Collington Winter Environmental

BNG Assessment – How we Reduced Offsetting Costs for a Developer

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Biodiversity net gain (BNG) refers to the process whereby a development project considers the environmental impact in terms of biodiversity. BNG is a Government response which aims to ensure that biodiversity is left in a better state than before the development was completed. This is done by avoiding biodiversity loss, retaining various habitat types, and protecting any assets of strategic significance. It also aims to secure measurable net gains for at least 30 years.

BNG has now become part of UK legislation through The Environment Act and The Environment Bill. This means that it will become a mandatory point for all upcoming projects in England. BNG is also being requested more frequently by local planning authorities to inform planning applications and national planning policy framework.

BNG consultants can help to ensure that developers meet the mandatory biodiversity net gain requirements so that a development project can obtain planning permission.

How our experts helped developers to reduce offsetting costs

BNG Assessment saved our client, a developer, approx. £530,000 in Biodiversity Offsetting costs.

Our team were approached for advice regarding two projects in Widnes by a large house developer. The projects both had existing BNG assessments produced by a previous ecologist, finding net losses on both schemes. In this case, purchasing offsetting Biodiversity Units would have cost the developer nearly £730,000.

Our Director, Olivia Collington, was asked to review the BNG Assessments as well as Landscaping Plans for both schemes to assess if any betterment could be made. Olivia was able to recommend alternative habitats and planting within both schemes, which gave a significant betterment to the biodiversity value of the post development schemes. Following BNG Principles, schemes should always seek to follow the mitigation hierarchy, retaining and enhancing what is possible and compensating for what is lost. 

Our team were able to reduce the number of Biodiversity Units required to achieve a net gain by over 20 Units, saving the developer nearly £530,000 in offsetting requirements.

Within BNG Assessments, efforts should always be made to maximise on site provision for habitats, as was the case in these schemes. Our biodiversity team have expertise in both BNG and Ecology. Therefore, they are uniquely placed to offer advice on suitable habitats to achieve the best BNG results possible for development schemes. 

What is a BNG assessment?

A Biodiversity Net Gain Assessment involves evaluating the ecological impact of a development or land management plan. It entails comparing the initial biodiversity value of a location with the biodiversity value after development to measure biodiversity and ensure a net increase in biodiversity.

This net gain will be measured using the Natural England recommended biodiversity metric 4.0 or the small sites metric calculator tool depending on the size of the development.

Our ecologists can provide a consultation on the biodiversity metric and which version of the biodiversity metric you will require. They will then utilise the data gathered from numerous surveys to calculate the biodiversity value of the site, both prior to and following the implementation of the development project.

If the biodiversity value after development is less than the initial value, the developer must implement measures to compensate for the biodiversity loss. These actions may include establishing new habitats, improving existing habitats, or providing financial restitution to a conservation organisation. Offsetting efforts can be carried out either on the development site itself or elsewhere.

What is biodiversity offsetting?

Biodiversity offsetting is a conservation strategy that seeks to counterbalance the biodiversity decline resulting from development projects. Its objective is to generate positive biodiversity outcomes by creating or rehabilitating new habitats, as well as improving existing ones, thereby counteracting the adverse effects of development.

Biodiversity offsetting is typically employed as a final measure once all alternative approaches to prevent or mitigate the impacts of development on biodiversity have been explored. It is also utilised when complete avoidance of development impacts is not feasible.

There are a number of different ways to carry out biodiversity offsetting. Some common methods include:

  • Creating new habitats, such as wetlands, forests, or grasslands.
  • Restoring degraded habitats, such as those that have been damaged by pollution or development.
  • Enhancing existing habitats, such as by providing additional food or shelter for wildlife.
  • Providing financial compensation to conservation organisations that are working to protect or restore biodiversity.

How can we assist?

Our BNG experts can ensure your development projects are conforming to the current and mandatory legislation coming into force at the end of 2023, saving you both time and money. We can carry out a BNG assessment for your project to identify any BNG related issues that could effect your planning application.

Please get in touch if you require a consultation on how our BNG experts and land managers can assist you to deliver net gains on your development.

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23 Bark Street East, 1st Floor, Bolton



01204 939 608


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