Perspectives Regenerative Design

Biodiversity Net Gain (BNG) legislation moves closer - read our top tips to achieve BNG.

As the long-awaited legislation for Biodiversity Net Gain (BNG) of 10% for major developments comes into force on the 12th February 2024 for major sites and for small sites from April 2024, we will see for the first time a mandatory requirement in the planning system to make sure that wildlife habitats are left in a measurably better state than before the development.

England is one of the most nature-depleted countries in the world due to its long history of industrialisation, modern farming practices and population density, and this ambitious piece of legislation offers enormous potential to reverse this tide and ensure every major development makes a positive contribution towards combatting the biodiversity crisis.

BNG requires developers to provide at least 10% of the biodiversity value found on the site prior to their development, and in the case of some local authority’s higher gains of up to 20% are targeted. BNG can be delivered either fully or in part through on-site habitat (preferred), through off-site habitat creation, or as a last resort, the purchase of statutory biodiversity credits.

To calculate the gain the project ecologist will use the DEFRA BNG metric to measure the value of the habitats present on site in biodiversity units, considering the size, type, location and condition of the habitats present. For new created habitats the formula takes account of the difficulty and time to establish the habitats to their target condition, as well as the distance from the habitat lost. The legislation also includes a requirement to manage the habitat and monitor its condition for 30 years.

At Gillespies we have been working closely with our clients and project ecologists to implement the metric on sites large and small.

Rain Gardens and retained mature trees at Elephant Park © Gillespies/John Sturrock

In this article we take a look at what we have learnt so far and our top five Biodiversity Net Gain tips.

#1 Start the process early. Use the BNG metric to inform early design option selection to maximise gains and check at the outset if they can be achieved with the development proposed. At Tendring and Colchester Garden Community we supported the joint councils alongside master planners Prior & Partners and ecologists Tim Moya Associates as part of their local plan process to undertake a preliminary BNG assessment across the full strategic allocation of over 700 ha. This informed the selection of a preferred strategic masterplan option with compact neighbourhoods and large areas of natural green space.

#2 Think holistically- the focus on net gain is important but so is connecting into the wider nature recovery network in the locality. The aim is to create a network of connected habitats which have more resilience to climate change, and which can support a greater abundance of wildlife and species. At Bushfield camp in Winchester, we have worked alongside Thomson Environmental Consultants and master planners Make Architects on a site with existing areas of high ecological and landscape value, planning to create new chalk grassland and woodland, both of which are rare, to enhance habitat connectivity and increase resilience to climate change. When we connect landscape fragments together, they become much more resilient to extreme weather events, as species can move to areas that meet their requirement for survival.

Bushfield Camp, Winchester © AVR London

#3 Be careful of brownfield ‘open mosaic’ habitats- these can be ecologically valuable and often difficult to retain in schemes. In our work at Bromley by Bow Gasworks for St Williams Homes, we are proposing to replicate this habitat in the proposals, as retention is not an option due to the presence of contaminated land. Brown roofs can also be useful in these situations.

Bromley-by-Bow Gasworks Landscape Masterplan. © Gillespies

#4 Maximise the wider benefits of the 30 year management requirement Increasingly we see the long term 30 year management requirement of the BNG legislation benefiting our engagement work, helping to build community trust and confidence and secure long term management of open spaces for recreational as well as environmental benefit. Making space for community involvement, governance, and nature conservation skills training in the management plan can have wider benefits in helping to engender an increased sense of community care and nature connectedness, as well as upskilling the next generation of land managers tasked with managing the thousands of hectares of new habitats that will be created through this legislation.

#5 Collaborative team working and iterative testing is key- Achieving gains of more than 10% particularly on greenfield sites can be challenging depending on the habitats present and requires a collaborative design team response. We recommend undertaking preliminary assessment at an early stage and the design team following the mitigation hierarchy to avoid, minimise, restore and as a last resort offset loss. Early assessments will establish if the gain can be achieved on site or if offsite land will be needed, along with the opportunities for enhancement and the implications for future management, delivery and phasing. We recommend repeating the assessment a number of times to shape the proposals and optimise the gains.

New river terraces boost biodiversity at RAM Quarter © Gillespies

At Gillespies, we design with intelligence and foresight, harnessing the networks that govern the natural systems of which we are part. By doing so, we help to restore equilibrium in the environment, an essential outcome if we are to coexist with all living things on this planet.

If you have any questions about Biodiversity Net Gain or need support in navigating the challenges in your projects, please contact us.