Image: man with hat opening notebook in forest.
Biodiversity Net Gain Assessment Reporting
Biodiversity net gain (BNG) became a legal requirement in the planning process for the first time in February 2024. It’s a long-term protective and enhancement measure for the natural environment that derives from the Environment Act 2021.
Achieving BNG now requires would-be developers to prove to local planning authorities that, over the next 30 years, their development site will somehow exist in a state where “the quantity and quality of biodiversity is measurably better” than it was pre-development.
It is anticipated that BNG will be a constant feature of planning in the future. Because of this, the onus is on developers to ensure they understand the concept—along with all the pertinent factors that compose it—inside and out. One of the most significant components is that, without a BNG report, the local authority won’t give planning permission. In this article, we help any potentially lost developers navigate BNG reports.
Differences between BNG Report and BNG Plan
There are at least two kinds of documents involved. A report and a plan are similar in that they accomplish the same goal and generally appear together, but in reality, they serve two distinct purposes: one supporting the planning application to the local authority, and the other supporting the actual development.
A biodiversity net-gain report would present the survey findings, such as the ecological features found on the development site, the metric readings necessary to establish anything of significance, and any other noteworthy data that could influence decision-makers.
A biodiversity net-gain plan, on the other hand, would elucidate the steps necessary to ensure the site achieves net gain, which in this case would mean a 10% uplift in the biodiversity standard necessary for the site.
Both of these documents are vital to the planning process and paired together often.
Image: green silos in a field next to a pond.
Core Features of the Biodiversity Net Gain Report
A biodiversity net gain report possesses multiple essential and globally recognized elements that provide local authorities with the necessary information to smooth the path for planning decisions. The report gives developers the assured clarity they need to meaningfully shape the direction of their development plans. This clarity informs a well-established statutory development process, allowing for a range of pre- and post-planning decisions. We will look more closely at the components of a BNG report in the next section.
Baseline Assessment
An ecological consultant can determine the current biodiversity worth of the habitats within the red-line boundary of a development site by doing two main things.
First, they study what’s known about existing habitats in the area from desktop.
Second, they physically inspect the development site and all its animal and plant inhabitants.
Because BNG assessments demand such close attention to detail, each element of a site that an ecological consultant determines is either present or absent has a unitary value that accurately reflects the state of the development site.
When all the readings are finally added up, they yield a figure. The development control figure will be the pre-development figure that contains all the ecological and biological community attributes of affected areas and provides a deep understanding of the site and its wave of biodiversity as required for the project to go ahead.
Assessing Impact
To compare the natural environment’s condition before and after development, an ecologist must create a biodiversity value that reflects the predicted state of the site.
This means the BNG consultant must do some work. Between reviewing all development plans and having detailed conversations with the developer and other project stakeholders, the BNG consultant must read all the project outcomes related to biodiversity. Outcomes that, with a little critical thinking, might be used to tell a story about the project’s impact on biodiversity.
All factors will be worked into the post-development figure, including any habitat loss caused by the removal of natural features or any habitat gain from operating with a sustainable or green approach. Using pre-development and post-development figures makes it possible to convert current and future assets all over the site into numerical data sets. Both numbers can then be analysed and compared to secure the 10% gain and meet the BNG objective.
Biodiversity Metric Calculations
The Biodiversity Net Gain (BNG) concept was first presented in 2019. Since then, it has been the Department for the Environment, Food and Rural Affairs (DEFRA) that has most obligingly and effectively taken the lead and the initiative in providing the biodiversity metrics that the planning profession and consultants require in order to apply the BNG concept to their daylighting ecological work, as necessitated by new planning legislation. The statutory biodiversity net gain metric that DEFRA provides has undergone several updates, at least partly in response to feedback from professional ecologists and their consultations.
DEFRA has also given the option to create different metrics, such as a small sites metric released in April 2024, to achieve biodiversity net gain on any developments involving a small site. That said, all these different metrics will be used in the same way, which is to establish pre-development and post-development values of biodiversity and then compare the two to establish any deficit, which will then be navigated in some way to secure the 10% requirement.
Image: computer showing green pop-ups.
Mitigation and Compensation Options
Biodiversity calculations provide the ecological consultant with critical information. From here, the consultant will decide on the optimum methods to create new habitats. The aim is to counteract any negative impact on the site, and above all, to enhance biodiversity.
A hierarchy in the biodiversity gain system will feature prominently in this decision-making and in the justifications that accompany it. The highest priority outcome in the hierarchy is avoiding “impacting ecological features.” If this is not possible, then the next best outcomes are “minimising damage,” “restoring other features,” and “offsetting to elsewhere.”
Meeting the legal requirements avoids harming rare and valuable ecological assets. If habitat loss is minimal, we can skip unnecessary steps such as creating new habitats, planting more trees and shrubs, or exercising any other ecological restoration components that might be found in a standard environmental plan. In its impact assessment, the project will rely on the site-specific data collected during its baseline assessment. Depending on how the data pans out, the chosen mitigation measures will vary.
Off-Site Gains
A consultant for biodiversity net gain will always do whatever is necessary to see the legal agreement achieved and set in motion on-site. However, that is not always possible. If it isn’t, they are left with the last resort of investing in (off-site) biodiversity measures. The number of biodiversity units needed to deliver BNG, of course, has already been confirmed over the previous steps. So the developer would only need to secure biodiversity units or credits to the same effect—that is, to the same value that would deliver BNG were it set up and running on-site.
Following many alterations to the system, biodiversity offsetting is currently done under a clear structure. There is now a register, known as the BNG register, for indexing all suitable offsetting sites, and a land agent can be called upon to ensure that the offsetting is done properly. The register and its land agents help ensure that off-site biodiversity unit purchases are used to target specific land uses and make otherwise unavailable offsetting habitats available for that purpose.
Why You Need a BNG Report
Given that local authorities are now insisting on proof of compliance with the BNG policy, there is little doubt that a biodiversity net gain report has become an absolute prerequisite for making certain that we are indeed making gains.
Only a BNG report can ascertain the present and future condition of the site in respect of biodiversity and the kind of information provided in the BNG report is going to significantly sway the decision-making of the planning officer, who can either grant or deny planning conditions.
Alongside the parameters set by the local planning authority, a biodiversity gain report has developers adhering to a range of other planning duties. These include local nature recovery strategies (LNRS), obligations relevant to nationally significant infrastructure projects, and what pertains to sites of special scientific interest (SSI) or any area with current protective measures, such as a conservation covenant. These diverse strands of policy aim for the same end: a recovery of nature.
Contact our Panel of Ecological Consultants
Before you can achieve biodiversity net gain on your development site, you must first have a Biodiversity Net Gain report prepared.
This report passes judgment on the site’s current and anticipated biodiversity worth. The value is judged in the context of the statutory biodiversity metric. The BNG report considers any proposed alterations to the site—be they on-site or off-site—that could reasonably be expected to affect the site’s biodiversity. It also looks at any proposed actions to the site that could honestly be described as “conservation.” In the end, good sense (and the law) requires that any site alterations resulting in “gains” also be substantial and measureable.
Biodiversity Surveyors are relied upon by clients for development projects of all kinds. Since the emergence of biodiversity net gain, we have kept ourselves up to date with the policy surrounding it, and now count it as part of our expert knowledge. If you wish to discuss any aspect of this with us, we can be contacted via the enquiry form.
