Biodiversity Net Gain gathers momentum: implications of policy changes, the Defra metric and consultation response

Biodiversity Net Gain gathers momentum: implications of policy changes, the Defra metric and consultation response

Recent months have seen a change in momentum in terms of biodiversity net gain, with the various components needed to drive the process: the policy; the Defra Metric, and some of the detail of how the process will work all taking significant steps forward.

This article provides an overview of the evolution of the process to date, explores the emerging implications of policy, and reflects on the change in dynamic between planning authorities and developers that is likely to occur now that biodiversity net gain is a policy requirement in England.

What is biodiversity net gain?

In recent years with publications such as the State of Nature Reports[1] there has been a growing realization in Government and society at large that just protecting remaining areas with high biodiversity value (statutory and non-statutory designated sites) is not sufficient to halt the significant decline in biodiversity in the UK. Positive action is required to restore our biological resources (habitats and species) to a point that will enable them to be sustained for future generations. To help achieve this aim, the Government in England has identified a need for all development to deliver a Net Gain for biodiversity in the National Planning Policy Framework (NPPF) and accompanying National Planning Policy Guidance (NPPG). The simple Government definition of development-related Net Gain is; development that leaves biodiversity in a better state than it was before development.

A key element of the net gain policy is that changes should be measurable. As a result we have seen the development of Biodiversity Net Gain Metrics or Impact Assessment Calculators that allow losses and gains in biodiversity to be measured in an objective and repeatable manner.

What is the current situation with biodiversity net gain?

The term Biodiversity Net Gain first appeared in 2012 when Defra launched trials of how a biodiversity metric might work. Since then various metrics have been developed and revised, all of which are based on the trials.

In July 2019 Defra and Natural England published the results of the biodiversity net gain consultation. The long awaited new Defra biodiversity metric 2.0 was also issued, along with helpful guidance for developers and the ecology profession on how to apply it. It is expected that the new Defra metric will be seen as the new ‘national standard[2].’

Updated and revised National Planning Policy Guidance (NPPG) for England has also been released. This sets out how Government thinks policy should be implemented in the planning system. The key changes are the increased prominence given to biodiversity net gain and the language used to give certainty to those using the planning system that biodiversity net gain is here to stay. The number of references to biodiversity net gain has increased from three in the previous NPPG to thirty in the latest version. Statements in the NPPG such as ‘strategic policies can be used’ and ‘the National Planning Policy Framework (NPPF) encourages net gains for biodiversity to be sought through planning policies and decisions’ will give comfort and confidence to local planning authorities that they are right to be asking developers what measurable biodiversity net gain their applications propose and how they will deliver it, regardless of whether the authority currently has a live biodiversity net gain policy.

What are the key points from Defra’s Net Gain consultation response paper?

  • Exemptions – There will be no new broad exemptions for developments beyond those that already exist[3], with the possible exception of permitted development and householder applications (such as domestic extensions). Targeted exemption may also be introduced for brownfield sites meeting certain criteria e.g. those that do not support priority habitat types. Government also intends to introduce a simplified process for minor developments (less than 10 dwellings) so as to avoid ‘additional new survey requirements.’ It is not yet certain how this will work in practice.
  • 10% Net Gain – The forthcoming legislation will require development to achieve a 10% biodiversity net gain.
  • Existing legal and policy protections for protected species and sites will remain in place, and irreplaceable habitats, such as ancient woodland, ancient and veteran trees, blanket bog and limestone pavement, will not be included within the biodiversity net gain requirement. The Government is still considering how to approach net gain requirements where development affects statutory site designations.
  • Local Wildlife Sites (LWS) will continue to be afforded protection through planning policy requirements set at the local planning authority level. No additional net gain increase beyond the 10% will be required for habitats within LWS designations affected by development.
  • Delivering biodiversity outcomes – Government will require net gain outcomes to be maintained for a minimum of 30 years. A public register of habitat improvement sites will be created to provide clarity on where, how much and what type of habitat is being created and which development it relates to.
  • On-site vs off-site compensation – Government is not specific as to how net gain will be achieved. There is currently a general presumption that net gain measures should be delivered as close as possible to where biodiversity is lost, but this is not always going to be possible or even desirable if net gain further afield delivers additional benefits such as expanding or linking important areas of wildlife.
  • Tariff – The tariff rate for the cost of statutory biodiversity units will be based on that set out in the Defra net gain consultation document i.e. between £9,000 and £15,000 per biodiversity unit.
  • Local Planning Authorities – Government will assess the requirements and provide additional funding to local planning authorities to help them get ready for biodiversity net gain.
  • Environmental net gain policy requirements are on the radar of Government and there is reference made to the eco-metric currently under development between Natural England and the University of Oxford.

What is a Biodiversity Metric and which metric should be used?

A Biodiversity Metric ‘provides a way to measure biodiversity loss and gain in a consistent and robust way’. It essentially generates a biodiversity value measured in biodiversity units for a site before development commences and after development is completed, allowing the difference (positive or negative) to be measured. The calculation is based on habitats only, and for each habitat or habitat parcel, a biodiversity value is generated based on three factors that are multiplied together. These are:

  • the area of the habitat
  • the value (or distinctiveness) of the habitat
  • the condition (poor, moderate or good) of the habitat.

Where habitat creation or enhancement is proposed to compensate for loss of biodiversity value multipliers are used to reflect the time it will take (i.e. 5, 10, 15 years) for the required condition of the target habitat to be achieved and the difficulty of creating the target habitat in the first place. Whilst these are called multipliers, the effect they have on the number of biodiversity units that proposed new or enhanced habitats will deliver is to reduce them. This reflects uncertainties around the effectiveness of habitat creation and enhancement.

Biodiversity metrics will be the bedrock of any Net Gain assessment and as such understanding how they work and the pros and cons of retaining, enhancing or creating habitat will be essential to helping maximize biodiversity net gain and minimizing biodiversity loss in development design.

In the absence to date of a national standard, many developers have been using the Warwickshire, Coventry and Solihull Biodiversity Impact Assessment (BIA) metric, the most advanced, tried and tested metric available. There will be a cross-over period, as developers move to the new Defra Biodiversity Metric 2.0 which will become the industry standard. Hopefully, there will be a pragmatic approach adopted by local planning authority areas for developers who have to date voluntarily used the Warwickshire metric, to avoid repeating metric associated work or leading to unnecessary costs.

Changing dynamics

Now that the planning process provides certainty that biodiversity net gain is a requirement, there is likely to be a change in dynamic in the relationship between developer and authorities. Developers are likely to start asking for assurances about where, when and how their money is to be spent so that they can be confident that it will not be unduly held in local government budgets. The ability to find land to deliver the biodiversity net gain will also come into increased focus, particularly where schemes are not developer-led.

How we can help

BSG Ecology understands how to deliver projects that meet biodiversity net gain policy requirements. We are already working with our clients to use the new metric to assess landholding potential to deliver biodiversity net gain and to take individual developments through the planning application process.  Please contact one of our offices if you would like pragmatic help and advice


[1] State of Nature reports 2013-2019 State of Nature Partnership

[2] The British Standards Institute is currently preparing a new standard that will provide guidance on what ‘good measurable biodiversity net gain’ looks like. This will complement the metric and build on policy.

[3] For nationally significant infrastructure and marine development.

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