Guide to biodiversity net gain for development and land management

Published: 16 February 2023
Last updated: 2 February 2024

While some organisations have embraced their biodiversity net gain responsibilities, others are just beginning their net gain journey.

Let our experts guide you through the process, offering targeted advice to secure planning approvals, prevent project delays, and help you realise the benefits of biodiversity net gain.

What is biodiversity?

The word biodiversity is a combination of the words 'biological’ and ‘diversity'.

Biodiversity is all the different varieties of life found in a particular area. These could be animals, plants, fungi, and bacteria. Each of these species and organisms work together in ecosystems to maintain balance and support life. Humans rely on biodiversity to survive because it is what gives us food, clean water, medicine, and shelter.

What is biodiversity net gain?

Biodiversity net gain (BNG) is an approach to development and land management that aims to leave the environment in a better condition than before.

The construction of homes, businesses, and infrastructure has traditionally damaged habitats and depleted the environment. Biodiversity net gain is designed to reverse that harm, requiring developers to create or enhance habitats and boost biodiversity as part of each project. Such improvements can be delivered onsite, offsite, or through a combination of solutions.

The Environment Act 2021 means that all planning permissions granted in England must provide at least 10% biodiversity net gain from January 2024. The law applies to developments that impact urban and rural spaces, hedgerows, linear areas such as roads and railway tracks, and aquatic environments like rivers and streams.

For each development, a biodiversity net gain plan will be needed for local authority approval. This should cover:

Current habitat conditions, based on ecological assessments
Strategies for increasing biodiversity by at least 10%
Methods of measuring and maintaining improvements for 30 years

Get early support to assess site condition for biodiversity net gain

Biodiversity net gain considerations begin well before the submission of your planning application. Working with a trained ecologist at site selection stage builds in biodiversity goals from the outset, keeps timelines on track, and prevents problematic investments.

Biodiversity net gain is determined using Defra’s biodiversity metric, a habitat-based approach that evaluates an area’s value to wildlife.

To analyse your starting point, your ecologist will conduct a range of assessments to gauge your site’s overall condition. They’ll take into consideration:

Size – How much area does the habitat cover?
Condition – Is the habitat poor, moderate, or good?
Distinctiveness – Is the habitat ecologically important in any way?
Strategic significance – Is the habitat a local priority or earmarked for enhancement?

Using the onsite survey results, your environmental partner will calculate the site’s biodiversity unit value before development and its projected value post-project. This helps you plan your route to 10% biodiversity net gain and the ideal onsite and/or offsite measures to achieve it.

Collaborate on your biodiversity net gain plan

If your planning application is subject to mandatory biodiversity net gain requirements, you’ll need to provide a biodiversity net gain plan for approval by your local authority. Based on the outcome of your initial habitat surveys, the document outlines your strategy for delivering 10% net gain and sustaining improvement levels for the next 30 years.

Even if your business employs in-house ecologists, it pays to collaborate with an external specialist. A trusted partner provides independent validation of your proposal and offers an industry-wide perspective of best practice.

Your net gain plan will include recommendations based on three government-approved options:

Onsite solutions – Ideally, you will generate your 10% net gain by enhancing existing habitats or creating new ones within your site’s red line boundary. This might involve landscaping, planting trees, or sowing grass seed or wildflowers
Offsite solutions – If your site allows minimal or no biodiversity net gain opportunities onsite, you’ll need to explore remote alternatives. This involves paying to establish or upgrade habitats elsewhere in the local area. Example projects include habitat banks, rain gardens, or grasslands maintained by public or private landowners within the borough. Land used to deliver offsite biodiversity net gain programmes will need to be secured for a minimum of 30 years
Statutory biodiversity credits – This ‘exchange system’ lets you purchase biodiversity credits that can be used to deliver large-scale habitat projects when 10% biodiversity net gain can’t be achieved onsite. For example, a business might use credits to convert a farmer’s field into a wildflower meadow to meet biodiversity net gain targets on a nearby development. Similarly, developers who exceed biodiversity net gain requirements on one project could use excess credits to offset deficits on another

Working in line with the current biodiversity net gain framework, your consultant will produce an ecological management plan – incorporating onsite, offsite, or credit strategies – that delivers 10% net gain within the limitations of your site.

An experienced advisor will liaise with county ecologists and planning authorities to shape commercially viable solutions that balance business and biodiversity needs.

They’ll also map out a management, monitoring, and reporting programme that locks in compliance across the required 30-year period.

If credits are recommended, your ecologist can also act as an independent broker, ensuring offsite spaces provide value for money and the potential to create a sustainable habitat.

Getting the most from your biodiversity net gain strategy

The earlier you factor biodiversity net gain targets into future developments, the more successful and streamlined your projects will be.

Here are our expert pointers on simplifying the biodiversity net gain process:

Partner with an ecologist now – Carry out your ecology survey as early as possible to keep projects on schedule and design in biodiversity net gain targets from day one. You need to achieve 10% net gain across all habitats present on your site – including woodland, hedgerows, and aquatic systems – so don’t forget to include below-water environments in your assessment
Clarify your red line boundary – To avoid extra costs and inaccuracies, pinpoint the area you’re measuring and monitoring before your surveys begin
Assess at the right time – Schedule your assessments during optimal conditions. This is generally spring or summer, when vegetation and protected species are present
Understand your ideal options – Not all solutions work for all sites. For example, planting trees near an airport can increase the risk of bird strikes. Working with a skilled ecologist will identify the most effective biodiversity net gain plan for your development
Create a joined-up supply chain – Everyone has a role to play in delivering net gains – from landowners to local authorities and customers to contractors. If you’ve set biodiversity net gain targets for your business, give your suppliers the tools, time, and information to understand and achieve them. Similarly, if you’re working on behalf of a client, be ready to adopt their biodiversity net gain requirements as your own.
Take a big picture view – Ecological surveys investigate surrounding habitats. Use this information to explore collaborative biodiversity opportunities with neighbouring landowners and developers. Could you join forces to spread costs, exceed targets, and create complementary habitats?
Plan for increased accountability – Penalties are likely to spiral for causing environmental harm to nearby land that’s actively driving biodiversity net gain. Strengthening your pollution and spill prevention plans will reduce your liability risks
Tap into biodiversity net gain's PR value – Biodiversity efforts are key to tackling climate change – and earning the confidence of environmentally aware consumers. Showcase your biodiversity net gain projects to demonstrate progress and quantify your commitment to positive change

Biodiversity net gain informs almost every planning decision in England. so it is essential to build biodiversity net gain into every project. Placing an ecological expert in your corner will ensure you remain on the right side of evolving regulations.

Questions about your biodiversity net gain options? Speak to our experienced ecology team.