Biodiversity Net Gain
Legal Requirement
Under the Environment Act 2021, it is mandatory for developments (excluding exemptions) to deliver a minimum of 10% biodiversity net gain.
Biodiversity enhancement is also required under the National Planning Policy Framework (2024) and typically also under local planning policies.
Exemptions
The following types of development may be exempt from biodiversity net gain rules (though biodiversity enhancements may still be required under the National Planning Policy Framework):
- Existing planning applications.
- Variations of planning permission.
- Developments below the threshold (developments that do not impact a priority habitat and impacts less than 25m2 of onsite habitat and less than 5m of onsite linear habitats such as hedgerows).
- Householder applications.
- Self-build and custom build applications (developments that are a maximum of 9 dwellings on a site no more than 0.5 hectares).
- Biodiversity net gain sites.
- High speed rail transport network.
- Urgent crown developments.
- Developments that are granted planning permission by a development order (including permitted development rights).
Understanding Biodiversity Net Gain
Biodiversity net gain requires developments to ensure that habitats for wildlife are left in a measurably better state than they were before the development.
Measuring Biodiversity Net Gain
For the purposes of biodiversity net gain, biodiversity value is measured in standardised biodiversity units. Biodiversity units can be lost through development or generated through work to create and enhance habitats.
Biodiversity value is calculated using the statutory biodiversity metric by measuring how many biodiversity units are present on a site before development and how many biodiversity units are needed to replace the units of habitats lost and to achieve 10% biodiversity net gain. Areas of habitat, hedgerows and watercourses are subject to separate calculations.
Ways to Deliver Biodiversity Net Gain
Through site selection and layout, developers should avoid or reduce any negative impact on biodiversity. There are three ways a developer can achieve biodiversity net gain but these steps must be followed in order:
- They can create biodiversity on-site (within the red line boundary of a development site).
- If developers cannot achieve all of their biodiversity net gain requirements 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 (which will need to be included on the Biodiversity Net Gain Register), or buy off-site biodiversity units on the market.
- If developers cannot achieve on-site or off-site biodiversity net gain, 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.
The land owner is legally responsible for creating or enhancing habitat, and managing that habitat for at least 30 years to achieve the target condition. This applies if you make on-site gains or sell off-site gains on a site you own. If you buy off-site units, you are paying the land manager to manage the land for 30 years to achieve the target condition.
Good Practice Principles for Achieving Biodiversity Net Gain
These ten principles set out good practice for achieving biodiversity net gain and must be applied all together, as one approach.
- Apply the mitigation hierarchy. Avoid then minimise impacts on biodiversity. As a last resort compensate for losses onsite or, if not possible, offset offsite.
- Avoid losing biodiversity that cannot be offset by gains elsewhere. This means avoiding impacts to irreplaceable habitats which include ancient woodland, ancient and veteran trees, blanket bog, limestone pavements, coastal sand dunes, spartina saltmarsh swards, Mediterranean saltmarsh scrub and lowland fens.
- Be inclusive and equitable. Engage with stakeholders during design, implementation and monitoring of biodiversity net gain.
- Address risks. Mitigate for any uncertainty or risk to delivering biodiversity net gain and add contingencies.
- Make a measurable net gain contribution.
- Achieve the best outcomes for biodiversity. Use an evidence-based approach to biodiversity net gain design, implementation and monitoring.
- Be additional. Achieve nature conservation outcomes that exceed existing obligations.
- Create a net gain legacy. Ensure net gain generates long term benefits.
- Optimise sustainability.
- Be transparent.
Biodiversity Net Gain Strategy
Biodiversity net gain must be considered early in a project and in collaboration with the rest of the project design team which may include a landscape architect.
A biodiversity net gain strategy should include (but may not be limited to) the following documentation:
- Baseline ecology survey report including a habitat plan and habitat condition assessments.
- Landscaping proposals showing habitats to be retained, created and enhanced/restored, where applicable.
- A completed version of the statutory biodiversity metric.
- A completed version of the biodiversity gain plan template.
A 30-year Habitat Management and Monitoring Plan (HMMP) will be required for any onsite habitat creation of enhancement measures that are defined as ‘significant’. To be deemed ‘significant’ the measures must meet the following criteria:
1. Onsite creation, improvements in condition, or retention, of habitats assigned medium distinctiveness or higher in the Statutory Biodiversity Metric, will be considered as significant.
2. The onsite creation or improvement in condition of low distinctiveness habitats (excluding units delivered by vegetated gardens), will be considered significant, where either:
A. the combined number of units delivered is equal to or greater than 0.5; and/or
B. the combined number of low distinctiveness units is equivalent to 10% or more of the baseline biodiversity unit value of the site.
Where these criteria are not met, a Landscape and Ecological Management Plan (LEMP) may be required instead. These plans will usually be requested via a planning condition.
Habitat Degradation
There are special provisions for the calculation of the pre-development biodiversity value of onsite habitat when loss or impact to habitats (or ‘degradation’) has occurred prior to the submission of a planning application and Biodiversity Gain Plan in order to discourage the deliberate degradation of existing onsite habitats to reduce the pre-development biodiversity value.
Paragraph 6 of Schedule 7A of the Town and Country Planning Act 1990 states that if a person carries on activities on land on or after 30 January 2020 otherwise than in accordance with planning permission, or any other permission of a kind specified by the Secretary of State by regulations, and as a result of the activities the biodiversity value of the onsite habitat is lower on the relevant date (e.g. the date of the baseline habitat survey being undertaken) than it would otherwise have been, the pre-development biodiversity value of the onsite habitat is to be taken to be its biodiversity value immediately before the carrying on of the activities.
Paragraph 6A of Schedule 7A of the Town and Country Planning Act 1990 states that if a person carries on activities on land on or after 25 August 2023 in accordance with a planning permission, on the relevant date, development for which that other planning permission was granted has not been begun, or has been begun but has not been completed, and as a result of the activities the biodiversity value of the onsite habitat is lower on the relevant date than it would otherwise have been, the pre-development biodiversity value of the onsite habitat is to be taken to be its biodiversity value immediately before the carrying on of the activities.
Paragraph 7 of Schedule 7A of the Town and Country Planning Act 1990 states that where there is insufficient evidence of the biodiversity value of an onsite habitat immediately before the carrying on of the activities referred to in paragraph 6 or 6A, the biodiversity value of the onsite habitat is to be taken to be the highest biodiversity value of the onsite habitat which is reasonably supported by any available evidence relating to the onsite habitat.
For the purposes of submitting a planning application, where degradation activities have taken place (as listed above) before the submission of the application or an earlier proposed date, the applicant must provide:
- a statement setting out that these degradation activities have been carried out;
- confirmation of the date immediately before these activities were carried out;
- the pre-development biodiversity value of the site on this date;
- the completed metric calculation tool showing the calculations, and
- any available supporting evidence of this.
Additional Requirements
LP Ecological Services Ltd may be able to assist with the identification of potential opportunities for habitat creation, restoration and enhancement to inform biodiversity net gain requirements but is unable to offer design services in this capacity. LP Ecological Services Ltd accepts no design liability associated with habitat creation, restoration or enhancement.