Biodiversity Net Gain

The Biodiversity Net Gain (BNG) principle establishes the simple objective of achieving a greater diversity of plants and animals after development has taken place than was present before. The concept is key to implementation of the UK Government’s stated policy objective to leave the environment in better condition when we pass it on than it was in when we inherited it. It can be demonstrated in a simple equation as follows:

Biodiversity equation

This requirement to achieve quantified BNG marks a step change in the regulatory approach to environmental protection, the focus shifting away from species protection and towards habitats and ecosystems.

The mitigation hierarchy

The mitigation hierarchy is a framework for managing risks and potential impacts related to biodiversity and ecosystem services.

In practice this means that developers may have to scale down their development design ambition to accommodate natural habitat or redesign their site to accommodate green infrastructure. In many cases, delivering BNG on-site may simply not be technically possible or adequate and developers will be obliged to seek off-site compensation (‘offset’ – see below) although planning authorities will expect compensation to be located close to the site of habitat loss and will penalise strategies that fail to do so.

How is Net Gain measured?

Planning policy requires achievement of an uplift in biodiversity as measured using a biodiversity metric such as Natural England’s Biodiversity Metric 2.0. Tools such as these are used to assess the baseline ‘biodiversity unit’ value of a site, and then to calculate the predicted unit value of the developed site based on the proposed layout. It allows different on-site and offsite compensation scenarios to be modelled and the creation and long-term management costs to be compared.

Standards and Good Practice Principles

Middlemarch Environmental expert ecologists have worked on the development committee of British Standard BS8683: Process for designing and implementing Biodiversity Net Gain’, alongside other professionals in engineering, national and local government and industry bodies. The standard provides a specification for the design and implementation of BNG for development and land management of an estate. It applies throughout the lifecycle of projects of any scale, for any sector of industry, including residential, mixed-use, energy, water, transport, communications and infrastructure from initial feasibility study to post-construction management and maintenance. It may also be used for Whole Estate Management by landowners seeking to enhance their natural capital and ecosystem service benefits of their assets.

In advising clients we adhere to the principles set out in joint CIEEM/CIRIA/IEMA document ‘C766a Good Practice Principles for Development’.

Biodiversity Offsetting

Where achieving biodiversity net gain is not possible on site whilst still delivering a viable project, developers have the option to contribute at a local or regional scale to off-site Offsetting or Compensation. This approach can often successfully result in greater gains for biodiversity than could be provided within a constrained development site. It supports delivery of Local Nature Recovery Strategies and is consistent with the central conclusion of Professor Sir John Lawton in his 2010 report ‘Making space for nature’, that we need more, bigger, better and joined up habitats. Middlemarch Environmental works with our clients to identify off-site mitigation solutions and, as a result of our unique relationship with Warwickshire Wildlife Trust, we can design and implement offsetting solutions, including long-term management plans, on land that would generally be inaccessible to developers.

The services we provide include:

Baseline biodiversity assessment:

  • Baseline ecological surveys
  • Calculation of Biodiversity Units on development and offset sites
  • BNG options appraisal
  • Any scale from single unit to whole estate and portfolio

Feasibility Study & BNG solution design

  • Expert habitat design services
  • Biodiversity Enhancement Strategy
  • Soft landscape design and planting plan
  • 30 Year Habitat Management Plan
  • Consideration of Green Infrastructure Plans and Local Nature Recovery Strategies

 BNG Scheme Implementation

  • Identification of land for offsetting / compensation
  • Liaison with local planning authorities and other relevant stakeholders
  • Contractor engagement
  • Materials procurement
  • Programme management
  • 30 years + Management