top of page

Biodiversity Net Gain: Methodology 


Wallace Darwin Environments will produce quality assessments of your proposals. Our dedicated team of experts will rigorously analyse your plans following 4 key steps:

Survey of baseline habitats and condition:


The proposed site of development's baseline habitat typing and condition assessments are undertaken during Preliminary Ecological appraisals (PEA), additional visits and desktop study (satellite imagery, previous ecological reports).


Calculations of baseline habitats:


Using Geographic Information Software (GIS), baseline habitats are measured in hectares (ha) and input into the DEFRA Biodiversity metric  Calculation tool (or similar depending on local planning authorities' (LPA)  needs) or for small sites the DEFRA Small Site Metric tool. Each habitat has a base score of 1, this is then multiplied by the size of the habitat (ha). The habitat is then multiplied by its distinctiveness, condition, connectivity and strategic significance. 

Calculations of post development habitats:


The calculation is informed by planning design, landscape plans, and proposed ecological mitigation. Plans are georeferenced into GIS with measured in hectares (ha) and input into the DEFRA Biodiversity metric Calculation tool (or similar) or the DEFRA Small Site Metric tool. From here the development can be assessed to see if it will result in a net loss, no net loss or a net gain for biodiversity.


If your development results in a net loss or no net loss, Wallace Darwin will provide further recommendations and a bespoke layout plan to in order to hit the target Net Gain, create habitat for wildlife and suit the needs of the development. Recommendations will take into account any recommendations made in previous reports such as bat activity report. 

On top of this Wallace Darwin will provide you with a  management plan detailing when to how to create the recommended habitats, when implement them and when to manage them. A time table of when new habitats are to be monitored to see if they have met target conditions over the mandated 30 year period will also be provided. 

Green Park
Green Roofs
Image by Scott Graham
bottom of page