Biodiversity Net Gain is a forward-thinking conservation approach that seeks to enhance the overall biodiversity in a given area as a result of development projects.

Instead of merely mitigating the negative impacts of development on the environment, Biodiversity Net Gain focuses on achieving a quantifiable increase in biodiversity by ensuring that an area's ecological value after development is higher than its value before the project began.

On the 27th of September, the Government set out the next steps on plans for new housing, commercial and infrastructure developments to be nature-positive by confirming that upcoming legislation to bring in these rules will be laid in November this year.

Environment Act 2021: A Milestone

The Environment Act 2021 encapsulates the UK government's commitment to environmental protection.

One of its pivotal clauses introduces the concept of mandatory biodiversity net gain for new developments. 

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What is biodiversity net gain

Components of Biodiversity Net Gain Requirements

Biodiversity Net Gain requirements involve several key components that collectively aim to ensure that development projects positively impact biodiversity and ecological systems.

Biodiversity Gain Plan 

To implement Biodiversity Net Gain effectively, developers must conduct a thorough baseline assessment of the site's existing biodiversity.

This assessment serves as a reference point against which the post-development biodiversity will be measured. 

Biodiversity Metric and Minimum Net Gain Percentage 

The implementation of Biodiversity Net Gain hinges on accurate assessment.

A standardised biodiversity metric is employed to gauge the biodiversity value of a site before and after development. The metric uses habitats as a proxy for biodiversity value.

It does not address impacts on species, nor recognise the significance of site designations, or take account of indirect impacts, cumulative impacts, or in-combination impacts. 

By comparing the pre-development baseline and post-development scenario, the metric can, therefore, assess how a development will impact the biodiversity value of a site.

The biodiversity gain objective is met if the biodiversity value attributable to the development exceeds the pre-development biodiversity value of the onsite habitat by at least 10%. 

Biodiversity Offsetting

Developers are encouraged to follow a hierarchy of mitigation measures to avoid, minimise, restore, and offset impacts to biodiversity. Avoiding or minimising impacts to biodiversity should be prioritised. 

In some cases, it may be challenging to achieve net gain on the development site itself.

Biodiversity offsetting enables developers to impair the habitat value of a site, provided they pay to restore another habitat site that has the potential to become at least the same quality as the habitat that will be lost. 

Securing Biodiversity Net Gain 

Significant increases in onsite biodiversity value can only be considered by the local planning authority as part of the post-development biodiversity value if they are secured through a suitable mechanism such as a planning condition or section 106 agreement and will be maintained for at least 30 years after the completion of development.

In order to secure off-site gain, the biodiversity gain site register is used. The core purpose of the register is to record allocations of off-site biodiversity gains to developments and make this information publicly available.

Biodiversity gain sites are sites that are bound by a planning obligation or conservation covenant, which requires habitat enhancement works to be carried out on the land and maintained for at least 30 years following completion. 

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Components of Biodiversity Net Gain Requirements

Navigating Biodiversity Net Gain Compliance

Developers need to start engaging with their new Biodiversity Net Gain compliance obligations and will need to consider their strategy for achieving Biodiversity Net Gain in the short and longer term.

There are several complex legal documents required to secure Biodiversity Net Gain enhancement, such as section 106 agreements and conservation covenants, as well as unilateral undertakings.

Accordingly, there is a need for extensive due diligence around these documents.

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Navigating Biodiversity Net Gain Compliance

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If you need professional legal advice regarding Biodiversity Net Gain compliance, please contact Myerson Solicitors' Commercial Property team on:


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Emily Sutherland

Senior Associate

Emily has 7 years of experience acting as a Commercial Property solicitor. Emily has specialist expertise in real estate commercial matters, including landlord and tenant work, acquisitions and disposals, property development and finance.

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