Biodiversity net gain (BNG)

What is Biodiversity net gain?

Biodiversity Net Gain is defined as delivering more or better habitats for biodiversity and demonstrating this through use of the Statutory Defra Biodiversity Metric.

It encourages development that delivers biodiversity improvements through habitat creation or enhancement after avoiding or mitigating harm. Biodiversity Net Gain involves an approach whereby developers work with stakeholders to support their biodiversity goals.

Biodiversity net gain is important.

It allows development and land management to have a positive impact on nature.
It leaves the natural environment in a better state than it was before.
It does this by enhancing, creating, and increasing habitats on the site.
This helps to increase the wildlife in the area.

Do I need to understand Biodiversity net gain?

You will need to understand the requirements of BNG if you are a:

Developer
Land Manager
Local Planning Authority

What does BNG apply to?

BNG applies to all land development to low water mark, except permitted development, which includes:

Brownfield development.
Change of use applications.
Temporary permissions.
Small sites/minor development – see below.

Mandatory BNG only applies to applications submitted after the commencement date for that application type.

Applications submitted prior to that date will be required to comply with the Local Plan 2016-2036 Policies ENV 7 and ENV8 only.

Some key differences are:

Local policy requires ‘a gain’ in biodiversity value whereas mandatory BNG requires a 10% gain,
We can take a financial contribution to compensate for on-site losses under local policy, we cannot take a financial contribution to meet the legislative requirements,
The legislative requirements include minimum information requirements to be submitted at validation whereas local validation requirements can be more detailed.

BNG in Darlington

All developments are required to achieve a minimum 10% Biodiversity Net Gain, apart from a few exemptions outlined on GOV.UK[external link]. The Environment Act 2021 mandated this requirement for Major planning applications submitted on or after February 12 2024, and 2 April 2024 for certain other planning application types.

This guidance has been produced to explain to developers:

The level of net gain for biodiversity that is expected in Darlington.
What written information you need to submit with planning applications to assess the measurable Biodiversity Net Gain.
What measures will be required if you cannot achieve 10% Biodiversity Net Gain On-site.
The role of Darlington Borough Council as the monitoring and reporting body for Biodiversity Net Gain.

Be aware that BNG does not replace the need to carry out other assessments for protected species or habitats. Protected species and habitat surveys will still be required, and any mitigation, compensation, or enhancement will still be required before biodiversity net gain is considered.

The authority will also still need to undertake a Habitats Regulations Assessment if there there may be impacts on European protected sites, such as:

Special Areas of Conservation, or
Special Protection Areas.

We recommend that applicants access our pre-application advice to enable early discussion on the BNG and ecology requirements for an application.

Darlington Borough Council requirements

We are seeking a minimum 10% Biodiversity Net Gain through the use of the Statutory Defra Biodiversity Metric. The net gain proposed must be meaningful and measurable.

From the earliest stage, proposals for new development should involve competent and experienced ecologists inputting into the various design and layout options to enable the minimum 10% Biodiversity Net Gain to be delivered On-site. Where this is not feasible (to be agreed with the Local Planning Authority) it may involve Off-site compensation.

The Local Planning Authority (LPA) will expect all applications to conform to this guidance to achieve consistency of information on which to carry out decision-making in a timely manner. Not following this guidance may lead to delays to the processing of your planning application, as the LPA requests further evidence that both a measurable and meaningful net gain is being achieved.

In seeking to ensure that the requirements for Biodiversity Net Gain are achieved, it is important that these issues are addressed at a very early stage in the application process. Consequently, applicants are encouraged to engage in the pre-application service.

There are numerous different ways that Biodiversity Net Gain can be achieved, one of these is to simply apply the Metric to an already designed layout and see what the numbers tell you. It is possible this approach will give you enough “numbers” to demonstrate you can achieve the minimum 10% net gain in biodiversity. However, Biodiversity Net Gain is more than just achieving biodiversity-by-numbers.

The "Good Practice Principles for Development" provide an industry-standard having been produced from a range of the UK’s most respected professional bodies. They provide a way for industry to prove that development projects have followed best practice.

These 10 Principles set out good practice for achieving Biodiversity Net Gain and must be applied together as one approach. It will be important to demonstrate against every Good Practice Principle that is has been considered and is being achieved. If only 9 out of 10 Principles are being achieved then Biodiversity Net Gain is not being achieved.

The objective should always be to deliver 10% Biodiversity Net Gain On-site and therefore it will be essential to appoint a competent and experienced ecological consultant at the earliest stage to be involved in the iterative design stage of the layout. The ecological consultant should work closely with the landscape architects and urban designers to consider which options of the layout lead to the best possible outcome for achieving Biodiversity Net Gain On-site.

This type of information should be included as part of and as a clearly distinguishable annex to the Design and Access Statement (if one is produced) or as a stand-alone assessment whereby different options of layout are shown with their corresponding different Biodiversity Unit outcomes. Where the layout resulting in the lowest impact on biodiversity has not been taken forward to the proposed layout stage an explanation should be provided why this option has been chosen over another.

Evidence should be submitted as part of the Ecological Impact Assessment to demonstrate the ecological consultant has been involved in the initial design stage of the layout in a meaningful way. This should include reference to the mitigation hierarchy of: avoiding damage to sensitive ecological features; minimising impacts on such sensitive ecological features; and where these first two steps cannot be achieved (with an explanation to justify why not) finally consider what level of compensation will be required either On-site or Off-site (or both).

Habitat creation credits

It is not always possible to create a habitat on a development site.

If this is the case, we can sometimes create habitats elsewhere in the local area.
If this is not possible, the Government has a system which allows developers to buy credits.
The credits are used to create habitats at a different location.

Developers can only buy credits once all other options for habitat creation, onsite and offsite, are exhausted.

Options for delivery of Biodiversity Net Gain

On-site

All land within the boundary of a project. In a planning context, this usually means within a red line boundary.

Off-site

Land outside of the red-line boundary, regardless of ownership, is classed as Off-site, even sites within the same ownership (usually labelled 'blue-line boundaries). Any blue-line areas need to be inputted in the Metric as Off-site, and implementation covered by a s106 and entered onto the Natural England National Sites Register.

Any site delivering ‘off-site’ biodiversity units must be registered on the Natural England ‘biodiversity gain site register’.

A legal commitment is required to create habitat enhancements and maintain them for at least 30 years after completion of the enhancements.

Statutory credits

The government has introduced Statutory Biodiversity Credits.

They can be purchased by developers to allow developments which are unable to meet their Biodiversity Net Gain on-site or off-site.

Credit sales revenue will be received by Natural England and invested in habitat creation projects.

Statutory Biodiversity Credits are a last resort. They will be much more expensive than securing Biodiversity Units more locally.

Clearing sites in advance

As of 30th January 2020, Schedule 14 of the Environment Act lets us take any habitat degradation or destruction into account.

We take the earlier habitat state as the baseline for the purposes of Biodiversity Net Gain.

This is to make sure there is no advantage gained by the deliberate clearance of land to achieve a low baseline value for Biodiversity Net Gain.

If habitats on site are destroyed or degraded before a survey and submission of planning application, the earlier habitat state will be taken as the baseline for the purposes of the biodiversity Metric.

In 2023, the Levelling Up and Regeneration Act 2023 (LURA), introduced additional wording further tightening of the law regarding degradation by extending the circumstances in which degradation can be addressed. This wording covered authorised and unauthorised activity on onsite and offsite habitats on or after the 25^th August 2023.

A habitat condition score of ‘good’ is allocated to any degraded habitat parcel as a precaution.

Please see the following link for advice to developers and ecologists for achieving BNG in Darlington.