Biodiversity Net Gain Assessment

Before the local planning authorities will consider an application for planning permission on a proposed development site, a biodiversity net gain assessment will be needed, followed by a BNG plan.

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What Goes Into Biodiversity Net Gain Assessments

Originally intended for release in November 2023 following a two-year transition period, biodiversity net gain (BNG) was a policy that featured within the Environment Bill. Once the Bill was given royal assent, it became the Environment Act 2021, and BNG quickly became an important part of planning that would see a development subject to scrutiny if there were no signs of consideration towards the environment.

To measure biodiversity and initiate a net gain of at least 10%, biodiversity net gain assessments need to be conducted, leading to the production of a biodiversity net gain plan. Not only that, but they must retain the condition of existing habitats and promote the creation of new habitats for a minimum of 30 years, improve the standard of biodiversity to a measurably better state, and operate within a national approach that is upheld by the local authorities.

In order for biodiversity net gain to be successful in any development, it also needs to pass the standards set by the National Planning Policy Framework (NPPF) and the Town and Country Planning Act 1990, and the regulations in place from the Chartered Institute of Ecology and Environmental Management (CIEEM), the Department for the Environment, Food and Rural Affairs (DEFRA) and Natural England.

Reasons for Biodiversity Net Gain Surveys

More than any other reason, the primary purpose of delivering net gain from the perspective of a developer is to ensure that the BNG requirements of the local planning authorities have been met and remain within the parameters that would otherwise see their actions harm local biodiversity.

On top of the fundamental legal obligation that stands firm as the developer’s responsibility to nature conservation and habitat enhancement, other reasons to deliver net gain for development projects may include:

  • Amassing Data
  • Contributing to Conservation Targets
  • Demonstrating Risk Management
  • Evaluating Harm to the Environment and Individuals
  • Gauging the Value of a Site
  • Mitigating Environmental Impact
  • Optimising Planned Development Works
  • Promoting Sustainable Development
  • Recording Ecological Features
  • Supporting Various Social and Economic Benefits

Working a BNG Assessment Into Your Development Plans

From the point of it becoming a legal requirement for most developments as of February 2024, a person submitting a planning application to the local planning authority would first need to achieve biodiversity net gain. The planning policy now applies to a higher percentage of both major development and non-major development projects across England, with only a few exemptions under specific circumstances.

A part of the planning process that developers are now ordered to cater to is the act of supplying evidence that mandatory biodiversity net gain has been integrated into the proposed development. It is only possible to deliver BNG correctly by providing the local authorities with a biodiversity net gain plan, and the plan itself will be created as a result of a dedicated assessment.

BNG Survey Process

Over the course of a desk study and field survey, a biodiversity net gain assessment enables an ecological consultant to account for existing habitats, determine any predicted habitat loss based on the plans of the development, and propose sufficient steps to increase the biodiversity value, assist the natural environment and adequately meet the BNG objective.

Steps in BNG Assessments

In a technical consultation of a development site to achieve BNG, stages in the process are likely to include:

Project Overview

Before the ecologist carries out any other task, the priority will be on forming an understanding of the development proposal. Key components include the aims of the planning project, the size of the site, and the scale of the development.

The data recovered will also highlight any expected adverse impacts on the actions of other stakeholders, ongoing conservation covenants, each irreplaceable habitat, sites of special scientific interest (SSSI), and if any active local lists or existing local policies apply.

Data Collection

During an extensive physical inspection of the site, the ecological surveyor will identify, record and analyse all animal and plant habitat types situated within the red-line boundary. At this point, protected species of flora and fauna will be a priority.

Using the metric designed for the measurement of biodiversity value, each listed species, on-site habitat, habitat parcel or other ecological assets such as trees, hedgerow units or watercourse units will be converted into a biodiversity unit through the statutory biodiversity metric calculation tool to create a pre-development unit value.

Impact Assessment

With data from the site recorded and an accurate biodiversity net gain metric created, it will be possible to recognise how much the development project could pose negative impacts on the local area and wider biodiversity as a whole.

Based on the DEFRA biodiversity metric tool and the plans of the development, the existing value of the site can then predict the expected biodiversity losses, as well as any potential biodiversity gains as a result of the project and the impact it has on natural habitats.

Mitigation and Compensation

A mitigation hierarchy exists to avoid losses of high-value habitats in a wide range of ecological surveys. It is also utilised in a biodiversity impact assessment, as it will assist with efforts to eliminate an unnecessary net loss of biodiversity and reach the enforced BNG outcome.

As for the biodiversity net gain approach, the hierarchy features the same core steps of avoidance, minimisation, restoration and offsetting. Any ecological consultants visiting a site will prioritise avoiding intervention with elements of relative biodiversity value in the biodiversity gain hierarchy, before moving to minimising impact, restoring impacted habitats, and providing offsite compensation elsewhere.

Enhancing Biodiversity

Part of delivering biodiversity net gain is offering adequate land management to ensure that any habitat lost is compensated for and the ecological surveyors assembling the biodiversity gain plan enhances existing habitat and creates new habitat wherever possible.

Between habitat creation, restoration and enhancement such as hedgerow or tree planting, referring back to the aims of local plans and efforts to combat climate change, areas of local importance and strategic significance and other land considerations involving modified grassland, green infrastructure and linear habitats, the ecologist can use an array of different approaches to provide net gains.

Calculating Ecological Value

After ecological surveyors have put together a full understanding of the minor development or major development they’re working on, performed a complete assessment of the site, development process and onsite habitat, used biodiversity metrics to calculate biodiversity net gain, and highlighted the positive or negative impact on biodiversity, it will be clear to see what’s needed to meet the planning obligations.

Under the legal requirements of the UK government, developers are legally required to enhance biodiversity by 10%, but it could vary depending on the local authority in question. The DEFRA metric will show an accurate pre-development biodiversity value and a predicted post-development biodiversity value, with both compared to eliminate any deficit and increase biodiversity by the 10% requirement.

Off-Site Biodiversity Gains

Once all data has been retrieved, it will be evident if it is viable to make a meaningful contribution to the environment and a sufficient increase in biodiversity. Meeting the planning obligation and seeing the statutory requirements achieved on-site will always be seen as the ideal outcome, but if it cannot be done, off-site gains can be acquired elsewhere by buying statutory credits on more suitable sites chosen through careful site selection.

Instead of being stuck dealing with just one site, a biodiversity gain site register lists countless individuals who own land for off-site biodiversity. For it to work, the developer would purchase the same quantity of off-site biodiversity units as the area units needed to achieve the biodiversity gain condition. Although it is a last resort option in the planning system, referring to excess units on a gain site via a BNG register, land agent or established land managers for offsite gains is an effective backup plan.

Producing the Plan and Report

All further information regarding new developments, the proposed development work, planned land use, recorded biodiversity metric calculations, important habitats present, different types of habitat on the site, any use of good practice principles and the completed metric work for pre and post-development value will feature across the biodiversity gain plan and report.

Each document plays a part in accomplishing the BNG policy on behalf of a client and assisting the decision-making progress from the perspective of the local planning authority when it comes to seeing planning permission granted. It also adheres to the restrictions of guidelines of any other decision-makers a developer would need to consider, such as CIEEM, DEFRA, Natural England, local nature recovery strategies (LNRS) and any issues affecting current or future development projects.

For more information on a biodiversity net gain report and plan, check out the brief explanation below:

BNG Plans

A biodiversity net gain plan will explain how to improve biodiversity compared between before and after the development and suggest biodiversity enhancements that will achieve a 10% net gain. Following the current and future biodiversity value readings, every step for securing the 10% gain of new biodiversity will be clearly laid out, simplifying the planning officer’s decision-making process.

BNG Reports

A biodiversity net gain report will focus on the biodiversity outcomes of the inspection. As with an ecology report the first time an assessment is conducted, all data sets from the inspection will be included in the BNG report, along with any other details that will help the planning officer as part of their planning decisions for granting or denying a planning condition.

Monitoring and Reporting

In tandem with producing a report and plan with the intention of passing it on to the local planning authority to determine that biodiversity net gain requirements have been met and simplify the planning application process, the ecological consultant may need to fulfil other requirements.

For instance, other cases could see the site suffering issues with air quality or climate regulations, a monitoring plan could be in place to keep tabs on the site’s biodiversity condition, or further guidance could be needed for utility providers, a responsible body or anyone else playing an important role in the developer’s approach to development, namely in a self-build.

Management and Maintenance

Sharing similarities to the possibility of monitoring a site, it may be necessary to provide ongoing management if any issues continue to be a problem in the future. Ideally, the biodiversity gain objective and related planning policies will be met with ease, but each site must be treated differently based on the circumstances, the local policy and the habitat type.

Past case studies can indicate how to deal with continuing problems. Likewise, a different approach will be used for any other case that applies to mandatory BNG, such as the small sites metric for understanding BNG on a small site from April 2024 onwards, habitats with long-term needs or dealing with any number of variables.

Such factors include a conservation covenant, a custom-build development, a minerals development, a phased development schedule, local development orders, nationally significant infrastructure projects, protected sites, simplified planning zones, smaller developments and much more.

Results from BNG Surveys

From the perspective of both the developer and the local planning authorities, a biodiversity gain plan will simplify planning decisions and fulfil the legal agreement that affects ecological connectivity, climate regulation, existing protections, reserved matters, irreplaceable habitats within a development site and other policy requirements.

Under the guidance of our expert team in our biodiversity net gain consultancy, the information submitted as part of a BNG plan will also play an important part in the planning application stage. Measuring biodiversity and ensuring the mandate can be met is applicable in a significant number of planning applications, from a private development to a professional one and from a residential development to a commercial one.

Whether you’ve been able to achieve the mandatory condition with ease in the first place, different metrics were needed based on the planning conditions of your site, other habitats on the site altered your landscaping plans or you’ve been forced to purchase offsite biodiversity credits, the proposed approach will be an integral part of your development plans, contributing to granted planning permission.

Talk to Our Team About Achieving the Mandate

As you will have realised from the stages above, a lot goes into accomplishing biodiversity net gain (BNG), adequately satisfying the requirements of the local planning authority, and providing enough further information to outline planning permissions and see them granted. Even though previous versions of BNG offered much less flexibility, achieving sufficient statutory biodiversity credit requires assistance.

Any wide range of ecological features in your development may increase or decrease biodiversity value, and only by referring to a trained, qualified and licenced ecological consultant to establish a site’s pre-development and post-development value using the biodiversity metric can you understand what steps you need to take. From there, you can deal with protected species accordingly, succeed in reaching the increase to biodiversity quality or purchase statutory biodiversity credits, and satisfy other policies relating to planning and the environment along the way.

Select a relevant date approved prior to your development plans for our team to attend your site and allow us to undertake a biodiversity net gain assessment and support your efforts with expert advice. To get the ball rolling, speak to our team either via email, over the phone or by completing a quote form on our website. We will then take down your details and provide you with an accurate quote for a biodiversity net gain assessment and plan on your site.