Learn about Net Benefit for Biodiversity in Wales – what it is and how it’s achieved.
Last updated: 2 July 2025
Net Benefit for Biodiversity (NBB) was introduced by the Welsh Government as a result of the United Nations COP15 Biodiversity Summit in 2022. After completing its own Biodiversity Deep Dive, a set of actions to protect our most important habitats and support nature’s recovery were developed.
Planning Policy Wales (PPW) defines a net benefit for biodiversity as ‘the concept that development should leave biodiversity and the resilience of ecosystems in a significantly better state than before, through securing immediate and long‑term, measurable and demonstrable benefit, primarily on or immediately adjacent to the site.’
The Environment (Wales) Act 2016 introduced a duty (the Section 6 Duty) that requires local planning authorities (LPAs) to seek to enhance biodiversity through the planning process and promote the resilience of ecosystems.
In 2019, Welsh Government’s Chief Planner provided guidance on the application of the Section 6 Duty with regard to securing biodiversity enhancements. The guidance also stated that if NBB cannot be achieved, planning permission should be refused. PPW was then updated to reflect this, to improve the resilience of ecosystems and strengthen policies in relation to green infrastructure and designated sites such as Sites of Special Scientific Interest (SSSIs).
Natural Resources Wales (NRW) has developed a framework for evaluating ecosystem resilience
based on five aspects that are set out in the Section 6 Duty. This is referred to as DECCA: Diversity, Extent, Condition, Connectivity and Adaptability of ecosystem resilience. The framework can be applied across different habitats and land uses and for a range of different scales. Learn more about the DECCA framework in PPW (pages 146-147).
In practice, this means that a planning application should consider the possible effects of the proposed development on the diversity, extent, condition and connectivity of ecosystems within and beyond the site and look to improve them as part of the NBB.
Most developments that apply for planning permission must provide and demonstrate that they have both maintained and enhanced biodiversity and built resilient ecological networks through green infrastructure.
Biodiversity enhancements that achieve NBB must be delivered following implementation of the step wise approach, also known as the mitigation hierarchy, of firstly avoiding, then minimising, mitigating and as a last resort compensating for, adverse impacts on the environment arising from a development. Read more about this in PPW (paragraph 6.4.15 and Figure 12, pages 148-149).
NBB can be achieved through small-scale actions such as bat and bird boxes to large-scale creation or restoration of habitats. The Chief Planner’s letter emphasises that NBB does not ‘need to be onerous’ and should be proportionate to the extent and impact of the development. Small scale interventions are important as they contribute to a national scale resilience. The purpose of NBB is for development proposals of all sizes to contribute to a more resilient and biodiverse ecological network in Wales.
Planning applications must show how the step wise approach and DECCA framework have been used to achieve a net benefit to biodiversity and green infrastructure in a Green Infrastructure Statement, which is required for all developments.
To learn more about NBB, take a look at this guidance from the Welsh Government.
If anything concerns you about a development’s biodiversity proposals, don’t hesitate to get in touch with your LPA who are responsible for ensuring the proper implementation of NBB and the Section 6 Duty.