This blog article summaries the core issues and potential solutions discussed in CIEEM’s report, “BNG for Small Sites: Delivering on its Potential.“
In April 2024, England saw the introduction of mandatory Biodiversity Net Gain (BNG) requirements for minor developments, following its earlier application to major projects. This policy shift aims to ensure that nearly all developments positively impact biodiversity, marking a significant departure from decades of ineffective “no net loss” policies. However, as the new legislation unfolds, the implementation of the Small Sites Metric (SSM) has raised critical questions about its efficiency and fairness, particularly for smaller developments.
What Is the Small Sites Metric?
The Small Sites Metric (SSM) is a specialized tool designed to simplify the process of assessing biodiversity impacts and planning gains for minor developments. These include residential projects with up to nine units or small commercial developments under specific size thresholds. The SSM was intended to streamline the process while ensuring that small sites contribute to the broader goal of halting biodiversity loss and fostering nature recovery.
While the concept aligns with the overarching goals of BNG, practitioners have reported significant challenges in its implementation.
Challenges with the Small Sites Metric
1. Disproportionate Burdens
For many developers, the administrative and legal requirements of the SSM feel excessive relative to the biodiversity benefits achieved. The complexity of using the metric, particularly for small-scale projects, has led to concerns about disproportionate costs and time commitments.
2. Issues with On-Site Gains
One of the most pressing issues is the difficulty of achieving meaningful biodiversity gains on smaller sites. For example, private gardens, often classified as low-value habitats, do not allow for significant contributions to biodiversity. Developers are frequently forced to seek off-site biodiversity units or statutory credits, which are expensive and not readily available.
3. Capacity and Expertise Shortages
The introduction of BNG has intensified pressure on an already overstretched ecology sector. Smaller ecological consultancies, in particular, struggle to keep up with the demand for assessments and reporting, while local planning authorities face increased workloads due to the complexity of processing small-site applications.
4. Baseline and Metric Accuracy
Practitioners have reported inconsistencies in baseline habitat assessments, especially when conducted by non-specialists. These inaccuracies can inflate the required biodiversity gains, further complicating the process and leading to delays and disputes.
5. Cost Concerns
For developers of small sites, particularly those working on lower-value projects, the costs of ecological assessments and compliance with BNG requirements are viewed as prohibitively high. This creates frustration and sometimes leads to the selection of less experienced consultants offering cheaper but lower-quality services.
Proposed Solutions
The Chartered Institute of Ecology and Environmental Management (CIEEM) has identified several key reforms to address the issues associated with the SSM and make BNG for small sites more effective and equitable:
- Adjusting the De Minimis Threshold
Excluding very small developments (e.g., one or two housing units) from BNG requirements could reduce administrative burdens and associated costs without compromising biodiversity goals. - Simplifying the Metric
Modifications to the SSM could better account for the unique challenges of small sites. For example, wildlife-friendly gardens, small ponds, and tree planting should be recognized as legitimate on-site gains. - Introducing a Biodiversity Tariff
A fixed payment system managed by local authorities or Local Nature Partnerships could streamline the process for developers, improve cost predictability, and fund local biodiversity projects. - Increasing Habitat Banking Options
Establishing more local habitat banks offering fractional biodiversity units at accessible prices could alleviate the difficulties developers face in securing off-site credits. - Providing Training and Resources
Enhanced training for planners, developers, and ecological consultants could ensure accurate use of the SSM and foster better integration of BNG principles into small-site design.
A Path Forward
The introduction of mandatory BNG is an ambitious and groundbreaking step toward halting biodiversity loss in England. However, the challenges faced by developers, planners, and ecological consultants in implementing the Small Sites Metric highlight the need for iterative improvements.
By addressing these concerns and adopting the solutions proposed by CIEEM and other stakeholders, the SSM can fulfill its potential as a tool that balances development with nature recovery. Collaboration, innovation, and a willingness to adapt will be essential to ensuring that BNG becomes a success story for biodiversity and sustainable development alike.
