Biodiversity Net Gain in the balance?

Weston Homes Plc, R (On the Application Of) v Secretary of State for Levelling Up, Housing and Communities & Anor [2024] EWHC 2089 (Admin) (07 August 2024)

This is an interesting case that considered the weight to be given to biodiversity net gain (BNG) when deciding whether to grant planning permission.

Weston Homes challenged a Planning Inspector’s decision to refuse planning permission for 96 dwellings on six grounds, four of which were successful including one on BNG, which is the one we consider in this briefing.

Background

At the time of the planning application, the local planning authority's policy encouraged the provision of BNG, but it did not set a numerical target as a requirement for the grant of planning permission. The development was not subject to the mandatory BNG condition (*) because the application was submitted before mandatory BNG was introduced.

However, it was accepted that the development would achieve BNG of more than 10%. The ecological assessment found that the proposed development would result in an on-site increase of 15.53% in area habitat units, an increase of 68.04% in hedgerow units, and an increase of 2.48% in watercourse units.

The Inspector assigned only a moderate benefit to achieving BNG above 10% - the Court considered the following paragraph of the Inspector's Decision Letter (DL) was critical:

"80. Most of the list of claimed environmental credentials of the proposed development amounts to no more than policy-compliant measures and are neutral factors in the planning balance. The net biodiversity gain in excess of 10% I put at moderate only, given there was uncertainty over the estimated net gain for the watercourse units."

The decision

The Court considered that the Inspector had given insufficient weight to BNG when refusing to grant planning permission.

The Inspector had erred in law when he reduced the weight to be given to the BNG estimated for the proposal by considering a future legal requirement for BNG. Further, the reasons given by the Inspector in relation to their assessment of the proposal's BNG were legally inadequate.

Mr Justice Holgate's judgment

Mr Justice Holgate found the Inspector should have explicitly dealt with any BNG below 10%. Mr Justice Holgate stated that the: 

"poor drafting of the DL in relation to BNG resulted in a disproportionate amount of time being spent during the hearing trying to understand the text. The absence of a logical chain of reasoning amounts to irrationality."

What does this decision mean now that the new mandatory BNG requirement will apply to most applications?

James Clark, Managing Associate in the Planning team at WBD said,

"The issue in this case was how a decision taker should approach the weight to be attached to BNG to be delivered by a development where the mandatory BNG condition does not apply. This decision may provide useful guidance on how BNG should be treated in the planning balance for applications made before the introduction of the new mandatory BNG requirement and in future cases e.g. where the mandatory BNG condition does not apply, e.g. exempt development.

For developments where the new mandatory BNG requirement does not apply but where local planning policy requires a net gain to be delivered, the decision maker should still expressly consider any BNG enhancement below the policy requirement as part of the planning balance. Adequate reasons will need to be given, particularly for any refusal of planning permission based on the BNG proposed.

For developments subject to the new mandatory BNG requirement, the current national planning practice guidance (PPG) states that it would generally be inappropriate for decision makers, when determining a planning application for a development which is not exempt, to refuse an application on the grounds that the BNG requirement will not be met.

As developers must apply the biodiversity gain hierarchy under which as a last resort, they may purchase statutory credits (where they are unable to provide BNG on site or off site), it must be right that it will be generally inappropriate to refuse planning permission on the ground that mandatory BNG has not been secured. It will be interesting to see if this is how authorities proceed and how this plays out in practice."

Note (*) mandatory BNG condition: a condition requiring mandatory BNG of at least 10% applies to planning permissions granted pursuant to a planning application made on or after 12 February 2024 (or 2 April 2024 for small developments). This is except for instances where an exemption applies. Such exemptions include permissions granted under a development order, where a "de minimis" amount of habitat is affected by a development and certain self-build or custom housebuilding projects.