Latest BNG updates – What changed from BNG 4.0 to BNG Statutory Metric

Defra’s Statutory Biodiversity Metric: What’s changed in the latest version?

The UK’s Department for Environment, Food and Rural Affairs (Defra) released the long-awaited Statutory Biodiversity Metric calculation tool, version 4.0, last March. Since then, Defra has collected more feedback and amended features, updating the tool to a final Statutory Metric.

The following is an informal look at what’s changed. The Statutory Biodiversity Metric calculation tool has advanced a long way to clarify what is required and expected in a biodiversity net gain (BNG) application. The official Defra summary of the differences is still to come, but here’s what we’ve noted:

Key Changes in the Statutory Biodiversity Metric

The Defra BNG metric has evolved to provide greater clarity on the requirements for biodiversity net gain applications. Below are some of the most noteworthy updates and changes:  

1. Clearer Definition of Irreplaceable Habitats 

“Irreplacable habitats” have been clarified and defined, as well as how the metric will handle enhancement and creation scenario changes. New regulations now govern which habitats qualify as irreplaceable, streamlining the process for developers and planners. 

2. New Sheets for Unit Shortfall Calculation 

Two new sheets are now available to allow calculation of “unit shortfall” in the biodiversity metric calculation tool. Pre-populated by macros based on your input elsewhere in the tool, these sheets will help you to determine where on-site and off-site credits do not generate enough gains and statutory credits need to be purchased.

3.  Background Calculation Updates 

Minor changes can be found in the multipliers and other background calculations in the metric tool. Small wording changes have also been implemented in condition assessments and supporting footnotes to offer more precise instructions.

4. Enhanced Clarity on Habitat Management and Monitoring Plans (HMMP)

There is more clarity in reporting and plans needed to support your BNG application. This includes more detail on the habitat management and monitoring plan (HMMP) which is required for BNG applications reporting significant on-site gains.  The HMMP offers a detailed plan, which depicts how the land will be managed over the 30-year BNG requirement. To provide a framework for drafting HMMP requirement, Natural England has released a non-compulsory template.

Additional Improvements in the BNG Metric 4.0 

1. Guidance on Strategic Significance Multipliers 

Guidance has also been provided on how to apply strategic significance multipliers. Additionally, the new metric includes clearer guidance regarding datasets to refer to where there is no published local nature recovery strategy (LNRS).

2. Updates to the Small Site Metric (SSM) 

The Small Site Metric (SSM), that’s similar to the Statutory Biodiversity Metric, as well as guidelines for its use are now available. Both tools follow a similar Microsoft Excel-based format, helping streamline calculations across different project scales. 

3. New Rules for Habitat Recording 

New clarity is also provided on how to record a number of habitats, including subtidal and intertidal areas, and habitat mosaics. There are key changes to recording ditches in Floodplain Wetland Mosaics, and irreplaceable habitats. 

What’s Next for Defra’s Statutory Biodiversity Metric? 

The Defra BNG metric is designed to provide more precision and reliability in BNG applications, supporting planners and ecologists alike. With these improvements, developers can better assess biodiversity losses and gains, ensuring compliance with statutory requirements.

We’re staying up to date on future updates to the statutory biodiversity metric and broader BNG metrics. Check back regularly for the latest insights and news. Learn how AiDash Biodiversity Net Gain Management System™ (BNGAI™) can help with 10% BNG planning for urban projects. Start your first BNG project now!