Biodiversity Net Gain is “an approach to development that leaves biodiversity in a better state than before.”(1).  When applying biodiversity net gain principles, developers are encouraged to bring forward schemes that provide an overall increase in natural habitat and ecological features.  The aim of Biodiversity Net Gain is to minimise losses of biodiversity and help to restore ecological networks.

Biodiversity Net Gain is already part of the National Planning Policy Framework (NPPF, Para 170(d) and Para 175(d)) but the NPPF does not specify a number/percentage for the gain.  The latest update to the forthcoming Environment Bill includes a requirement for all future schemes including the development of land to deliver a mandatory 10 % biodiversity net gain.  This net gain will be required to be maintained for a period of at least 30 years.

Current thoughts are that meeting this ‘gain’ by off-site provision should be a last resort but there is much discussion to be had here.  Whilst some consider that off-site compensation could be seen as a ‘licence to trash’, others highlight the difficulties that achieving 10% gain will present to some sites.


Is a 10 % biodiversity net gain currently required?

The Environment Bill is effectively currently ‘in draft’ and although there are signs that this legislation will gain Royal Assent sooner rather than later, there is still some way to go and many details to be agreed before the Environment Bill becomes an Act of Parliament.

Furthermore, although a Bill may become an Act by way of Royal Assent on a particular day, this does not mean that the provisions of that Act will be immediately enacted.  Biodiversity Net Gain requirements are currently expected to come into effect during a two-year transition period which begins when the Environment Bill receives Royal Assent.

So is the requirement for 10% net gain in forthcoming Environment Bill currently a material consideration?

If the Act (and relevant provisions) are expected to become law within the timeframe in which a planning decision is being negotiated, then it would be wise to assume that the decision may be made in the context of that provision becoming law.  There is currently a 6 week period within which planning consents are open to challenge by Judicial Review.  In general terms, however, consents that are lawful at the time of the decision cannot be revisited should legislation change following grant of consent.

What this means is that the Environment Bill could be a material consideration but until it is very certain, it would be likely to be given little or no weight.  In the interim, other material considerations, including the requirement for net gain as set out in the NPPF, will apply.

At present, any requirements for percentage figures for gain, unless specified by local Development Plan Documents, will be set by negotiation with the Local Planning Authority.  Although many planning authorities are uncertain about what they can and should be asking for in terms of percentage gain, we at The Landmark Practice are finding that requirements for gain calculations are being made more regularly within pre-application advice.


Demonstrating net gain

Standard ecology reporting to inform planning applications (Ecological Impact Assessments) should include consideration of biodiversity losses and gains, but it is not standard practice to calculate a numerical value.

If you are asked to demonstrate a percentage (%) increase, your ecologist will need to run a metric/calculation.  This will be informed by measurements of pre-development habitats and application of criteria such as habitat quality and will result in a pre-development ‘score’.  The ecologist will then identify any losses of habitats or new habitats that will be created as part of the development, and apply multipliers to account for certainty of and timescales for establishment which will result in a post development score.

DEFRA has developed its own Biodiversity Metric (currently version 2.0) but other local tools are occasionally available and indeed may be required to be applied by local policy.  It is currently unknown whether the Environment Bill will require the use of the DEFRA metric in favour of others.


Net gain key messages

  • Biodiversity net gain is already required by the NPPF but this does not currently quantify the required increase.
  • There is an increasing emphasis on delivering biodiversity enhancement as part of development.
  • Biodiversity net gain requirements for development schemes should currently be informed by the local development plan and ideally via pre-application discussions with the LPA.
  • Longer-term projects with a more lengthy route to planning determination (e.g. such as site promotion) would be well advised to start to consider opportunities to deliver a 10 % net gain requirement which could come in to force before applications are determined.


Related Policy and legislation

Agriculture Bill:  On the 15th January 2020 the Government published its second iteration of the Agriculture Bill which is expected to become law in the summer of 2020.  The Bill proposes new agri-environment funding which will pay farmers for environmental services and benefits.  There is potential here to integrate with biodiversity net gain requirements, allowing farmers to generate income via biodiversity conservation.  The Environmental Land Management scheme (ELMs) is currently being trialled and development of a single system of biodiversity assessment and recording that responds to the requirements of both draft Bills will clearly be helpful.

The 25 Year Environment Plan (2018): sets out a commitment by the Government to leave the environment in a better state than inherited.  Whilst the biodiversity net gain concept is currently being developed as part of the Environment Bill, the 25 Year Environment Plan also includes proposals for a broader ‘Environmental Net Gain’ requirement which would consider wider ecosystem services (e.g. water availability, carbon storage, flood risk).