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Biodiversity Net Gain for new development - implications

Last month my planning colleague, John Bosworth, published an article outlining which biodiversity net gain (BNG) policies have so far come into force. This summarised how the requirement to provide a minimum of a 10% biodiversity gain must be realised by way of on-site measures, off-site measures or purchasing statutory biodiversity credits from the Government, as well as the categories of exempt development. 

Here we look at what the developer must do to satisfy the policies that have come into force thus far. 

Planning Conditions - Producing the BNG assessment

Many councils have been applying BNG to planning decision-making prior to it becoming mandatory. However, they are now bound to do so. The main way in which BNG provisions will be satisfied is by the inclusion of a condition in the planning permission. This will stipulate that the development may not begin unless a BNG plan has been submitted to the Local Planning Authority (LPA) and the LPA has then approved the plan.

Practically, this will entail the developer instructing their planning consultant to produce the BNG assessment, alongside the usual suite of documents that are submitted as part of a planning application. This should contain the policy background, followed by a condition assessment of the current site. 

The condition assessment should provide calculations for each distinct habitat within a development site, based upon the size of the area, its distinctiveness, and its condition. This provides a numerical value for the current habitat. This can then be compared against the potential future habitat that is to be retained, lost, or enhanced.

The next part of the assessment should set out the various ways in which the scheme will (hopefully) enhance on-site biodiversity, ranging from window boxes and the border shrubs at the lower end of the scale, to green walls/roofs at the other. 

Finally, the BNG assessment should confirm the % net gain for the habitats as a whole, as well as the total biodiversity units delivered by the proposal. If the existing site is an urban or brownfield site, then it’s not uncommon for the % uplift to be in the millions, which can appear somewhat jarring. 

However, with undeveloped, greenfield sites, it’s likely that development will result in a net loss to biodiversity. The applicant will have to demonstrate how the uplift is going to be met by way of on-site measures, and where that’s not possible, through off-site measures. As a last resort the uplift can be achieved through purchasing statutory biodiversity credits from the Government. 

We’ll have to wait and see whether the automatically imposed condition which requires a post permission submission is overtaken by BNG assessments that are submitted up front when the application itself is submitted.

Section 106 Agreements

While planning conditions can help secure a range of measures to make a planning application acceptable to the LPA, these usually relate to the material, method of construction or hours of use. They are less appropriate for securing long term objectives, such as the future maintenance of biodiversity sites. Planning conditions must also be directly relevant to the property in question, which as we have seen above, may not always be the case when it comes to BNG obligations. 

As a result, apart from small scale on-site contributions, ongoing obligations to provide BNG may have to be included in Section 106 Agreements and Unilateral Obligations. This may include covenants given by the owner:

  • to meet and maintain the agreed BNG threshold through measures set out in a management plan, and provide calculations to the LPA;
  • not to occupy or permit occupation until the agreed BNG threshold is not achieved;     
  • where it fails to meet the agreed BNG threshold, to implement other specific measures to ensure that it is met; and
  • where this is not possible, to agree to implement off-site measures or pay a contribution to the LPA, again usually prior to occupation 
Conservation Covenants 

To assist with the implementation of BNG regulations, the Government has simultaneously introduced the concept of Conservation Covenants between a conservation body and the landowner. It is recognised that where a developer seeks to meet its BNG obligations through off-site contributions, tracts of land will have to be set aside for re-wilding. As BNG requirements require the 10% uplift be retained for 30 years, this land must be conserved and maintained throughout that period, to ensure that the gain is realised. 

The use of conservation covenants is likely to move us to a more regimented system for legally binding private agreements between a conservation body and the landowner. These obligations will then bind all subsequent landowners either until the specified term of the conservation covenant expires or in perpetuity. 


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