Biodiversity Net Gain Planning: How to get your development approved 

Over the years, biodiversity has declined significantly in the UK, and many environmental groups have called for a change in order to stop the negative effect on the environment. As such, the biodiversity net gain initiative was launched to leave the natural environment in a measurably better state and prevent further damage to it.

Biodiversity net gain (BNG) is an approach to development that aims to leave the natural environment in a better state than it was before the development project took place. Previously, planning policy has encouraged developers to achieve “no net loss” for biodiversity. However, there has not been an official requirement until now.

Biodiversity Net Gain is being requested more frequently by Local planning authorities to inform planning applications. The aim is to show how the proposed development will be of benefit to biodiversity in a measurable way. The national planning policy framework also requires BNG.

Biodiversity net gain requirements for planning

Following the passing of the Environment Bill, the Environment Act will be introduced in Autumn 2023. This Act contains key changes to environmental law and will make biodiversity net gain become a legal requirement for all future development projects in the UK. The Act will require all developments to meet the following requirements:

• Developers must deliver BNG to a minimum of 10% net gain through their schemes; this will be measured through a metric, currently Metric 4.0.
• A developer will be required to demonstrate how they will deliver biodiversity net gain by creating or enhancing habitats. Implementing BNG can be demonstrated through the production of detailed Landscape Planting Schemes, Landscape Management Plans and Monitoring assessments for on and/or off-site.
• A mitigation hierarchy is to be followed and demonstrated to avoid, minimise or compensate. If it is not possible to compensate on the development site, then offsetting will be required elsewhere. This will be done through discussions of third party land owners, the council, landbanks or wildlife charities.
• Developers will have to guarantee the biodiversity gain is maintained for at least 30 years (as outlined in Landscape Management Plans).
• New local nature recovery strategies (LNRS) will be prepared to geographically cover England by “responsible authorities”. This will encourage habitat creation and enhancement in the right places.
• Conservation covenants will be a mechanism used to deliver this (this approach is in preparation by Defra and Natural England).
• A national register of land used for biodiversity gain will be established. This will involve setting up a new biodiversity credits market.
• Metrics are only concerned with habitats and do not take protected species into consideration.
• Other ecological legislation and policies still apply.

Calculating biodiversity net gain for planning

During the planning process, a calculation of a developments biodiversity score should be conducted. Biodiversity unit values will be assigned by metrics to every habitat on a site according to their relative importance for biodiversity.

Comparisons can then be made between the existing value of a site and what will be delivered through development or management and post development. This may include an increase in natural habitats through retention and enhancement and/or creation.

Biodiversity net gain can be calculated through the DEFRA biodiversity metric 4.0, which requires a limited number of factors. These factors include:

 The type of habitat (both on and off site)

• Any locations (if they are local environment priorities)
• The size of habitat parcels in kilometres or hectares
• The condition of any habitat parcels

The government website also provides a biodiversity metric 4.0 calculation tool, which can help to determine your biodiversity unit score that translates into the standards of your local planning authority.