How to get started with BNG compliance

There’s not long left until developers spearheading public sector construction projects will need to ensure a minimum mandatory gain of 10% Biodiversity Net Gain (BNG) value. Research shows there has been a 13% decline in the average abundance of wildlife in the UK since the 1970s and few would disagree that we will not reverse this trend unless we take some action now. 

Defra has confirmed the November 2023 deadline for compliance remains, with the exception of smaller sites which now have an extra 12 months (November 2024) to prepare and get their processes and procedures in place to meet the legislation. BNG needs to be considered from planning and design right up to the 30-year guarantee management of the biodiversity at the site.

The government will permit, in some cases, the delivery of net gain through improvements away from the site, but developers will need to purchase credits. To date the details of this scheme have not been disclosed. 

In the meantime, there is much that can be done in the here and now and our a six- point checklist is designed to support construction industry professionals, with each point linked to the word NATURE. 

Numbers 

Let’s start with the numbers and the 10% Biodiversity Net Gain value requirement. It is effectively establishing a metric by which the impact needs to be assessed, monitored and reported and will be a mandatory minimum. 

However, when assessing any development, you also need to factor in the remediation, which means any biodiversity measures needed to get the development to a zero footing, from which is it possible to then add the 10% gain. For example, if a development is planned to reduce a site’s value in Biodiversity Units by 40%, then the development needs to plan a 40% remediation before planning the additional 10% uplift.  

Consider how much BNG is going to cost as a percentage of the overall build cost and the current land value. The DEFRA calculator tool can help you to get a figure, by supporting you in assessing the biodiversity unit value of an area of land and measure and account for direct impacts on biodiversity. 

You can also compare proposals for a site – such as creating or enhancing habitat on-site or off-site. Brownfield sites are often easiest to develop from as they tend to have lower existing pre-development value in terms of Biodiversity Units.  Offsetting will play a key role for those developments where it is difficult to achieve remediation, plus the additional benefit. 

Assessment 

A Biodiversity Net Gain assessment report will be the output delivered to a client by an ecologist who has been instructed to undertake an assessment. Each may have varied content, but essentially, they will include a biodiversity baseline including a habitat and trees survey. 

There will also be a quantitative biodiversity calculation and an assessment on post-intervention biodiversity – habitats lost, retained and enhanced.  They should also include upfront the methodology they’ve used, including local planning policy and national planning policy frameworks. 

Team 

One of the key ways to get ahead of the BNG requirements is to make sure you have the right skills and team on hand to support. At the centre is the client team who have overall responsibility for evidencing the BNG as part of the planning process. But there are other people involved too. Architects and landscape design will support the client team in the remediation and enhancement opportunities. The ecologist is responsible for completing the metric and providing input to landscape design that will influence biodiversity. Landscape management will provide the on-site maintenance and management needed to keep within the biodiversity plans and planning consent. 

Understanding 

It goes without saying that getting a handle on meeting mandatory BNG targets needs to include a commitment to gain a full understanding of what’s expected as part of a build. This article is a start at guiding you in the right direction, but there are lots of other resources to tap into. Read the full government report so you have a clear picture of what is or isn’t expected. SCF has a BNG tool which can guide you and has a full page of resources to help you to build knowledge further. It is important to get some knowledge yourself before bringing in the experts – you can potentially save time and money if you know exactly what you are asking for from the start. Once you have this knowledge you are better placed to determine clear and measurable goals to work with. 

Review 

In addition to the enhancements to be designed into a project to increase diversity, there are requirements for a 30-year management plan for delivered nature enhancements guaranteeing longevity. It’s important that decision making on the 30-year plan is built in at the earliest stages of designing a project, so that this requirement can be met over the long-term.  Your assessment report should include guidance by the ecologist on management plans ongoing and a suggested compliant monitoring regime. 

Evidence 

The government will permit some delivery of net gain through off-site improvements. As mentioned earlier, a credit scheme is in development, but Defra has said that this should be ‘a last resort’. Money raised through the credit scheme will be re-invested in habitat creation schemes. Offsetting will play a role in delivering Biodiversity Net Gain for those developments where it is difficult to achieve remediation. It will be a carefully managed process and will require due consideration, with safeguards and certainty.

Different habitats are prioritised as being rarer and more valuable. It is worth understanding the conservation intent of the area surrounding the development so that offsets can be targeted at valuable habitat enhancement. Bear in mind that some habitats are more difficult to nurture and deliver than others.

Kingsley Clarke and Adam Sanford are operations leads at Southern Construction Framework