The type, condition, and area of habitats on site are determined prior to the development. Then, each habitat included in the proposed development is calculated, with each habitat assessed on its condition and size too.

This habitat data, along with information on local biodiversity action plans, are input into the Biodiversity Metric (versions are currently being updated regularly), which results in the calculation of Biodiversity Units. The different between the baseline and proposed development biodiversity units provide a percentage – this is the Biodiversity Net Gain.

With a minimum of 10% biodiversity net gain needed for a development to be approved, we then recommend the best ways in which to achieve this.

For example, on a recent project, the biodiversity net gain was calculated for the proposed development where a +8.96% net gain was achieved. Therefore, to meet the minimum 10% net gain, a further +1.04% was needed.

We recommended using a species-rich grass seed mix, such as WFT-Species-Rich-26, for the proposed amenity grassland. We calculated that enhancing 0.8 Ha of the proposed amenity grassland would meet the minimum 10% net gain. Another option was to include patches of mixed scrub, totalling at least 0.1 Ha, which would also meet the 10% net gain requirement.

A Biodiversity Net Gain calculation and subsequent report can be carried out any time of the year.