Biodiversity net gain: Barrier or opportunity?

The principle of biodiversity net gain (BNG) is now heading full pelt towards the planning process – with big implications for landowners and developers.

In principle, BNG requires developers to ensure that habitats are enhanced, delivering at least a 10 per cent improvement in biodiversity. It is not yet a mandatory requirement, but February’s NPPF update sets a requirement to “identify and pursue opportunities for securing measurable net gains for biodiversity”.

When the environment bill gains royal assent at the end of the year local planning authorities (LPAs) will have a legal framework for targeting biodiversity enhancements.

Several LPAs are already imposing the NPPF requirements as policy. Planning applications, even those benefiting from an allocation, will need to ensure that they are submitted with BNG in mind. This is not something that will be resolved quickly post-validation alongside more generalised ecology comments. Developers must make sure their submission has appraised the impact of their proposals on biodiversity and that they are proposing a suitable response, ideally at pre-application stage.

“Several LPAs are already imposing the NPPF requirements as policy”

For example, a parcel of land proposed for residential development with a pre-development baseline biodiversity unit value of 100 would need to guarantee a 10 per cent gain in unit value (amounting to 110 units) either on site, off-site or a combination of both. If a council has a site already identified for BNG, then payment of a commuted sum through a s106 agreement might be possible.

The industry may see the introduction of BNG as another barrier to delivery imposed by the planning system. At best, where a solution is in place an application could be delayed while the consultant ecologist reaches a palatable level of compensatory land or contribution with the LPA’s ecologist.  

Cost is another impact. Schemes now burdened with CIL and s106 requests must factor BNG delivery into their appraisals. The costs of acquiring or leasing BNG land will vary. The current tariff proposed by Defra for off-site compensation is £9,000 to £15,000 per biodiversity unit (i.e. if you need to find 10 units to generate a 10 per cent net gain, you could be looking at a £90,000 to £150,000 contribution). Either approach would challenge viability on more marginal sites.

But for landowners BNG is an opportunity. Where land doesn’t benefit from immediate development potential it can be sold or leased for 30 years to a developer. 

Kate McClean is director of planning and development at Mellor Speakman

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