Biodiversity Net Gain

BNG is calculated using a biodiversity metric, which measures the biodiversity value of habitats in ‘biodiversity units’ as a proxy for nature.

The metric can be used to calculate how a development might change the biodiversity value of a site with respect to habitat size, condition, distinctiveness and location. By comparing biodiversity value of habitats found on a site before and after development, the net gain in biodiversity is determined.

To calculate the number of biodiversity units for existing habitat, or habitat enhancements to achieve BNG, the statutory biodiversity metric tool must be used.

The statutory biodiversity metric tool and guidance on its use are available at: Statutory biodiversity metric tools and guides - GOV.UK

Hertsmere supports a variety of wildlife rich priority habitats. There are a number of habitats in the borough protected as internationally important, including oak-hornbeam woodlands. In Hertsmere there are Sites of Specific Scientific Interest, local nature reserves, regionally important geological sites, local wildlife sites and woodlands. Priority habitats in the borough include woodland, grassland, heathland, wetland, along with rivers and ponds which support a wide range of flora and fauna.

Hertfordshire Local Nature Recovery Strategy (LNRS) sets out the vision for a resilient network for nature across Hertfordshire, by connecting, enhancing and creating places for wildlife, so that nature can thrive. The LNRS is intended to be used by farmers, land managers, developers, communities, public organisations and policy makers to enable them to deliver the most effective actions for nature.

Local Nature Recovery Strategy | Hertfordshire County Council

• At the design stage: Applicants are encouraged to consider biodiversity net gain early in the development process and factor it into site selection and design. Developers should take the Hertfordshire Nature Recovery Strategy into consideration at the design stage.
• When making a planning application: Minimum national information requirements related to biodiversity net gain must be provided with the planning application. These requirements will establish the pre-development biodiversity value of the development’s onsite habitat.
• Planning decision-making: When determining a planning application, biodiversity net gain will often be a material consideration. Planning Officers may ask for further information, if needed.
• Securing BNG as planning obligation: Through the imposition of conditions and agreement of section 106 planning obligations significant onsite biodiversity gains and registered offsite biodiversity gains will be secured.
• Before commencement of the development: The biodiversity gain condition is a pre-commencement condition: once planning permission has been granted, a Biodiversity Gain Plan must be submitted and approved by the planning authority before commencement of the development.
• Monitoring and enforcement: Finally, following the approval of the Biodiversity Gain Plan and commencement of development, Hertsmere will monitor the implementation of biodiversity net gain Plan and, where appropriate, take enforcement action if commitments relating to the Plan are not met.

Biodiversity Gain Plans are expected to follow the biodiversity hierarchy:

• Through site selection and layout, developers should avoid or reduce any negative impact on biodiversity.
• If harm cannot be avoided, compensation and at least 10% Biodiversity Net Gain, as measured by the statutory biodiversity metric, must be delivered.

There are 3 ways a developer can achieve BNG.

• They can create biodiversity on-site (within the red line boundary of a development site).
• If developers cannot achieve all of their BNG on-site, they can deliver through a mixture of on-site and off-site. Developers can either make off-site biodiversity gains on their own land outside the development site, or buy off-site biodiversity units on the market.
• If developers cannot achieve on-site or off-site BNG, they must buy statutory biodiversity credits from the government. This should be a last resort. The government will use the revenue to invest in habitat creation in England.

Developers can combine all 3 options, but must follow the steps in order. This order of steps is called the biodiversity gain hierarchy.

Further information on the biodiversity net gain hierarchy is available at: Understanding biodiversity net gain - GOV.UK

Details on what should be included in the Biodiversity Net Gain Plan is available at: Biodiversity net gain - GOV.UK

Off-site gains refer to any biodiversity gains to be delivered on land outside of the red-line boundary of a development. Developers can either buy off-site units from a land manager, or make off-site gains on your own land outside the development site. Any land proposed for use for off-site BNG must be a registered biodiversity gain site or a habitat bank.

If the developer wishes to make off-site gains on their own land, they are the land manager as well as the developer. In which case, they will be expected to fulfil the responsibilities of both the developer and the landowner.

Further information on the responsibilities are available here:

Make off-site biodiversity gains as a developer - GOV.UK

Sell biodiversity units as a land manager - GOV.UK

For the administration of this planning requirement, different fee will be charged based on the size and technical difficulty of the application. This fee will cover the cost of technical assessments, local land charges, officer time and other administrative costs.

For general guidance:

• Small sites (1 to 5 ha) - £5,000 to £7,000
• Medium sites (5.01 to 20 ha) - £6,000 to £10,000
• Large sites (20.01 ha and above) - £7,000 to £15,000

These charges represent fees from Hertfordshire County Council and Hertsmere Borough Council. Hertfordshire County Council may revise their fees at their discretion. Likewise, Hertsmere Borough Council retains the right to revise its fees as deemed necessary.

Where an applicant believes the development would be subject to the biodiversity gain condition, the application must be accompanied by minimum information set out in Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015:

• confirmation that the applicant believes that planning permission, if granted, the development would be subject to the biodiversity gain condition;
• the pre-development biodiversity value(s), either on the date of application or earlier proposed date (as appropriate);
• where the applicant proposes to use an earlier date, this proposed earlier date and the reasons for proposing that date;
• the completed metric calculation tool showing the calculations of the pre-development biodiversity value of the onsite habitat on the date of application (or proposed earlier date) including the publication date of the biodiversity metric used to calculate that value;
• a statement whether activities have been carried out prior to the date of application (or earlier proposed date), that result in loss of onsite biodiversity value (‘degradation’), and where they have:
  • a statement to the effect that these activities have been carried out;
  • the date immediately before these activities were carried out;
  • the pre-development biodiversity value of the onsite habitat on this date;
  • the completed metric calculation tool showing the calculations, and
  • any available supporting evidence of this;
• a description of any irreplaceable habitat (as set out in column 1 of the Schedule to the Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024) on the land to which the application relates, that exists on the date of application, (or an earlier date); and
• plan(s), drawn to an identified scale and showing the direction of North, showing onsite habitat existing on the date of application (or earlier proposed date), including any irreplaceable habitat (if applicable).

Further details on information that should be submitted are available at: Biodiversity net gain - GOV.UK

Certain developments may be exempt from BNG rules:

• Planning application made before 12 February 2024
• Variations of planning permission
• Developments below the threshold
• Householder applications
• Self-build and custom build applications
• Biodiversity gain site
• High speed rail transport network
• Other exemptions including Urgent crown developments and developments that are granted planning permission by a development order (including permitted development rights)

Further details on these are available at: Biodiversity net gain: exempt developments - GOV.UK

Detailed Guidance on Biodiversity Net Gain with answers to Frequently Asked Questions are available at: Biodiversity net gain - GOV.UK

Guidance on what steps landowners need to take are available at: Meet your BNG requirements: steps to take for land managers - GOV.UK

Guidance on what steps developers need to take are available at: Meet biodiversity net gain requirements: steps for developers - GOV.UK

Guidance on what local planning authorities should do are available at: Biodiversity net gain: what local planning authorities should do - GOV.UK