Mandatory Biodiversity Net Gain (BNG) came into force in February 2024, and for small sites from April 2024. Natural England (on behalf of Defra) commissioned Eunomia to conduct a policy evaluation of BNG covering the initial period of the policy rollout through to a post-mandatory BNG evaluation (2023-2025). This report comprises the final policy evaluation circa one year on from BNG becoming mandatory.
The evaluation included a process evaluation, to understand the extent to which the BNG policy is being implemented effectively, and an impact evaluation, to understand the extent to which the policy is achieving its stated objectives. The report also presents a Value for Money (VfM) analysis of the costs and benefits sufficiently calculable at this early stage and suggests approaches for a future VfM evaluation.
The evaluation formulated twenty-four evaluation questions and employed the following data collection methods:
- Survey
- Fourteen focus groups
- Thirty semi-structured interviews
Overall, BNG processes are in place and functioning effectively, although there remain some challenges for stakeholders, especially related to capacity and experience in using the BNG tools and services. As few developments have been completed under mandatory BNG, its impact to date has been difficult to assess. However, while some implementation challenges exist, overall BNG is considered beneficial; it is already leading to the earlier and standardised consideration of ecological implications in development, and stakeholders felt that BNG is an advancement in both habitat preservation and compensation for habitat loss.
Most survey respondents and interviewees were optimistic about BNG delivery supporting local environmental priorities.