Biodiversity Net Gain

On 4 June 2020 our Planning & Environment team hosted a webinar to look at the Government’s proposals in the Environment Bill for mandating biodiversity net gain for new developments.  Here we summarise the main issues that were discussed and give our thoughts on how the proposals might work in practice when (and if) they are implemented.

What is the current legal and policy position?

  • LPAs are currently subject to duties under the Natural Environment and Rural Communities Act 2006. They must have regard to the purpose of conserving biodiversity (which includes restoring or enhancing a species or habitat).  This is difficult to enforce, as they only need to consider the duty.
  • The Environment Bill is going to strengthen the aspects of that duty that deal with enhancing biodiversity, which is part of a consistent theme running through the Bill of improving (rather than just conserving) the environment.
  • NPPF requires policy and decisions to contribute to and improve the natural local environment and minimise impacts. Requires LPAs to refuse applications if deemed harmful to biodiversity if the harm cannot be avoided through relocation, mitigation or compensation (but only as a last resort). Those developments that promote biodiversity are to be encouraged.
  • Planning Practice Guidance says net gains can be secured on site, off site or a combination of the two, through planning conditions, planning agreements or unilateral undertakings.
  • The effect of the Bill is to take the existing policy and guidance on biodiversity and turn them into statute.

What do the main provisions in the Environment Bill cover?

  • Key parts of the Bill dealing with biodiversity net gain (or ‘biodiversity gain’, as it is called in the Bill) are clauses 90 to 94 in Part 6 and Schedule 14.
  • It provides the Secretary of State with a number of powers, including power to set up a register of biodiversity gain sites (clause 91) and the ability to sell biodiversity credits to developers (clause 92).
  • Clause 93 amends the duty in the Natural Environment and Rural Communities Act (as outlined above) and requires public authorities to have regard to enhancing biodiversity as well as conserving biodiversity.
  • Schedule 14 provides the detail of biodiversity net gain and adds a new Schedule 7A into the Town and Country Planning Act 1990.
  • The biodiversity gain objective is that the post-development biodiversity value of the development must exceed the pre-development biodiversity value by at least 10%. This figure can, however, be amended by secondary legislation.
  • The biodiversity value of a site is calculated using the biodiversity metric produced and published by the Secretary of State. Currently this is version 2.0 published by Natural England and is due to be updated by December 2020.
  • If planning permission is granted by the LPA, then the pre-development biodiversity value is assessed on the date of the application. If planning permission is granted on appeal, then the value is assessed on the date permission is granted.
  • Anti-avoidance provisions must also be considered. Any activity carried out since 30 January 2020 that reduces the biodiversity value of a site will be disregarded, except when carried out in accordance with a planning permission or other permission specified by the Secretary of State in regulations.

Where do we think the Environment Bill is going to end up?

  • Currently the Bill is in its Committee Stage in the House of Commons, which it is due to complete by 25 June. There have been no oral evidence sessions on the biodiversity provisions in the Bill, though the Committee has been considering written submissions. Given the size of the Government majority in Parliament it is unlikely that any significant changes will be made. Once Royal Assent is granted, the biodiversity provisions will need to be brought into force by the Secretary of State and currently there is no timetable in place for this.

Securing biodiversity net gain

  • Net gain will be secured by a new deemed planning condition requiring a biodiversity gain plan. This will apply to all planning permissions.
  • There is a mitigation hierarchy in respect of BNG but the Government preference is on-site provision.  Off-site mitigation and the purchase of government credits are alternatives if this is not possible
  • The means of securing the implementation of the plan can be flexible – through a planning condition, s106 agreements, or a conservation covenant.
  • The bill sets out that permitted development, sites comprising of only buildings and sealed surfaces, and NSIPs are exempt

Conservation covenants. What they are, how will they operate and their likely application

  • Agreements which have particular functions conferred on them by statute, similar to s106 agreements.
  • Designed to secure conservation objectives. The conservation purpose may be ecological (and will be if the covenant is for BNG purposes) but can also be for an archaeological, architectural, artistic cultural or historic purpose and can include preserving the setting of land.
  • Will be between a land owner and a responsible body to be designated by the Secretary of State (charities, local authorities etc.)
  • Covenants will be registerable as a local land charge. They will bind the land, but owners can be released from obligations once they part with their interest in the land.
  • Can bind land in perpetuity or can be time limited. For the project to be accepted for the purposes of registered off-site biodiversity gain in connection with development the covenant will need to last for at least 30 years
  • Remedies for breach similar to those in contract, including specific performance, injunction and damages. A circumstance beyond the control of the parties or an emergency will provide the basis of a defence in relation to a failure to perform (e.g. wildfires, flooding etc.).


  • Very similar to s106 Agreements. We therefore expect LPAs to mainly deal with off-site net gain through s106 and not conservation covenants where the off-site land is within the LPA’s area.
  • May be used where the off-site net gain is distant from the main development site and outside LPA area. There would still however need to be a link between the two sites (perhaps secured through planning conditions and a side agreement between the landowners).
  • If there is to be a combination of on-site and off-site net gain and both a s106 and conservation covenant is required, this may cause additional delay as two documents to be negotiated.


  • Need for careful attention to any works that proceed on site to deal with biodiversity value in advance or without planning permission. What does this mean for standard husbandry management of sites? Regulations are likely to allow for normal land management regimes.
  • Government wants to see BNG outcomes maintained for 30 years and will encourage longer term protection.
  • Gains can be delivered through improving existing site biodiversity, or utilising land off site. If neither on-site or off-site are achievable there is the option to pay a tariff.
  • Challenge is existing metrics/bio plans in place across different LPAs. Not one size fits all and there is a requirement for pragmatism.
  • Look at what’s happened before on SANG sites for potential solutions.
  • Work with LPA and an experienced ecologist to establish base line and potential for gain.  Set clear requirements for what must be achieved and how this is to be monitored.
  • Low-quality off-site land might offer opportunity for credible improvement, if gain cannot be achieved on development site. Try to avoid third party land which might prove expensive and involve complex negotiations.
  • Land owners may wish to appoint a land trust who have experience in land management, but if developers can manage their own land then this might be preferable for overall control.

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This information is for educational purposes only and does not constitute legal advice. It is recommended that specific professional advice is sought before acting on any of the information given. © Shoosmiths LLP 2024.

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