The Biodiversity Net Gain (BNG) regulations that came into force in England in 2024 were billed as the biggest change to planning rules in decades. From a nature recovery perspective, they were also an exciting change, offering a new, credible means of funding. Six months on from BNG’s launch, and with the recent announcement of the Government to restore mandatory housing targets, (which will rise to 370k new homes per year), we argue that government, Local Planning Authorities, and developers alike should embrace BNG and aim above the current mandated 10% net gain. 

How does BNG work ?

BNG means that developers must now deliver a minimum of 10% biodiversity net-gain for new developments, or, in other words, a measurably positive impact (‘net gain’) on biodiversity, compared to what was there before development. This measurable impact is calculated through DEFRA’s Statutory Biodiversity Metric. 

The requirement of BNG is a huge step forward and can be achieved through the restoration or creation of habitats on the same site as the development or at other sites. As a very a last resort, developers can purchase statutory BNG credits from the Government. 

 The mitigation hierarchy is key to delivering effective BNG, it means that BNG should only be considered once the planning mitigation hierarchy (avoid, reduce, mitigate and compensate) has been fully and sequentially followed at both strategic and site base level.If done well, BNG should support both the protection of important nature sites and provide new funding to support nature's recovery.  

These regulations become mandatory in England for Town and Country Planning Act (1990) developments in February 2024. Soon afterwards, in April, BNG was extended to small sites too, and is due to come into effect for Nationally Significant Infrastructure Projects (NSIPs) from late 2025. 

You can find out more about how BNG works from our briefing document published earlier this year.  

Six months on and a ‘BNG industry’ has developed, offering consultancy services and ecological assessments, as well as off-site ‘Biodiversity Units’ for developers to meet their new requirements. The rush into the market has been tempered by news from elsewhere. In May the National Audit Office published a report  which argued that BNG  was launched before it was ready, with risks to the long-term effectiveness of the policy.  Whilst The Wildlife Trusts acknowledged many of the challenges presented in this report, we disagreed with the sentiment that BNG came too early –  given the urgency of the nature crisis BNG couldn’t and shouldn’t have been delayed further.  

Going steady

To date only a handful of sites have been registered on Natural England’s off-site BNG Register and given that the delivery of off-site units and habitat banks is one of the key mechanisms that could drive nature recovery through BNG, it looks, from the outside, like we are off to a slow start. 

The BNG register opened in February and holds details of all the sites that are ready to or are already delivering off-site BNG. To be on the register, a site must have agreed their Habitat Management and Monitoring Plan and have a legal agreement that secures the delivery of the habitats for a minimum of 30 years. It is unknown exactly why there are relatively few sites registered, given the comparatively high number of BNG providers in the marketplace, however it is, in part, likely due to the lengthy and complex process of securing legal agreements. Also, as well as being potentially slow, the legal processes are new to many key players in the BNG value chain. Whatever the cause, it is imperative that more high quality, off-site locations and habitat banks are registered to ensure that developers can deliver mitigation and gains as close to their developments impact as possible.  

At present, The Wildlife Trusts, own and manage a third of the sites on the register, to find out more about these sites please use the links below: 

Demand is another key factor influencing BNG activity (and the number of off-site locations). Early, anecdotal signs from the market, combined with studies of BNG delivered before February, conducted by the University of Oxford, suggest that the majority of BNG is being delivered on-site - with the findings from the University of Oxford study indicating that off-site delivery made up just  7.4% of the sampled developments¹. Whilst this might indicate the mitigation hierarchy is being followed (see our briefing document for more information); the concentration of on-site units is far greater than previously anticipated by DEFRA, so there are concerns that biodiversity is being squeezed into ever smaller spaces. In addition, on-site delivery is thought to have greater risks of non-compliance, as on-site habitats are not required to be registered and are also likely to face greater human pressures and conflicting land uses.  

Aim high for real biodiversity gain 

There are some concerns that the current BNG regulations, that require just 10% gain, may limit the ability for BNG to support the delivery of the Governments 30 by 30 objectives. For example, a study of pre-mandatory BNG found that despite an average 20.5% uplift in BNG units, across a sample set of developments, there was an overall loss of greenspace by over 30%² . 

At The Wildlife Trusts we have consistently advocated for strengthening the regulations and requiring more than 10% which, due to the uncertainties surrounding habitat creation, is low enough to be within a margin of error. Given the biodiversity crisis we face, we believe that it is vital that 10% gain is not viewed as the ceiling. To ensure BNG is effectively contributing to nature’s recovery and delivering true, additional gains, we would strongly encourage developers to go beyond the minimum planning requirements and aim for at least a 20% gain for nature, to ensure their development has a positive impact on wildlife. 

As well as new BNG regulation, we are now posed with renewed and ambitious building targets from the new Labour Government which will most certainly test the nascent BNG regulation and markets.  We have welcomed early  engagement with the new UK Government and their pledge to “provide any legal underpinning that may be needed to ensure that nature recovery and building works hand-in-hand." Though, upping the ambition of BNG and working rapidly to expand BNG to include NSIPs would demonstrate that these welcome words are put into action. 

A number of evaluations and studies into BNG are already underway, including two studies commissioned by Natural England, including an Evaluation Programme for Biodiversity Net Gain (BNG) being undertaken by Eunomia and a consultation exercise, led by RSK Wildling, exploring BNG Assurance. Alongside these, over the last five months The Green Finance Institute has led a cross sector working group, that a number of colleagues from across The Wildlife Trusts have engaged in, exploring the current barriers, challenges and potential solutions for BNG delivery which has cumulated in the recent publishing of a  Biodiversity Net Gain: A Road Map for Action.  

Look to the future

To summarise, despite a seemingly slow start, the introduction of a compliance based BNG market marks a truly positive step forward and we shouldn’t underestimate the role it has played in bringing nature-based solutions into conversation. However, we are yet to see a full picture of how effective BNG will be in delivering nature-positive outcomes, for both space and condition of habitats.  

At The Wildlife Trusts we are an enthusiastic supporters of the principles of BNG and believe passionately that development can be designed in a way that improves nature rather than destroys it. Through our local Wildlife Trusts and Wildlife Trust Consultancies, we are working across England to develop high-quality BNG,  and now have over 25 BNG delivery sites (active or in development) that have been designed to maximise benefit to nature and people in perpetuity. Find out more about our work or how you can work with The Wildlife Trusts.

Find out more

¹ The Society for Conservation Biology (wiley.com) (Rampling, zu Emerson et al. (2023).

² The Society for Conservation Biology (wiley.com) (zu Ermgassen et al., 2021).