Biodiversity Net Gain Planning for Homeowners and Developers | What you need to know to get started

Biodiversity refers to the variety of life on Earth, including all species of plants, animals, fungi, and microorganisms, as well as the ecosystems they form. Maintaining biodiversity is essential because it supports the natural systems that provide us with clean air, water, fertile soils, and climate regulation. It also makes ecosystems more resilient to changes, helping them recover from disturbances and sustain life.

Biodiversity Net Gain (BNG) is thus a strategic approach to managing land and natural resources in a way that enhances or restores natural ecosystems as part of new development plans. The goal of BNG is to ensure that development not only avoids harm to biodiversity but actively improves it, leaving nature in a better state than before. This is now a key requirement in planning and development policies in the UK.

As of February 2024, Biodiversity Net Gain planning is now a mandate for any new developments in the UK. This new regulation is universally applied from small scale home additions to large scale developments, with very few exceptions. The approach seeks to balance economic growth with environmental sustainability, ensuring that future developments contribute positively to the natural world.

The concept of Biodiversity Net Gain planning originated from global efforts to address the loss of biodiversity. It started gaining momentum in the 1990s as environmental organisations and conservationists began advocating for a more sustainable approach to development, recognising that traditional methods often led to the destruction of natural habitats.

In England, BNG is rooted in the statutory framework established by Schedule 7A of the Town and Country Planning Act 1990, revised by the Environment Act 2021. This framework is specifically referred to as "biodiversity net gain" in the Planning Practice Guidance, distinguishing it from other general biodiversity initiatives

BNG is relevant to various stakeholders:

Developers: Developers are required to meet BNG thresholds before obtaining planning permission.

Landowners and homeowners: Particularly in cases of large estates or custom-build projects, landowners may need to consider how BNG affects their property.

Local Planning Authorities (LPAs): Legally required to check planning applications for BNG compliance. LPAs are responsible for preventing biodiversity loss through new development projects.

The law applies broadly, though there are a few exemptions, such as for small-scale self-build projects or household applications. However, the majority of new developments must comply, meaning that everyone involved in the construction process needs to be aware of their BNG responsibilities.

Legislation requires that new developments achieve a minimum of a 10% increase in biodiversity value, sustained over 30 years, compared to the pre-development state. Developers will have to submit the following documents to get approval, a complete metric sheet, habitat plan, and a Biodiversity Gain Plan (BGP).

The Statutory Biodiversity Metric Sheet is a document that uses the biodiversity metric tool to assess and calculate the biodiversity value of a site before and after development. The metric sheet quantifies the ecological impact of a project by assigning numerical values to different habitats based on their distinctiveness, condition, and area. These values are then compared to assess whether the development achieves the required 10% biodiversity uplift over a 30-year period.

The biodiversity metric tool is used to calculate biodiversity value in three main areas:

Existing habitats: Evaluates the condition, size, and ecological importance of the site before development.
‍Habitat enhancement: Assesses proposed improvements to existing habitats as part of the project plan.
‍Habitat creation: Quantifies the value of any new habitats developed on the site.

The biodiversity metric tool calculates different types of biodiversity units, split into three modules:

Area habitat units: Represent the biodiversity value of land-based habitats, such as woodlands or grasslands.
‍Hedgerow units: Assess the biodiversity value of linear features like hedgerows, which are essential for wildlife connectivity.
‍Watercourse units: Measure the biodiversity value of rivers, streams, or other flowing water habitats.

A numerical value is to different habitats based on their ecological characteristics. These units quantify biodiversity by considering several key factors:

1. Habitat Area
The size of the habitat is one of the primary factors. Larger areas generally support more species and greater ecological diversity, so the habitat area in hectares is an essential component of the calculation.
2. Habitat Distinctiveness
This measures how unique or rare a habitat is. Different types of habitats are assigned distinctiveness scores, ranging from low (e.g., improved grassland) to high (e.g., ancient woodland). The rarer or more ecologically valuable the habitat, the higher its score.
3. Habitat Condition
This factor assesses the current state or health of the habitat, taking into account aspects like vegetation cover, species diversity, and ecological integrity. Habitat condition is graded from poor to good, with better-conditioned habitats earning higher scores. Baseline condition is always set to “moderate” for small sites. 
4. Strategic Significance
This factor considers whether the habitat is located in an area identified as a conservation priority, such as a local nature recovery strategy zone or other key ecological areas. If a habitat aligns with local or national conservation priorities, its biodiversity value increases.
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5. Connectivity and Proximity
Habitats that are better connected to existing ecological networks, such as hedgerows linking woodlands or rivers supporting wildlife movement, are given higher scores due to their enhanced ecological importance.
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6. Time to Target Condition and Difficulty of Enhancement/Creation
When habitats are newly created or enhanced, the time it will take for them to reach their target condition is factored in. The difficulty of establishing certain types of habitats, such as wetlands, also influences the score.
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The formula used for calculating biodiversity units is generally expressed as:Biodiversity Units=Habitat Area (ha)×Distinctiveness×Condition×Strategic Significance

This formula is applied separately for different habitat types (e.g., woodland, grassland, watercourse). The biodiversity metric tool adds these values together to produce an overall score that quantifies the total biodiversity value of the site.

This is a detailed map or layout that shows the types and conditions of habitats both before and after development. It visually represents how the land's biodiversity will be managed and enhanced throughout the project.

Baseline habitats: A map of the existing habitats on the site, including their current condition and biodiversity value.
‍Proposed changes: Plans for enhancing or creating new habitats as part of the development to achieve a 10% biodiversity uplift.

A BGP is a comprehensive strategy that explains how the 10% biodiversity uplift will be achieved. It outlines specific actions for habitat creation and enhancement, as well as the management and monitoring needed to sustain these gains over a 30-year period. This document also ensures compliance with BNG regulations, offering a long-term approach to preserving and enhancing biodiversity. 

Distinct from the Metric Sheet and Habitat Plan, it focuses on the overall strategy for achieving and maintaining biodiversity enhancements in a development project.

Developers can achieve BNG in one of three ways:

On-site improvements – Developers can enhance or create new habitats directly on the development site. This includes enhancing existing habitats (e.g., planting trees, creating biodiverse ponds) or building appropriate green infrastructure like green roofs.
‍Off-site biodiversity units – If on-site gains are not possible, developers can compensate by purchasing biodiversity units from a separate landowner or generating them on their own land. These units must be approved and registered with Natural England.
‍Statutory biodiversity credits – As a last resort, developers can purchase credits from the Secretary of State to meet BNG requirements when neither on-site nor off-site solutions are feasible.

For developers, BNG represents an additional planning consideration, requiring detailed metric calculations and sustainable design. It’s essential to incorporate BNG plans early to avoid project delays and ensure compliance with local councils.

Joe's Blooms helps you fully comply with England's Biodiversity Net Gain rules with our best-in-class digital tools and specialist support.
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What do you get?
Your biodiversity gain plan
A completed Small Site MetricOrdnance Survey-based pre- and post-development plansCreate your free account today. 
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