Biodiversity Net Gain (BNG) CPD Talks

Over the past two months, Exo Engineering have offered a series of CPD lunchtimes talks focussing on the topic of Biodiversity Net Gain (BNG) legislation.

Biodiversity Net Gain (BNG) legislation was introduced at the start of 2024, requiring almost all developments on land in England to achieve a measurable 10% gain in biodiversity.

Following the legislation becoming legally binding, Exo Engineering began to deliver a series of Continuous Professional Development (CPD) talks. These informal lunchtime talks aimed to provide clear information about which types of development will be impacted, an overview of key terms, and how BNG can be achieved.

Due to the complex nature of BNG considerations we delivered two talks. The first provided a more broad overview of the legislation, with the second explaining how the calculation tool ‘Metric 4.0’ can be used to determine whether BNG has been delivered.

To explain how Metric 4.0 works in practice, a hypothetical case study was examined where a degraded conventional sea wall needed to be replaced. Replacing a degraded conventional sea wall which features smooth, flat surfaces with a sea wall that incorporated Integrated Greening of Grey Infrastructure (IGGI), such as the solutions offered by Exo Engineering would allow for the mandatory 10% BNG to be achieved.

We have collated some of the questions that were asked following our CPD talks, the responses to these can be found below.

• Something which we need to consider is "operation and maintenance" of BNG interventions to ensure "green asset" life span.

Definitely. It is hoped that the biodiversity credit market will continue to expand and evolve, aiding the funding of various aspects of BNG enforcement such as monitoring to ensure successful delivery. It is hoped that through the continued research of bio-armouring will shed light on the benefits of using Integrated Greening of Grey Infrastructure (IGGI) in coastal applications and the potential for increased lifespans when compared to conventional approaches.

There is currently some uncertainty about the implications for projects where BNG is not achieved after the 30 years, with “acceptable failure” likely to be assigned if best efforts have been made to achieve BNG. Where insufficient/no efforts have been made, court action maty be taken or fines imposed.

• Do we need to design annual surveys to identify if in.... say 30 years’ time we have achieved the gain?

• "Biodiversity Net Gain plan". Is this something undertaken on a project-by-project basis. Is this held by the "developer" or "asset owner" e.g., housebuilders?

Biodiversity gain plans must be submitted by the developer on a project-by-project basis. A competent person must submit regular reports  regarding the progress towards achieving the BNG which has been outlined in the plan, and also identify necessary measures which should be taken to bring BNG back on track. DEFRA are currently looking to develop a draft template and expand digital capability for the purpose of standardising the reporting of BNG progress over the 30 years.

• Do you think these engineering solutions will eventually form the backbone for biodiversity credits?

We see the greatest opportunities for eco-engineering solutions to be used for the creation of new habitat, such as in the replacement of a conventional seawall with a seawall with Integrated Greening of Grey Infrastructure (IGGI) as detailed in the Metric 4.0 demonstration. Artificial hard structures with IGGI still offer a relatively low distinctiveness score, albeit higher than that of conventional hard engineered structures, so are unlikely to represent opportunities for biodiversity credit provision.

• Would it be fair to say that BNG in this context is only really achievable on site where an existing internal hard structure can be improved? Have you removed a rocky shore habitat and achieved BNG?

There are two factors to consider here within the metric tool: Biodiversity Units and Trading Rules. Under the trading rules a high distinctiveness habitat (rocky shore) cannot be replaced by a lower scoring habitat. This means that this area must be maintained or offset with the same habitat. However, this in itself would not satisfy net gain as it doesn’t address the required increase in biodiversity units. This is where IGGI could play a role, by creating habitats to bring up the post development biodiversity score as part of the wider project.

• In the example you gave did you input the intertidal habitat as retained and enhanced in the metric?

For the seawall example explained in Metric 4.0, all existing habitat (conventional seawall, degraded) was lost. This was subsequently replaced, which created new habitat of higher distinctiveness (Artificial hard structures with Integrated Greening of Grey Infrastructure (IGGI))

• How can Biodiversity Net Gain contribute to enhancing the resilience of ecosystems against the changing climate patterns?

• How are the benefits of BNG "realised"?

• How does the concept of Biodiversity Net Gain intersect with strategies to address and adapt to the impacts of climate change in development projects? 

Biodiversity Net Gain seeks to measurable increase biodiversity and improve its condition. Increasing biodiversity in the context of both species richness and abundance will be incredibly beneficial to mitigate the effects of a changing climate on ecosystems. Biologically diverse communities are more likely to contain species that increase ecosystem resilience as there is a higher chance of any one species present having traits that enable them to adapt to a changing environment. In this way, such species could buffer the system against the loss of other species.  The principals of BNG encourage the creation of higher distinctiveness habitats for this reason, with higher distinctiveness habitats typically supporting higher species richness and greater complexity. Additionally, BNG legislation will not supersede wider legislation regarding climate change but is hoped to compliment existing policies to support more resilient ecosystems.

Recordings of both CPD talks have been uploaded to our YouTube channel, which can be accessed by clicking here.

Exo Engineering have worked alongside our clients to ensure their projects achieve Biodiversity Net Gain. If you would like to learn more about how our Nature Inclusive Solutions can help your infrastructure project to achieve its BNG responsibilities, please don’t hesitate to get in touch.