In the face of ongoing environmental challenges, such as habitat destruction and species decline, biodiversity net gain (BNG) has emerged as a critical strategy to restore and enhance the natural environment. BNG aims to ensure that the biodiversity of an area impacted by development surpasses its original state, creating a net positive outcome. Currently mandatory in England and Wales for larger projects, BNG requirements are also gaining traction globally, with other jurisdictions, including the European Union and the United States, moving towards similar regulations.

To achieve BNG, a comprehensive understanding of the existing biodiversity baseline and its potential improvements is crucial. Traditionally, this process has involved extensive ecological surveys, making it time-consuming and expensive. However, as the legal obligations surrounding BNG increase, the need for efficient solutions has become evident.

In this article, we explore the concept of BNG, discuss the challenges associated with its implementation, and highlight the benefits of adopting a digital solution to bring BNG considerations into the forefront of infrastructure development. We will give focus to the BNG framework in England, given its relative maturity of development; a standardised methodology for implementing BNG analysis is currently in its fourth iteration.

What is Biodiversity Net Gain?

Biodiversity net gain (BNG) is a strategy to develop land and contribute to the recovery of nature. It is a way of making sure the habitat for wildlife is in a better state than it was before development. Effectively it is a way to ensure that the biodiversity of the area of land or water impacted by a new development such as a transmission line is left in a better state than the baseline.

What are the current legal requirements surrounding BNG for developers?

BNG is currently mandatory in England and Wales for all larger projects and for all projects from November 2023. Current legislation sets a requirement to increase biodiversity by a minimum of 10% compared to the existing baseline. Other jurisdictions such as the European Union and United States are progressing towards BNG requirements over the next 12-36 months. 

How does BNG work in practice?

BNG is measured using what is called a 'Biodiversity Metric' calculator that was originally designed by Natural England. It uses changes in the extent and quality of habitats as a proxy for nature and compares the habitat found on a site before and after development. Four key factors underpin this comparison - habitat size, condition, distinctiveness and location. These factors are used to calculate the BNG baseline metric, which often interlinks with Environmental Impact Assessment (EIA) and planning processes.

In early stages of project development, infrastructure developers define route* options which tend to be at least several hundred metres in width. These routes capture areas that may be suitable for development of the infrastructure whilst providing flexibility for its final positioning, which often changes due to more detailed understanding and feedback as the development progresses. BNG is a key factor to consider when selecting routes because of its relation to impact on the local environment and high costs of mitigation measures.

What makes the current BNG methodology complex?

Using the current manual methods ecologists are sent out to explore every route analysed as the 'default' process. Ecologists will use a mix of satellite data and GIS layers but mostly field surveys to ascertain the biodiversity baseline of each route to establish what it is like 'pre construction'. As paying for ecologists to walk 5 x 10 km routes is time consuming and expensive, often assessing the biodiversity baseline is left until the end of the route optioneering process. This results in the BNG being carried out on the preferred alignment; there is usually minimal consideration of other potential routes.

Given the volume of new projects entering development, current manual methods are struggling to keep up. With BNG now being a legal requirement, digital solutions are becoming essential for the BNG practitioner’s toolkit.

What if there was another way? 

Optioneer has the functionality to automatically calculate baseline biodiversity units for hundreds of potential route options. The software combines industry-standard datasets, official calculation frameworks and cutting-edge AI to analyse and suggest routes that highlight biodiversity value from the outset.

“Using Optioneer for BNG could save hundreds of thousands of pounds and 3 to 6 months of development time per project. Better oversight of biodiversity impacts at earlier stages can reduce costs and time arising from mitigation of landscape impacts, compensatory planting, and restoration of high priority habitats.”

- Dave Costello, Environmental Specialist

How does the digital solution work?

Environmental, Ecological and Topographical information from sources such as the European Space Agency, Natural England, Environment Agency, Forestry Commision, RSPB and Ordnance Survey are combined to create a National baseline database of predicted habitat types.

The pre-impact biodiversity baseline units for each habitat type are calculated via the following equation originating from the Natural England Biodiversity Metric 4.0:

(Area X Distinctiveness X Condition) X Strategic Significance

The information provided by the biodiversity baseline can be used to assess multiple route options to allow for comparisons with respect to Biodiversity as well as key metrics at a much earlier stage than is normally possible.

In addition, the tool allows for biodiversity units with highest distinctiveness to be avoided when Optioneer generates potential route options. Our unique methodology can be configured so that areas with highest biodiversity are weighted appropriately against other factors and avoided where practicable.

How does this integrate with the existing Optioneer software use case for routing?

The ability to undertake biodiversity calculations in Optioneer is an additional metric we can turn on for our users in addition to the existing routing functionality. Optioneer is already capable of identifying the existing biodiversity baseline based on available data but does not advise how to improve on the baseline to meet the Net Gain requirements. We are currently roadmapping this additional functionality and hope to bring it online soon.

In summary, Optioneer includes BNG earlier in route development to unlock the following benefits for both infrastructure developers and the environments in which they work:

• Minimising impact on biodiversity while balancing with other routing pressures
• Improved route selection decisions in long term 
• Time saving without compromising quality
• More robust evidence towards eventual planning application and EIA

Curious to see how it works in practice? We’ve just launched a trial of Optioneer for BNG on a range of infrastructure projects such as transmission lines, underground cables, hydrogen pipelines and water pipelines. Have a look at our press release for more information and keep an eye out for initial results!