Updated on April 5th, 2024

What is Biodiversity Net Gain and what does it mean for development in the UK?

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Oliver Lewis

Oliver Lewis

Founder of Joe’s Blooms
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Oliver Lewis is the founder of Joe’s Blooms, providing end-to-end digital solutions to help you create best-in-class Biodiversity Gain Plans. Expert in this field, he shares his knowledge on the Environment Bill.

What is Biodiversity Net Gain (BNG)?

Biodiversity Net Gain is a sustainable approach to development and land management that intends to ensure that development projects have a positive impact on biodiversity. The idea is that any development should not just avoid harm to nature but contribute to its restoration and enhancement, leaving the natural environment in a measurably better state than it was beforehand.

    What is Biodiversity Net Gain (BNG) and why does it matter?

    Biodiversity Net Gain is a sustainable approach to development and land management that intends to ensure that development projects have a positive impact on biodiversity. The idea is that any development should not just avoid harm to nature but contribute to its restoration and enhancement, leaving the natural environment in a measurably better state than it was beforehand.

    In the new Environment Act 2021, the UK government introduced a mandatory biodiversity net gain environment bill (which became effective November 2023) making biodiversity net gain a legal requirement for all new developments in England. To secure planning permission, developers will have to submit a Biodiversity Gain Plan (BGP), assessing the habitat value of the land they will be developing and providing a measurable plan of how they will create a net uplift in biodiversity of at least 10% over a minimum period of 30 years.  

    This new approach addresses the significant and ongoing biodiversity losses, specifically those losses caused by human action. It seeks to counteract these losses by requiring that any new developments or builds improve the overall biodiversity value in existing habitats or by generating additional biodiversity gains through measurable improvements.

    How Biodiversity Net Gain will be achieved through the new Environment Bill

    Property Developers, Local Planning Authorities, and Landowners/Homeowners are required to do their bit to achieve the Biodiversity Net Gain goals as outlined in the UK’s Biodiversity Net Gain Environment Bill.

    In order to commence developments, property developers need to prove that their project will enhance biodiversity, or achieve net gain, by meeting the minimum requirements outlined in the UK's new biodiversity net gain approach (a 10% biodiversity net gain expectation over the next 30 years). Development proposals must now include a Biodiversity Gain Plan, or BGP for short. There are three avenues by which biodiversity value can be incorporated into a development proposal to meet the new requirements.

    1. Creating on-site environmental benefits that enhance the habitat value directly (preferable)

    Examples of this may be: enhancing wildlife habitats in a way that will safeguard protected species, building green infrastructure, and/or contributing to local nature recovery strategies with ecological importance. In doing so, developers will be improving air quality, providing access to green space and nature, building for flood resilience, protecting priority habitats, preserving irreplaceable habitats, incorporating ecological features into future developments, and many other environmental management benefits to improve biodiversity!

    1. Registering an off-site net gain that has been allocated and approved as part of the development project (acceptable in the case it is not possible to create biodiversity net gain on-site)

    This off-site property can be owned by the developer or permitted for use by a separate landowner. Examples listed in the on-site habitat biodiversity gain options above would also apply to these off-site allocations.

    1. Obtaining statutory biodiversity credits from the Secretary of State in accordance with the environment bill requirements (not preferred and only applicable in special cases)

    This third option has been established as a last resort to reach biodiversity net gain mandates in the case developers are unable to achieve biodiversity net gain minimum requirements on-site or off-site.  

    To create biodiversity credits, the UK government will establish biodiversity enhancements throughout the country, all focused on delivering biodiversity net gain. Every enhancement project or land parcel will have a biodiversity value or “credit”. These biodiversity credits may then be purchased as part of a Biodiversity Gain Plan to deliver net gain minimums.

    All payments from biodiversity credits to the Secretary of State will be utilised solely for the purpose of habitat enhancement. This can include acquiring land interests, carrying out necessary works, and covering operational and administrative expenses associated.

    Local Planning Authorities have the legal obligation to assess the Biodiversity Gain Plan (in addition to all other required documents) as a part of the approval process to grant development permissions. As the planning authority in each local council, it is their responsibility to prevent biodiversity loss for all new and future developments. To this end, it’s important that they know how to “measure biodiversity” and can accurately evaluate how new developments will be delivering net gain on and off development sites.

    Landowners and homeowners have the opportunity to assess their property for its habitat value, offering off-site biodiversity units that developers may purchase in cases where they are unable to meet the minimum biodiversity net gain on-site.

    BNG principles for development

    Beyond merely offsetting losses, Biodiversity Net Gain aims to prevent further biodiversity loss by preserving local habitats, engaging stakeholders, and aligning with local and national conservation aims. Maintaining and reversing biodiversity loss will require massive collaboration. To facilitate these underlying goals, the following 10 principles have been developed by CIEEM, IEMA and CIRIA to ensure a comprehensive and effective approach to achieving sustainable and meaningful Biodiversity Net Gain.

    1. Apply the Mitigation Hierarchy: Prioritise avoiding environmental harm, followed by minimising impacts, then remediation. Where harm is unavoidable, compensate through environmental enhancements.

    1. Avoid losing irreplaceable biodiversity: Protect habitats and species that cannot be replaced or replicated elsewhere.

    1. Be inclusive and equitable: Involve and consider all stakeholders, ensuring fair distribution of environmental benefits and burdens.

    1. Address risks: Anticipate and manage potential negative impacts on biodiversity throughout the project lifecycle.

    1. Make a measurable Net Gain contribution: Quantify improvements in biodiversity, ensuring gains outweigh losses.

    1. Achieve the best outcomes for biodiversity: Aim for high-quality, sustainable ecological improvements that support a diverse range of species and habitats.

    1. Be additional: BNG initiatives should enhance, not replace, existing biodiversity commitments and regulations.

    1. Create a Net Gain legacy: Develop long-term, sustainable benefits for biodiversity, leaving a positive impact for future generations.

    1. Optimise sustainability: Integrate BNG with broader environmental sustainability goals, creating synergy between biodiversity and other ecological targets.

    1. Be transparent: Maintain openness in all BNG processes and decisions, ensuring accountability and public trust.

    Key components of mandatory Biodiversity Net Gain

    The Environment Act 2021 mandates the key components for Biodiversity Net Gain for all new developments (with very few exceptions). It revises the Town & Country Planning Act originated in 1990 and stipulates the following requirements:

    • Minimum Biodiversity Gain: A mandatory increase of at least 10% in biodiversity is required, with this gain quantified using the established Biodiversity Metric (the Government can change the percentage if it wishes).

    • Long-term Habitat Protection: Newly developed habitats must be safeguarded for a minimum duration of 30 years. This protection is ensured through planning obligations or conservation covenants.

    • Flexible Achievement of Biodiversity Net Gain: The strategy for achieving Biodiversity Net Gain is flexible, allowing for implementation either on-site, off-site, or through a statutory biodiversity credits scheme - though, in accordance with the mitigation hierarchy, restorative work should always be as close as possible to the point of impact.

    • National Register and Existing Protections: The Act introduces a national register for tracking net gain delivery sites.

    • Retention of Current Legal Protections: The Act maintains existing legal safeguards for key habitats and wildlife species, ensuring that these areas continue to receive the protection they currently enjoy.

    • Adherence to Mitigation Hierarchy: As noted above, a clear emphasis is placed on following a mitigation hierarchy. This involves a prioritised approach where the first step is to avoid environmental impacts. If avoidance is not possible, the next step is to mitigate these impacts. Compensatory measures are considered only as a last resort.

    • Scope of Application: The Act's provisions are applicable to many types of development including Nationally Significant Infrastructure Projects (NSIPs).

    The sooner the better - why getting involved with Biodiversity Net Gain now is valuable

    Councils and many developers are already gearing up for the impending legal requirements of Biodiversity Net Gain, and there are numerous advantages to staying ahead of the legislation. Understanding and integrating Biodiversity Net Gain into current and future projects not only provides a head start in complying with future legislation but can also aid developers in better managing and coordinating their projects in line with local conservation efforts and evolving requirements.

    Beyond policy compliance, Biodiversity Net Gain is an opportunity for councils to think holistically, linking Biodiversity Net Gains with broader council services. For councils that have declared a climate and ecological emergency, Biodiversity Net Gain offers a tangible action to address these crises. It's a chance to envision and shape the future natural environment of local areas, ensuring it delivers for the community.

    Local Nature Recovery Strategies (LNRS) are another critical aspect. They offer an opportunity for collaborative work with neighbouring authorities’ reach beyond local government to involve communities, landowners, developers and farmers in creating and reaping the benefits of Biodiversity Net Gains, particularly when it comes to biodiversity units (BUs) in the off-site BU credit market.

    Engaging with Biodiversity Net Gain now also allows for input into ongoing policy development by Defra and Natural England. Early adoption of  Biodiversity Net Gain practices can inform policy and legislation, making them more effective and applicable.

    Who is exempt from Biodiversity Net Gain?

    The UK Government has listed a small number of exemptions from the Biodiversity Net Gain (BNG) rules. However, it’s worth saying that these exemptions are few and far between - BNG is intended to be a universal policy, and it’s always better to err on the side of complying than trying to avoid. That said, let’s look at the exemptions: 

    De Minimis Threshold: Designed for the smallest of projects, if a development impacts no priority habitat and less than 25 square metres of non-zero rated habitat, or less than 5 metres for linear habitats like hedgerows and watercourses, it will fall below the 'de minimis' threshold and will be exempt from BNG. However, you must demonstrate that you are genuinely eligible to meet the de minimis threshold and the Local Planning Authority will inspect any claim to ensure that there is no fraudulent attempts to sidestep the new obligations. 

    Householder Applications: Development related to household applications also falls under the exemptions. Of course, you can always undertake BNG anyway or there are a number of other things you can do to increase biodiversity in your home.

    Self-Build and Small-Scale Developments: Small scale self-build and custom housebuilding projects are included in the exemptions, however you must make sure that you meet the specifications set out in the relevant laws. 

    Biodiversity Gain Sites: Sites specifically enhanced to benefit wildlife, termed biodiversity gain sites, are exempt (these sites are already geared towards enhancing biodiversity, they are not subject to additional BNG requirements). 

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