Biodiversity net gain legislation and what it means for developers

The UK is one of the most nature-depleted countries on Earth. According to the State of Nature Report published in 2023, nearly one in six species is threatened with extinction, with an average population decline of 19% since 1970 across the 753 species studied.

This decline in biodiversity has occurred alongside a growing awareness of nature’s value, and the critical role it plays in managing the range of ecosystems that allow our planet to function, and in mitigating and adapting to the impacts of climate change.

The construction and operation of new developments is a key contributor to this biodiversity decline. New developments often lead to habitat destruction, fragmentation of ecosystems, water and air pollution, and resource exploitation which results in a significant loss of biodiversity and the degradation of natural ecosystems.

The new Biodiversity Net Gain (BNG) legislation hopes to address these issues. As of February 2024, the new regulations require at least a 10% increase in biodiversity for all major developments in England, with small developments being included from April 2024.

What is BNG and how can it be achieved?

BNG is an approach to development that ensures that wildlife habitats are left in a measurably better state than before the development.

For BNG, biodiversity is measured in standardised ‘biodiversity units’, with an individual habitat containing several biodiversity units depending on its size, quality, location and type. Biodiversity units can be lost through development or generated through work to create and enhance habitats.

Developers are encouraged to follow a hierarchy of measures to minimise their impact on the environment and achieve BNG:

1. Avoid biodiversity loss through site selection and layout.
2. Enhance biodiversity on-site through habitat creation within the red-line boundary.
3. Enhance biodiversity off-site by creating habitat on the developer’s own land or buying biodiversity units on the market.
4. Purchase statutory biodiversity credits from the government as a last resort. The government will then use this revenue to invest in habitat creation in other locations across England.

If a development needs to meet the mandatory BNG requirements, BNG must be calculated using the government’s statutory biodiversity metric tool in consultation with a professional ecologist.

The new BNG requirements have been generally welcomed by the wildlife sector. However several organisations have expressed concerns regarding the effectiveness of BNG measures to protect and regenerate degrading habitats, and the capacity of local authorities to deliver on the new requirements.

On reviewing the legislation, the Wildlife Trust is concerned that “Biodiversity Net Gain is not currently on track to play its part in addressing the severity of the continuing nature crisis – and that current ambition is set too low”.

The Royal Society for the Protection of Birds believes that the list of irreplaceable habitats - habitats that take many years to create and, therefore, cannot simply be replaced – is too short. If we are to reverse the UK’s rapid decline in biodiversity, the list will need to be significantly extended to include other habitats, such as hay meadows and chalk grasslands.

Key takeaways for developers:

1. A minimum 10% gain in biodiversity credits is required for all major developments, calculated using the statutory Biodiversity Metric Tool.
2. A ‘biodiversity gain plan’ must be submitted to the Local Planning Authority (LPA) alongside the metric tool calculation. The LPA will then approve or refuse the plan within eight weeks.
3. The landowner is legally responsible for creating or enhancing the habitat and managing that habitat for at least 30 years from the completion of the development.
4. Habitat loss must always be avoided during development work. If this is impossible, a developer can achieve an overall BNG on-site or off-site or as a last resort by buying statutory biodiversity credits.

The UK’s BNG legislation represents a significant step forward in addressing the continued decline in biodiversity. While the legislation is a positive development and has the potential to mitigate some of the losses, its effectiveness in fully reversing the UK’s decline in biodiversity remains uncertain.

Continued monitoring, adaptive planning and a holistic approach that integrates biodiversity considerations into wider environmental and land use policies will be essential in addressing the complex challenges facing biodiversity conservation in the UK. As an industry, we should continue to review legislation to assess whether the 10% requirement is sufficient, as well as expanding the list of irreplaceable habitats to ensure that any losses are accounted for and improved upon.