Biodiversity Net Gain FAQs

From November 2023, all developers will be legally required to increase the biodiversity of their development site by 10% (with exceptions for some types of development.) This is known as ‘Biodiversity Net Gain’.

If the Net Gain cannot be delivered on-site, there is an option for it to be delivered off-site, on a different piece of land. Cornwall has adopted the ‘Biodiversity Net Gain’ policy early, requiring major developments to include a 10% Biodiversity Net Gain from 2020.

See below for answers to your frequently asked questions.

About our expression of interest form and how we will use your information

What am I signing up for, and how are you using my information?

By providing us with some of your details, you are expressing an interest in delivering off-site Biodiversity Net Gain on your land.

Your data will only be shared with a few officers from Cornwall Council’s Nature Recovery team for the purposes of contacting you regarding this opportunity. Cornwall AONB, Cornwall Wildlife Trust will also be able to view these details, as partners involved in the delivery of the website Daras.

For more information about how we use your data, please have a look at the Daras Terms of Use.

About Biodiversity Net Gain

What is Biodiversity Net Gain?

‘Biodiversity Net Gain’ is a concept outlined in the Environment Act 2021, meaning that as of November 2023, all developments (with some exemptions) will be legally required to increase the biodiversity of the development site by 10%. Developers will have to submit information outlining how they will do so when they apply for planning permission.

Cornwall Council, as a Local Planning Authority, has adopted this policy early, requiring all major developments to achieve a 10% Net Gain since March 2020.

What is ‘biodiversity’?

The biodiversity of an area is the variety of plant and animal life within it. A high level of biodiversity is considered to be important – as wildlife supports health ecosystems that we rely on for clean air and water, flood resilience and climate stability.

We are currently experiencing unprecedented losses in biodiversity worldwide.

How long does Biodiversity Net Gain apply for?

The achieved Biodiversity Net Gain of a site will have to remain, legally, for 30 years.

What is the Environment Act 2021?

The Environment Act 2021 is a piece of environmental legislation that passed in November 2021. It includes legislation regarding specific environmental policy areas including waste, air quality, water, nature and biodiversity.

What is ‘off-site delivery’ of Biodiversity Net Gain?

If Biodiversity Net Gain cannot be delivered on-site, it is permissible for it to be delivered off-site, on another parcel of land. This is known as ‘off-site delivery’ of Biodiversity Net Gain. The land used for off-site delivery will have to show an increase in biodiversity, measured using a standardised metric.

In order to decide how Biodiversity Net Gain can be delivered, it must first be passed through a ‘mitigation hierarchy’ (see below). Avoidance of off-site delivery is prioritised.

1)      Avoidance Developments must take measures to avoid impacting the biodiversity levels of a parcel of land.
2)      Minimisation If impacts on biodiversity cannot be avoided, they must be minimised.
3)      Onsite Restoration Measures taken to rehabilitate the degraded habitat on site must be taken.
4)      Offsite Delivery If the above three options have been considered in full, and 10% Biodiversity Net Gain cannot be delivered on site, the remaining Net Gain units must be found from another site.

Working together

What is the financial return for me, if I deliver Biodiversity Net Gain on my land?

Delivering off-site Biodiversity Net Gain on your land will provide a guaranteed income stream. The value per acre will depend on the location and size of the land committed along with other factors including baseline habitat conditions.

Are there any costs for me?

At this stage, there are no costs for you to express interest in delivering off-site Biodiversity Net Gain.

Why is Cornwall Council involved in this process?

As a Local Planning Authority, Cornwall Council’s planning team are involved in the acceptance of planning applications and the consideration of whether they satisfy the Biodiversity Net Gain requirement.

Cornwall Council’s Nature Recovery team is interested in ensuring that off-site delivery of Biodiversity Net Gain is done in such a way that works (well for nature, and) for you.

Measurement and verification of Net Gain

How is Biodiversity Net Gain measured?

Biodiversity Net Gain is currently measured using the metric 3.1, created by Natural England. This metric is used by developers to measure the pre- development and post-development biodiversity value of habitats on a piece of land. These biodiversity value of these habitats is quantified into ‘biodiversity units’.

How do I use the metric?

As a landowner interested in delivering off-site Net Gain, you will have to use the metric to assess the amount of units on the land you are considering for delivery. You can find the metric and user guide here. As an off-site provider, you would only be required to use the off-site part of the metric.

To calculate the number of biodiversity units in an area, the following data is needed:

  • Habitat types
  • Area of each habitat parcel
  • Condition of each habitat parcel
  • Strategic significance of each habitat parcel

Biodiversity units can also be calculated from hedgerows, lines of trees and rivers/ streams.

I don’t feel qualified to use the metric/ I don’t have time to use the metric. Who can help me?

The person using the metric should be able to confidently identify positive and negative indicator species for the range of habitats likely to occur in a given geographic location at the time of year the survey is undertaken.

Can I overlap the land I want to use for Biodiversity Net Gain with other schemes, such as Countryside Stewardship agreements/ ELMs, or payment for other environment services?

Whilst formal regulations have not been published, the Government intends for landowners to combine payments for environmental services from the same parcel of land, providing they are paying for distinct outcomes that are clearly ‘additional’.

Delivery of Net Gain, Monitoring, and Enforcement

Who is responsible for delivering off-site Net Gain, and managing the land for it?

If you choose to use your land for the delivery of off-site Biodiversity Net Gain, you, or any person who you employ/commission, are responsible for delivering the works.

How will the delivery of Net Gain be monitored?

When Net Gain becomes mandatory nationally (from 2023), it will be monitored by Cornwall Council’s planning directorate.

Land and ownership

How do I know I will be paid? / How are Biodiversity Net Gain agreements secured legally?

As of November 2023, when Biodiversity Net Gain becomes mandatory nationally, off-site biodiversity gains will need to be secured through a conservation covenant or planning obligation.

What if I sell my land before the 30 years are up?/What if my tenancy agreement is less than 30 years?

If you sell your land/ your tenancy agreement ends before the 30 years are up, then the Net Gain obligation is passed onto the new owner (and tenant).

Can I sign up for Biodiversity Net Gain if I don’t own my land?

Speak to the landowner to discuss this.

Does off-site delivery of Biodiversity Net Gain have to be within a certain distance of the development?/ Does Biodiversity Net Gain have to be delivered in certain places?

The biodiversity metric 3.1 is built in a way that means that offsite Net Gain closer to the original site is preferable.

The Biodiversity Net Gain process in the future

When Biodiversity Net Gain becomes mandatory, nationally, in 2023, what changes?

As Biodiversity Net Gain has not been rolled out nationally, there is no mandatory process for its delivery at present.

In November 2023, when it is mandatory nation-wide, draft regulations set out a clearer process. Developers must have formally secured land for off-site delivery and registered this land on a centralised register before applying for planning permission.


Useful links and resources

Guidance and links to assist your project and engage with Cornwall’s environment and economic development.

Find out more