Biodiversity Net Gain

Biodiversity is the variety of life on earth and Net Gain is an overall measurable improvement. Biodiversity Net Gain (BNG) is not about replacing, but about improving and enhancing the variety of life. It is one form of ecological enhancement.

The rapid degradation of habitat and species biodiversity has led policy makers to seek solutions. BNG is development that leaves biodiversity in a better state than before, requiring a 10% increase in biodiversity after development, compared to the level before. It is an approach where developers work with all stakeholders to support their priorities for nature conservation.


In England, BNG is now mandatory and planners must deliver a BNG of 10%.

How it works

  • The developer uses DEFRA’s Biodiversity Metric tool to calculate the pre-development biodiversity units and a projected post-development value
  • Any proposed development resulting in a biodiversity loss (taking into account the mandatory 10% uplift) will have to source the missing biodiversity units
  • Additional biodiversity units can come from habitat enhancement onsite or offsite

Quants Environmental has suitably qualified and experienced Ecologists (SQEs) able to assess the biodiversity of a site and calculate its value, including using the DEFRA Biodiversity Metric. It is important to involve the SQE at the earliest stage of development. Our Ecologists have experience in habitat creation and the provision of long-term biodiversity management plans, as well as knowledge of local planning requirements within Yorkshire and the Yorkshire Dales, Derbyshire, Teesside and Tyneside.


These 10 principles set out good practice for achieving Biodiversity Net Gain and must be applied all together:

  • Apply the mitigation hierarchy – do everything possible to first avoid and then minimise impacts on biodiversity
  • Avoid losing biodiversity that cannot be offset by gains elsewhere – avoid impacts on irreplaceable biodiversity
  • Be inclusive and equitable – Involve stakeholders early in designing, implementing, monitoring, and evaluating the approach to BNG
  • Address risk – Apply well-accepted ways to add contingency when calculating biodiversity losses and gains
  • Make a measurable net gain contribution
  • Achieve the best outcomes for biodiversity
  • Be additional – do not deliver something that would occur anyway
  • Create a net gain legacy – think long term
  • Optimise sustainability – optimise the wider environmental benefits
  • Be transparent – share what you are doing and why

If there is one take home message, it is to get your Ecologist involved early and use the 10 principles above to stay on track.