BNG stands as a testament to a dedication to our natural world and future generations, where development and nature conservation walk hand in hand. It's not just about creating new habitats but enhancing the ones already blessing our Earth, making places richer for wildlife and more vibrant for people.

The beauty of BNG lies in its measurement through the biodiversity metric, a tool turning changes in habitat quality and extent into quantifiable indicators of nature's health.

This commitment to nurturing biodiversity brings into play an updated biodiversity metric, beckoning developers, landowners, and local planning authorities (LPAs) to partake in an environmentally mindful journey. Integral to this journey is the careful assessment of the biodiversity present and the meticulous calculation of net gain using the new statutory biodiversity metric. It's a call to action for those shaping our environments to measure, evaluate, and enhance biodiversity meticulously, ensuring each development leaves the natural world richer.

As we delve deeper into understanding BNG and the pivotal role of the new metric, it's crucial for developers and all stakeholders to embrace this evolution in conservation efforts, setting a new standard in building a sustainable future.


What is The Statutory Biodiversity Metric?

hedgerow unit

The Statutory Biodiversity Metric, developed by the Department for Environment, Food and Rural Affairs (Defra), represents a significant advancement in the measurement and enhancement of biodiversity within development projects. Its creation stems from a need to standardise how BNG is calculated, ensuring a consistent and reliable approach across the board.

Here's a closer look at what this metric entails and its pivotal role in the BNG process:


What it Measures

The metric assesses biodiversity through three main units:

·       area habitat units

·       hedgerow units

·       watercourse units

It quantifies the ecological value of habitats before and after development, thereby calculating the net gain or loss of biodiversity due to the project.


Calculation Methodology

At its core, the metric uses a formula that considers various factors such as habitat size, condition, strategic significance, and type. This includes both existing habitats and those planned for enhancement or creation. The metric also incorporates risk multipliers and trading rules, which set minimum habitat creation and enhancement requirements.


Significance and Use

Designed for use by ecologists, developers, and local planning authorities, the metric ensures that developments achieve at least a 10% biodiversity net gain, in line with mandatory BNG requirements effective from February 2024 for most major developments.

This is achieved through a two-step process: first, meeting the trading rules to ensure no net loss and then aiming for the net gain. The metric facilitates the calculation of biodiversity units and provides a comprehensive guide on inputting relevant data values, making it an indispensable tool throughout all project stages.


Competency Requirements for Use

One of the core principles in utilising the Statutory Metric tool is that it must be completed by a "competent person."

Effectively, a competent person is a person who is skilled in performing and reviewing biodiversity metric calculations, acquired through training, qualifications, experience, or a combination of these elements. Competency has been aligned with the British Standard BS8683:2021.

The introduction of the Statutory Biodiversity Metric marks a crucial step forward in environmental conservation efforts, emphasising the importance of biodiversity in development projects. Its development and significance lie in its ability to provide a standardised, evidence-based method for quantifying habitat changes, ensuring that developments contribute positively to the natural world.

The Statutory Biodiversity Metric Explained

Tree inside biodiversity unit

Delving into the heart of the Statutory Biodiversity Metric, it's essential to grasp its foundation and its pivotal role in achieving BNG. At its core, the metric is underpinned by four key factors that ensure a comprehensive and accurate assessment of biodiversity values:

  • Habitat Size: The habitat area's scale directly influences the number of biodiversity units.

  • Condition: The current health and quality of the habitat affect its value for wildlife.

  • Distinctiveness: The rarity or uniqueness of the habitat, highlighting its importance in the ecosystem.

  • Strategic Significance: The habitat's contribution to local, regional, or national biodiversity objectives, emphasising its conservation priority.

These factors are meticulously calculated, reflecting the intricate balance of our ecosystems and the imperative to enhance them through development projects.

For developers, local planning authorities, and land managers, navigating the BNG process involves understanding and applying the metric effectively.

Key considerations include:


Compliance and Local Requirements

Local authorities oversee BNG compliance, potentially leading to delays due to varying interpretations and the need for additional training. Developers should stay informed about local stipulations extending beyond the metric or the standard 10% uplift, ensuring projects meet all regulatory requirements.


Development Viability and Creative Solutions

While BNG can impact the feasibility of development, especially for smaller projects, innovative approaches can meet BNG requirements and enhance the development's attractiveness and value.


Off-site BNG Units

In instances where on-site BNG is unachievable, developers may purchase off-site BNG units from a BNG Unit provider such as a Habitat Bank.


Statutory Biodiversity Credits

If no provision for the required off-site BNG Unit is available on the market, Statutory Biodiversity Credits can be purchased at higher prices and volumes than the private off-site BNG Unit market as an option of last resort.

Understanding the BNG calculation process is crucial for all parties involved. The biodiversity metric tool, available in both macro-enabled and macro-disabled versions, facilitates this by:

  1. Assessing Baseline Biodiversity - Determining the number of biodiversity units present before development.

  2. Evaluating Development Impact - Calculating potential biodiversity loss due to development.

  3.  Planning Enhancements - Identifying measures to replace lost biodiversity units and achieve the mandated 10% net gain.

This tool, integral for developers, land managers, and LPAs, ensures that every development project contributes positively to our natural world, aligning with BNG's overarching goal.


Step-by-Step Guide to Calculating BNG

Construction worker takes a survey.

Embarking on the journey to calculate BNG using the Statutory Biodiversity Metric involves several methodical steps. This guide serves as a beacon for developers, land managers, and local planning authorities, ensuring that your project complies with the legal requirements and contributes positively to our natural environment.

Let's navigate through these steps together.


Step 1: Define the Project Area and Baseline Biodiversity

  •  Area Assessment. Begin by delineating the project area. This involves mapping out the boundaries of the proposed development site.

  • Baseline Biodiversity Evaluation. Utilise the metric tool to assess the number of biodiversity units present before development. This requires specific information about existing habitats, including their types, sizes, conditions, and strategic significance.

Step 2: Assess the Impact of the Development or Project

Calculate the potential biodiversity loss due to the development. This involves evaluating how the proposed changes in land management or development will alter the habitat's biodiversity value.


Step 3: Determine the Biodiversity Enhancements

  • Identify measures for habitat retention, enhancement, and creation. This also includes watercourse interventions, categorised into retention, enhancement, and creation.

  • Optimise. Aim to achieve the best possible gains on-site before considering off-site gains or buying statutory credits. This ensures that the project maximises its positive impact on biodiversity.


Step 4: Calculate the Biodiversity Net Gain Using the Statutory Biodiversity Metric

  • Calculate the net gain using the statutory biodiversity metric calculation tool. This tool, accessible via Defra's website, enables developers to compute the biodiversity value after enhancements and compare it against the baseline to determine the net gain.

  •  Review and Adjust. If the 10% BNG target has yet to be achieved, consider revising the site design or exploring off-site gains to meet the requirements.

By meticulously following these steps, developers and stakeholders can ensure their projects comply with the legal BNG requirements and contribute significantly to the conservation and enhancement of biodiversity.

The journey towards achieving Biodiversity Net Gain is a testament to our collective responsibility towards nurturing our planet for future generations.


Common Challenges and Troubleshooting

An architect at a desk drafting plans with a pen and ruler

Navigating the complex terrain of BNG can present several challenges and uncertainties for developers, LPAs, and environmental organisations. Understanding these common hurdles and exploring potential solutions is crucial for ensuring the success and integrity of BNG initiatives.


Ethical and Operational Challenges

Concerns about environmental organisations potentially supporting development projects for financial gains have been raised, alongside the risk of developers' greenwashing' biodiversity plans to appear more environmentally friendly than they are in practice.

A notable lack of guidance on monitoring and enforcing on-site BNG outcomes has been identified, suggesting a need for clear communication on the consequences of non-compliance and ethical guidelines for organisations involved in on-site BNG projects.


Practical and Regulatory Concerns:

Uncertainty around the practicalities of integrating BNG with other environmental schemes and enforcement procedures and the delay in guidance on LPA responsibilities and resources further complicate the BNG landscape.

The absence of ecological expertise and adequate resources within LPAs, coupled with the increased burden placed on them due to BNG requirements, calls for solutions such as adequate funding, recruitment of ecologists, or consultation fees for outsourced expertise.


Market Dynamics and Site-Specific Issues:

The lack of regulation or government centralisation for the market for biodiversity units creates uncertainty about local market value and information sharing among landowners.

Specific sites may be limited due to space constraints or contamination risks, necessitating more ecology-heavy design and management plans. Moreover, habitat enhancement must be maintained for at least 30 years after development, which may not align with public expectations for landscape aesthetics.


Suggested Solutions

To address these challenges, continued timely and detailed government guidance, alongside clear guidelines on pricing and regulation of the market for biodiversity units, is essential.

Long-term commitment to monitoring and evaluation, with clear guidelines for LPA monitoring, can help ensure the success and integrity of BNG projects.

Educating the broader public on biodiversity matters and transforming landscape architecture to position biodiversity as a fundamental element rather than an optional add-on can help mitigate public perception issues and enhance habitats around built assets.

By tackling these challenges head-on with strategic solutions, stakeholders can navigate the complexities of BNG more effectively, ensuring that development projects contribute positively to biodiversity and the environment.



Earth ball on green grass field

By exploring the BNG calculation using the updated Statutory Biodiversity Metric, we have illuminated the pathways for developers, landowners, and local planning authorities to align development projects with the imperative of biodiversity enhancement.

This endeavour adheres to the new legislation and sets a standard in marrying ecological preservation with development, highlighting the significance of achieving at least a 10% biodiversity net gain and the solutions available for addressing any shortfall.

The journey towards a sustainable future wherein development and nature conservation coexist harmoniously requires collective action and adherence to the principles detailed in the article.

By understanding the importance of each step in the BNG calculation process and utilising the Statutory Biodiversity Metric Calculation Tool, stakeholders can ensure their projects contribute positively towards biodiversity enhancement.

For those needing to address any shortfall in their BNG calculations, resources like Legacy Habitat Banks offer a pathway to compliance, underscoring the practical steps towards realising biodiversity net gain in their projects.

As we move forward, let us commit to this responsible and forward-thinking approach in all future developments, ensuring a more prosperous, more vibrant world for future generations.