With the Government’s plans to ramp up housebuilding and utilise planning to pursue growth, much attention has been paid to the environmental impact of development, and particularly the decline of England’s biodiversity.
Biodiversity Net Gain (BNG) has been in the policy pipeline for years, and statutory BNG was introduced in early 2024 as a way to use planning gain to mitigate and offset the loss of biodiversity caused by development, preferably on the development site itself. It functions as a market-based solution to habitat and species loss.
What is BNG?
BNG became mandatory for major developments across England on the 12 February 2024, and on small sites from the 2 April 2024. BNG compliance for Nationally Significant Infrastructure Projects is expected to come into effect in late 2025. Some small scale applications, including householder applications, are exempt from BNG requirements.
BNG functions as follows:
- In England, BNG is required as a mandatory pre-commencement condition. A Biodiversity Gain Plan must be submitted to and approved by the local planning authority (LPA), demonstrating at least 10% increase in biodiversity value relative to the ‘pre-development’ value of onsite habitats.
- This gain can be achieved by developers through one of three methods: on-site habitat creation, off-site biodiversity gain (either on land outside the application site owned by the developer, or through purchasing offsite biodiversity units on the market), or if on-site and off-site BNG are not possible, the developer can purchase statutory biodiversity credits from the government
- Developers can utilise any combination of the above methods, but must attempt to deliver BNG according to the hierarchy: onsite > offsite > credits
- Habitat enhancements must be maintained for at least 30 years after completion of development, utilising planning conditions, section 106 agreements, or conservation covenants
- The LPA is expected to monitor on- and off-site gains secured by planning obligations, and to consider enforcement action if obligations are not being met
How is the policy currently working?
BNG has the potential to be a very powerful tool for improving biodiversity, but the RTPI has repeatedly expressed concerns over lack of guidance and resourcing, particularly within local authorities, that could hamper the effectiveness of BNG. Latest figures showed that 41% of local authorities were concerned about having enough ecological expertise to effectively manage BNG requirements.
The RTPI has also made the case for BNG exemptions on derelict and vacant land in areas of precarious development viability, to mitigate the impact of BNG on regeneration policy. While no changes of this kind have happened, BNG on brownfield sites is an ongoing issue that we will continue to monitor.
The overall design of the policy mechanism is a process-driven approach, based on a protocol and set of metrics, rather than one based on outcomes. The RTPI feels that there are limitations to this approach, and its success relies on a proper understanding of the metrics as well as consistent and thorough monitoring of compliance – the policy will only deliver on its aims if it is implemented fully and properly. Existing guidance on the failure to comply with BNG obligations is limited and relies on existing, under-resourced enforcement teams taking on the responsibility of continuous monitoring.
One solution to this situation could be the introduction of an obligation for developers to proactively report to the LPA with updates on the implementation and monitoring of their scheme. This would reduce the burden on planning enforcement teams.
Furthermore, the RTPI has argued for the integration of BNG with land use policy, advocating for Local Environmental Improvement Plans (LEIPs), which build upon Local Nature Recovery Strategies (LNRSs). LEIPs would ensure BNG is more closely tied to a strategic approach to nature recovery and habitat creation and protection. There is great potential in bringing private money into nature recovery, but a holistic approach to ecosystem services is essential to getting the maximum benefit from this policy mechanism.
Why now?
Since the introduction of mandatory BNG for major and small sites, there have been significant reforms to planning policy, and changes to legislation provisioned through the Planning and Infrastructure Bill. In particular, the Government’s plans for nature recovery, along with the adoption of Local Nature Recovery Strategies across planning authorities, could have significant impacts on the implementation and success of BNG.
Furthermore, any issues with BNG implementation and monitoring will only become apparent once sites with BNG obligations are built out. This means that there must be ongoing appraisals of the process to build upon our understanding of the policy’s strengths and limitations.
It is crucial that we continue to keep an eye on BNG amid continued planning reform so that consideration of biodiversity and ecology remains central to planning decisions.
What do we want to see, and how will this help?
The RTPI is calling for:
- The government to mandate the integration of BNG with spatial approaches to nature recovery, including Local Nature Recovery Strategies
- Introduction of a mandatory requirement for developers to proactively report their BNG implementation and maintenance progress
- Continued monitoring of BNG at a national level to continue to understand trends & issues
