure they have got “robust local evidence” to defend their policies, Natural England has advised.

In November this year it will become mandatory for developers to deliver a minimum 10% biodiversity net gain (BNG) on most new developments.

The policy is a cornerstone of how the government intends to meet some of its more ambitious nature recovery goals - including the target to halt the decline of species by 2030. Some local councils have engaged enthusiastically with it, such as Cambridge County Council which is already requiring developers to deliver 20% BNG.

However, in the last few months ENDS has heard from environmental lawyers concerned about grey areas where the Environment Act and planning policy meet, which they warn could see conflicts fast approaching.

MORE: What are the biodiversity net gain ‘elephant traps’ lying in wait?

For example, while the Act requires a “minimum” of 10% BNG, any council requiring more can only do so via policy. For the BNG condition to be discharged, developers are not legally obliged to deliver more than that, making any surplus that a council requires subject to challenge. 

At a Westminster Energy, Environment & Transport Forum on 15 June, ENDS asked Natural England’s principal advisor on BNG, Dr Nick White, about this conflict between the act and policy. 

He said that councils are able to require developers to deliver more than 10% BNG, but any considering doing so should consider two things: “If you're looking to go beyond 10%, I think our advice would be make sure you've got robust local evidence and set out your requirements very clearly in your local plan. Because although a [developer] won't be able to challenge 10% on viability grounds, they could challenge beyond 10%. And so make sure you've got your arguments lined up to defend your policy and be clear on what your policy is.”

He added that the 10% BNG refers to the baseline biodiversity value of the site in question, “so although on some sites people find it genuinely quite easy to achieve a 10% gain, on others, it will genuinely be quite challenging for them to do that because of the existing nature of the site. So do think about how this will get implemented in practice in your local area.”

Related: How some of the UK’s top developers have sought to weaken biodiversity net gain reforms

Penny Simpson, lead partner for environment at law firm Freeths, confirmed to ENDS that any requirement more than 10% was open to become “subject of debate over planning balance”. 

Simpson has previously called on DEFRA to help unmuddy the waters by producing a statutory instrument “that explains what the planning authority must take into account when it's approving that gain plan”. 

Speaking at a BNG conference convened in London in early March, she said: “If we don't get the clarity of how to mesh [the two] together through that statutory instrument, we are going to have a situation where people are saying, ‘but I've done what the Act requires and you're still telling me I need to do more under policy’. That is clearly not right. And the answer is, again, DEFRA to sort it out through the statutory instrument.”