Our planet teems with life, from towering trees to buzzing bees, each playing a vital role in a complex web called biodiversity. This intricate tapestry weaves together the variety of species, genes, and ecosystems that sustain our planet's health and provide us with the countless resources we rely on to survive.

However, as humanity continues to grow and develop, so it leaves a greater footprint on our natural environment, consequently the delicate balance of nature is under constant threat.  Habitat destruction, climate change, and pollution are causing species to disappear at an alarming rate, disrupting the delicate balance of nature.

This is where Biodiversity Net Gain (BNG) enters the stage.  BNG is a standardised system developed by the Department for Environment, Food and Rural Affairs (DEFRA), which allows the quantitative and qualitative measurement of biodiversity before and after a development takes place.

How does it work?

BNG goes beyond mitigating damage; it aims to leave nature in a demonstrably better state than before the development commences.  

This is achieved through sensitive site design demonstrating the biodiversity gain hierarchy has been applied, coupled with the use of a metric calculator.

The calculator is based on the premise that all habitats have a pre-assigned value, which is measured in Biodiversity Units (BU). If a development has more BU post development than it did previously, then there is a ‘net gain’ in biodiversity.

The Legislative Landscape

The legislative landscape across the constituent parts of the UK is somewhat complex. While the goal remains unified, the paths each UK nation is taking differ, reflecting their unique landscapes and legislative systems.


On the 12 February 2024 BNG became mandatory in England.  This means all developments, (with some exemptions), must achieve 10% biodiversity gain post development.

Development must demonstrate how the ‘biodiversity gain hierarchy’ has been followed, which is as follows: 

1. on-site habitat enhancement followed by creation,

2. off-site gains and

3. purchase of credits as a last resort.

Small sites are exempt until 24 April 2024, and this includes small housing developments (less than 1ha or 9 homes). Works under permitted development and small householder projects, or projects with limited habitat on site are completely exempt.


Within NPF4, Scotland's planning blueprint, biodiversity safeguarding and enhancement is a constant theme throughout.  However, the Scottish Government has not yet mandated a specific figure and the approach to measuring BNG is still evolving but a new "biodiversity metric" is on the horizon. 

Currently, NatureScot is working on the development of a Scotland-specific metric which, when implemented, will change the current approach to quantifying biodiversity enhancement.

To confuse the current position even further, within the structure of NPF4, Local Plans developed by LPAs have room to interpret the policies differently.  In the absence of clearer legislation, individual LPAs are requiring different BNG parameters to be met and in the absence of clear national guidance we are seeing already seeing some LPA’s setting their own temporary rules.


In Wales BNG has been coined as Net Benefit for Biodiversity (NBB) and since late 2023, all developments must demonstrate NBB.  

There are currently no fixed measurements, however, all developments are required to evidence they have followed a ‘stepwise’ approach in site selection and design, akin to the mitigation hierarchy, in the form of a Green Infrastructure Statement. Which should contain a scheme of enhancements for biodiversity proportionate to the nature of the development proposed.

The Welsh Government are working with Natural Resources Wales to develop a common approach to measure NBB and it is expected that further guidance will be published.

Northern Ireland

Currently, there is no specific mandate from the devolved government in Northern Ireland for new developments to achieve a particular BNG after completion.  However, their strategic planning policy statement emphasizes that LPAs should aim to restore and prevent biodiversity loss. They must also consider any designated strategies for biodiversity conservation.

Navigating the path to BNG

There is no doubt that the legislative landscape across the UK appears confusing. There is no ‘one-hat-fits’ all and the situation, particularly in Scotland & Wales, is a fluid and evolving picture.

What is clear is that all administrations are committed to a framework which leaves biodiversity in a measurably better state post development and are pushing forward a standardised method by which this can be done.

BNG is still in its relative infancy and as such, there will be teething issues which will have to be overcome and this is where Atmos comes in.  Now more than ever the importance of involving suitably qualified ecologists in the project design, from the earliest opportunity cannot be understated.   

Having already been involved in successfully applying the BNG metric across the UK we are able to equip you with the knowledge and tools necessary to minimize risks, maximize BNG achievements, and ultimately contribute to a healthier environment, all while ensuring your project remains on track and within budget.

One final thought, BNG should not be viewed as merely yet more legislative constraints; it's about enabling sustainable development that leaves nature in better state than we found, so that future generations can thrive and grow. 

The more BNG we demonstrate the greater the chance of a successful consent!

To find out more about how Atmos Consulting can successfully support you in in enhancing the biodiversity of your development and smooth the passage to a successful  consent contact a member of the team today.