Since February 2024, biodiversity net gain (BNG) regulation requires developers to ensure that most new developments result in a minimum 10% net increase in biodiversity compared to pre-development levels.
By Gwilym Jenkins, Senior Associate Director, Farming & Renewables and Kevin Hunt, Senior Director National Planning
The regulation aims to halt biodiversity loss and promote nature conservation alongside development projects, through measures such as habitat creation, restoration, or enhancement.
1. All developments requiring planning permission (unless exempt) in England are required to replace and show a minimum of 10% increase in biodiversity compared to pre-development levels.
2. The legal requirement for 10% BNG is being implemented in stages (12 February 2024 for major developments, 2 April 2024 for minor developments and 2025 for major infrastructure projects).
3. Some Local Planning Authorities are seeking and a 20% and even 30% net gain in emerging Local Plans.
4. Biodiversity is measured using a calculator provided by Natural England and must be delivered and maintained for 30 years.
Why have the regulations been introduced?
HW: Biodiversity net gain has been introduced to address the ongoing loss of biodiversity caused by human activities, such as urbanisation, agriculture, and infrastructure development. The Centre for Ecology and Hydrology recently assessed 10,000 species in the UK and found that roughly one in six are at risk of being lost. BNG regulations seek to reverse any losses, while providing a standardised metric for assessing biodiversity gains. This should be in theory make the process more transparent and accountable.
Who does biodiversity net gain apply to?
KH: Unless exempt, the BNG requirements apply to developers and landowners applying for planning permission to undertake new development projects that have the potential to impact habitats. This includes a wide range of development types across all real estate sectors, as well as infrastructure projects and land use changes.
When you apply for planning permission you’ll need to confirm whether your development is exempt from BNG and if isn’t exempt, you will need to provide information about how you intend to meet the BNG objectives. While there are a number of exemptions, in reality they are quite limited including, for example a development that does not impact a priority habitat and impacts less than:
- 25 square metres (5m by 5m) of on-site habitat
- 5 metres of on-site linear habitats such as hedgerows
A development is said to impact a habitat if it decreases the biodiversity value.
How much does biodiversity net gain cost?
HW: The cost of biodiversity net gain can vary widely depending on factors such as the scale and nature of the development project, the specific biodiversity enhancement measures required, and local environmental conditions. Initial costs will typically include baseline assessments, habitat creation or restoration, and monitoring.
However, it's important to consider the long-term benefits and potential cost savings associated with BNG, such as improved ecosystem services, enhanced resilience to climate change and regulatory compliance. Integrating biodiversity enhancement measures into development projects from the outset can often be more cost-effective than retrofitting solutions further down the line.
What happens if I can’t create the 10% net gain on site?
HW: If developers cannot achieve all their BNG on-site, they can deliver it through a mixture of on-site and off-site. Developers can either make off-site biodiversity gains on their own land outside the development, albeit the % of BNG required increases. Or - as a last resort – they can buy off site biodiversity units on the market. As a general point, there is greater risk in offsite BNG units as there could be insufficient control over the off-site BNG land to ensure the performance of monitoring and maintenance requirements over the 30-year period. Hence it is recommended, wherever possible, to secure all the BNG units on-site.
How will authorities keep track of the various commitments?
HW: For sites that can’t accommodate all their BNG requirements on site, Natural England maintains the Biodiversity Gain Site Register, which is a public record of off-site commitments agreed by developers. It remains unclear exactly how onsite delivery of BNG will be kept track of, as onsite BNG provision is not currently required to be part of the register. The Government is investigating how onsite BNG delivery details could be extracted from planning consents and made available on the register.
I am planning a new development where do I start?
KH: Firstly, in all cases developers should seek to avoid or reduce any negative impact on biodiversity through the design process. Developers then need to check if a development is exempt from BNG, and if not, it will be necessary to measure habitats and the development’s impact on those habitats and consider if BNG can be delivered on-site, or if off-site gains are required, following the biodiversity gain hierarchy.
All relevant planning applications will need to include information such as existing and proposed plans and the completed biodiversity metric calculation tool. The metric is used to calculate how many units a habitat contains before development takes place and how many units are needed to replace the units of habitat lost and to achieve 10% BNG. If this information isn’t submitted, the council may refuse to validate the planning application.
A six-step plan to meet your bng obligations on site
Creating biodiversity net gain involves six key steps:
