As of mid-2025, Biodiversity Net Gain (BNG) has moved from policy to practice, bringing significant changes for landowners and housebuilders across the UK. Under the Environment Act 2021, most new developments in England are now legally required to deliver at least a 10% uplift in biodiversity compared to the site’s pre-development baseline. This BNG mandate became effective for major planning applications in February 2024, extended to small sites by April 2024, and is set to apply to Nationally Significant Infrastructure Projects by late November 2025.

BNG Implementation: Current Status and Guidance (2025)

BNG is now a mandatory part of the planning regime, meaning new planning permissions in England typically come with a condition to achieve a minimum 10% net gain in biodiversity value. To comply, developers must submit a biodiversity gain plan alongside planning applications, detailing how post-development habitat value will exceed the pre-development value by the required 10%. This plan is underpinned by DEFRA’s Biodiversity Metric, a standard calculation tool (now at version 4.0) which quantifies habitat “biodiversity units.” A tailored Statutory Biodiversity Metric (and a simplified Small Sites Metric for minor projects) must be used to assess losses and gains. In practice, an ecologist usually surveys the site to calculate baseline units, and developers then propose on-site habitat enhancements or off-site measures to ensure a net gain. Local planning authorities will refuse or delay approval if an adequate biodiversity gain plan (including the metric calculation) is not provided and approved. Notably, any BNG achieved must be secured for at least 30 years via planning obligations or conservation covenants, with long-term management plans in place. Failure to deliver the committed gains can result in breaches of planning conditions and enforcement action, underlining how seriously authorities are treating the new rules.

Practical Implications for Developers and Landowners in Planning

For housebuilders and developers, mandatory BNG means that ecological considerations need to be incorporated into planning applications from the outset. Following calculation of baseline biodiversity units, developers must identify how to achieve a +10% net gain, which could involve redesigning site layouts to retain valuable habitats, creating new habitats (like parks, woodlands, wetland features) on the development site, or arranging for off-site habitat creation on other land. The key is that developers who proactively plan for BNG can not only avoid delays but also potentially create more attractive developments. Green spaces and biodiversity features can enhance aesthetics and community value, aiding to a more sustainable development and gaining public and council support.

From the landowner perspective (including strategic land promoters and farmers), BNG brings both new responsibilities and opportunities. Landowners bringing forward land for development must be aware that a portion of the site (or an equivalent off-site area) will likely need to be allocated for biodiversity enhancements. This might slightly reduce the net developable acreage or require setting aside adjacent land for habitat, which could affect land value if not planned for. However, through our specialised services at Hex, this can be turned this into an opportunity: by demonstrating a BNG strategy upfront (for example, showing where habitat will be improved to achieve net gain), landowners can make their site more appealing to planning authorities and developers. Incorporating BNG early can de-risk the planning process and show commitment to sustainable development, which is increasingly important in local plan considerations.

In regions like Cheshire, which feature a mix of agricultural land and valuable natural habitats, landowners are also exploring habitat banking, creating biodiverse habitats on part of their holdings to sell off-site BNG units to developers unable to meet the 10% on their own site. This can generate income while the land remains under the landowner’s control (subject to the 30-year management agreement). For example, Cheshire Wildlife Trust’s Saltersford Farm project (Holmes Chapel, Cheshire) is an illustrative local case: a former 19-hectare farm is being restored to nature, producing ~47 biodiversity units that are sold to developers under Cheshire East’s local BNG policy. Such initiatives show how landowners in the North-West can capitalise on BNG by partnering with conservation organisations or developers to deliver off-site gains. The practical takeaway is that both developers and landowners should factor BNG into land deals and project budgets, including costs for ecology consultants, habitat works, and legal agreements, and should start these discussions early to avoid surprises later in the planning stage.

Opportunities and Risks for Strategic Land Development under BNG

With BNG now embedded in the planning system, strategic land developers and landowners need to navigate a new landscape of opportunities and risks:

Opportunities

• New Revenue Streams: Creating or enhancing habitats to sell biodiversity units can provide landowners with diversified income. If you have land unsuitable for built development, it could be used for BNG projects, effectively monetising conservation efforts. Local Nature Recovery Strategies in areas like Cheshire can guide where habitat creation will be most valuable, aligning environmental goals with profit.

• Added Planning Value: Development proposals that clearly integrate BNG are likely to stand out in planning. Showing how a project delivers net gain, e.g. including green corridors, wildflower meadows, or ponds, can make planning applications more compelling and policy-compliant. This can speed up permissions and even improve community support.

• Partnerships and Land Deals: BNG requirements encourage collaboration. Housebuilders with constrained sites can partner with local farmers or landowners to deliver off-site BNG nearby, creating business relationships. In the North-West, where rural land surrounds growth areas, this opens the door for agreements where a landowner provides habitat (and gets paid for it) while a developer meets their obligations. There are emerging brokerage services and registers to connect developers needing units with land managers offering them, which strategic land consultancies like Hex can help navigate.

Risks and Challenges

• Increased Costs and Land Take: Achieving BNG isn’t free – it often requires sacrificing land that could have been developed or investing in habitat works and long-term management. For large sites this may be manageable, but small development sites could struggle to accommodate on-site BNG, forcing them to purchase units off-site. This adds cost and complexity to projects. Developers need to budget for BNG implementation (e.g. specialist surveys, landscaping, maintenance) early on.

• Market Uncertainty: The off-site BNG unit market is still maturing. Early evidence suggests demand for purchased units has been lower than initially expected, possibly because many big developers are managing on-site gains and some smaller projects are yet to enter the system. This unpredictability in demand and pricing means landowners creating habitat banks must be cautious – returns might take time, and prices per unit can vary by location and habitat type. It’s a new market, so there is a risk in investing heavily in habitat creation without guaranteed buyers.

• Regulatory Complexity and Compliance: Navigating the technical requirements of BNG can be challenging. The DEFRA metric calculations, securing legal agreements, and ensuring 30-year management can be daunting for those unfamiliar. Mistakes or miscalculations could lead to planning refusals or enforcement if net gain targets are not actually met in practice. There’s also the possibility of policy changes: since BNG is in its early stages, government guidance may be refined (for instance, clarifying “trading rules” for what habitat losses can be compensated by which gains, or changes in metric versions). At Hex we will stay updated on the latest DEFRA/Natural England guidance to remain compliant and take advantage of any new incentives.

• Local Policy Variations: While 10% net gain is the national baseline, some local authorities or upcoming Local Nature Recovery Strategies might push for higher gains or specific habitat priorities. For example, local wildlife trusts in Cheshire have argued for 20% net gain in recognition of the ecological crisis. This could translate into stricter requirements in certain local plans or for certain sensitive sites. Hex will ensure to remain on top of local plan consultations and emerging policies in the North-West to ensure our strategies align with any above-national requirements. Not meeting local expectations could pose a risk to securing planning permission.

Conclusion

In summary, Biodiversity Net Gain is now fully in force as a transformative factor in land development. Landowners and housebuilders in the North-West and Cheshire are already experiencing the practical impacts: planning applications now demand careful ecological planning, and there are new business models around habitat creation and unit trading. By understanding the current BNG regulations, from the DEFRA metric to the 30-year management rule, and by proactively engaging with local policy and partnerships, Hex can turn this environmental obligation into an opportunity. The transition has its challenges, but those who integrate BNG early will be best placed to secure permissions and add long-term value to their projects. As always, staying informed through official sources (e.g. DEFRA’s guidance, Natural England’s updates) and seeking specialist advice when needed will be crucial. With Hex’s specialised services, BNG promises not just regulatory compliance but a chance to contribute to a nature-positive future while still achieving development goals.