Currently, public authorities in England and Wales are under a duty to have regard to the purpose of conserving biodiversity (endnote 1) in the exercise of their functions. This duty is intended to embed consideration of biodiversity in policy and decision making (including planning decisions), throughout the public sector which should be seeking to make a significant contribution to the achievement of the commitments made by government in its 25 Year Environment Plan.

The Environment Bill, which is making its way through Parliament, includes a strengthening of the existing duty on public authorities to conserve biodiversity. The Environment Bill also contains a specific duty on all public authorities to "have regard" to relevant Local Nature Recovery Strategies (LNRS) (see further below), and a duty for specified public bodies to report every five years on what action they have taken.

Biodiversity Net Gain (BNG) describes the process by which new development may increase the levels of biodiversity present on a site, where biodiversity is the variety of plant and animal life in a particular habitat.

What does policy state?

National policy sets out that planning should provide BNG where possible. The recently revised National Planning Policy Framework (NPPF) July 2021 in paragraphs 174(d), 179(b) and 180(d) refers to this policy requirement. The natural environment planning practice guidance provides further explanation on how this should be done (endnote 2).

In particular the revisions to the revised NPPF include changes to paragraph 180(d) which now states that:

"d) development whose primary objective is to conserve or enhance biodiversity should be supported; while opportunities to improve biodiversity in and around developments should be integrated as part of their design, especially where this can secure measurable net gains for biodiversity or enhance public access to nature where this is appropriate." (Words in italics were added as part of the July 2021 NPPF update).

The Government's 25 Year Environment Plan (2018) sets out the aspiration to expand the net gain approaches used for biodiversity to include wider natural capital benefits, such as flood protection, recreation and improved water and air quality. 

The BNG must be measured using a recognised biodiversity metric - which calculates biodiversity value (in units) before and after development - and Natural England published its new Biodiversity Metric 3.0 on 7 July 2021. This will provide a way of measuring and accounting for nature losses and gains resulting from development or changes in land management.

Also announced was the Small Sites Metric (SSM), a beta version, designed to simplify the process of calculating BNG on smaller development sites.

Mandatory BNG to be introduced by the Environment Bill

At the end of 2018 Defra consulted on BNG and before the outcome of the consultation was published, the government announced, in the Spring Statement 2019, that it would make BNG mandatory for development by bringing forward provisions to that effect in the Environment Bill.

The Environment Bill contains a general duty to enhance biodiversity which will apply to the planning system by insertion of a new section 90A within the Town and Country Planning Act 1990 (TCPA), and following government amendments agreed in June to projects under the 2008 Act regime (endnote 3). The provisions are unlikely to become law before 2023.

The new section 90A TCPA will make it a requirement that all planning permissions in England be subject to a condition to ensure the biodiversity value attributable to the development exceeds the predevelopment value by at least 10% - the biodiversity gain objective (BGO). The biodiversity value of a development will be measured using the DEFRA metric.

In summary, the Bill provides that components to mandatory BNG will include the already mentioned minimum 10% gain and approval of a net gain plan. Habitat will need to be secured for at least 30 years via obligations or a conservation covenant. Delivery of BNG may be on-site, off-site or via statutory biodiversity credits and there will be a national register for BNG delivery sites. The mitigation hierarchy will continue to apply and there will be no change to existing legal environmental and wildlife protections.

Environment Bill progress through Parliament

The Environment Bill was introduced to Parliament on 30 January 2020. The pandemic has delayed the bill's progress. Royal Assent is now anticipated in Autumn 2021 and a two year transitional period will follow to allow for accompanying regulations and guidance to be produced to provide further detail on how the provisions will be implemented. The currently estimated dates for introduction of mandatory BNG are indicated below, but are heavily dependent of the bill's Parliamentary progress.


  • Summer: new British Standards Institute (BSI) BS 8683:2021 BS 8683 Process for designing and implementing BNG – Specification
  • Autumn: Royal Assent for the Environment Bill and a consultation on BNG statutory instruments and regulations is expected.


  • Spring: Government response to consultation expected.


  • Spring: BNG site register and statutory credits sales platform
  • Autumn: BNG expected to become mandatory for all TCPA (and planning Act 2008) developments.

Matters to consider

When bringing forward sites, consideration will need to be given to how the necessary BNG will be delivered and secured in the planning process in a way that will meet the BGO and the Environment Bill sets up this framework.

In practice, compliance with the provisions, is likely to involve a pre-commencement planning condition requiring a 'biodiversity gain plan' to be submitted for approval by the LPA and setting out how the gains will be obtained, monitored and maintained on an ongoing basis for at least 30 years (endnote 5).

The Environment Bill will allow for the BGO to be achieved by delivering BNG not on the development site itself. Offsite gains may be counted provided they are secured via a planning obligation and recorded in the new BNG site register. The section 106 mechanism could be used in circumstances where land is owned or controlled by the Council and where it may accept a commuted sum secured via the agreement and that it then uses to deliver the suitable compensatory habitat. The Environment Bill also introduces a new statutory covenant between a landowner and a 'responsible body' (Secretary of State, local authority or conservation organisation), imposing positive or negative obligations on either or both parties. Such conservation covenants will be binding on successors in title and will be enforceable by the responsible body and the landowner against each other.

Note that the NPPF states that agreeing conditions early is beneficial to all parties involved in the process and that it can speed up decision-making. It will advisable for applicant's to turn their mind to delivering BNG early in the development design and planning process.

To provide some assistance with this, Natural England, published on 7 July 2021 the Environmental Benefits from Nature Tool (EBNT) to give developers a way of exploring the benefits habitats bring to people, such as improvements to water quality, flood management services and carbon storage.

CIEEM, IEMA and CIRIA have set out good practice principles for development and an associated practical guide and case studies for BNG.

CIEEM have also published Biodiversity Net Gain report and audit templates that provide a framework for writing reports for projects that are aiming to achieve BNG. The templates set out a suggested structure and content for reports specifically produced in relation to BNG assessments.

What is next?

The creation of LNRSs was announced in government’s response to the 2019 public consultation on net gain which revealed strong support for maps to guide the provision of compensatory habitat. 

LNRS are a part of an ambitious package of measures being introduced by the Environment Bill to reverse nature's decline. Environmental Improvement Plans and legally-binding targets, including the additional target for species abundance for 2030, will establish long-term policy direction. BNG is mechanism to drive investment in nature from the development sector and the strengthened "biodiversity duty" will make sure the public sector plays a leading role. Government intends for LNRS to work with all of the measures and to help link them together in a coherent and effective way. 

A key purpose of LNRS is to provide a consistent spatial planning framework for the creation of the Nature Recovery Network. The Environment Bill specifies two components a LNRS must contain; a statement of biodiversity priorities and a local habitat map. The strategies are intended to map the most valuable existing habitat for nature in a given area; map specific proposals for creating or improving habitat for nature and wider environmental goals; and set agreed priorities for nature's recovery. 

Once the Environment Bill becomes law, government will issue regulations and statutory guidance to ensure consistent implementation of LNRS across England. To this end Defra published a consultation on 10 August 2021 on LNRS which is open until 2 November 2021 (endnote 4). The first group of consultation questions are on how LNRS should be prepared, published, reviewed and republished. The second set of questions are on content of the strategies and which will be subject of statutory guidance in due course.

As set out above, the Environment Bill ensuring that delivering BNG becomes a mandatory part of the development process. When a development is not able to accommodate the required increase in biodiversity on the development site itself, off-site habitat enhancement will be required. Natural England's biodiversity metric 3.0 includes a 15% uplift in units generated in locations proposed by the LNRS to encourage developers to focus on these places where the benefit will be greatest.

The Defra consultation states that government is keen for LNRS to be in place across England as soon as possible after the bill becomes law. The Environment Bill's next stage will be the House of Lords report stage due to take place 8, 13, and 15 September. This will be followed by Third reading, ping pong and Royal Assent expected for early Autumn.


(1) Section 40 of the Natural Environment and Rural Communities Act 2006; Natural Environment and Rural Communities Act 2006 (

(2) Delivering net gain is also referred to in the National Infrastructure Commission's Design Principles, National Policy Statements and the National design guide.

(3) Following government amendments agreed in June 2021, the Environment Bill's mandatory BNG requirements will also apply to Nationally Significant Infrastructure Projects consented under the Planning Act 2008 regime.

(4) Local Nature Recovery Strategies: how to prepare and what to include - Defra - Citizen Space

(5) Paragraph 13 of Schedule 7A. Clause 90 and Schedule 14 of the Environment Bill insert a new section 90A and Schedule 7A into the TCPA 1990. 

This article is for general information only and reflects the position at the date of publication. It does not constitute legal advice.