BNG and NBB
Biodiversity Net Gain (BNG) is an approach devised by the UK government to ensure that habitats for wildlife are left in a measurably better state after development. It is mandatory in England under Schedule 7A of the Town and Country Planning Act 1990 (as inserted by Schedule 14 of the Environment Act 2021). Developers must deliver a BNG of 10% which means that a development will result in more or better quality natural habitat than there was before development.
The process begins with a desktop study to establish the habitats and conservation areas on site and in the local area. A physical survey is then carried out on site where habitats and their conditions are inspected and graded according to the BNG metric.
A BNG assessment can be carried out at any time of year but it is preferable to conduct surveys during spring and summer when flora on site is most apparent. A report is produced detailing the current biodiversity value and the biodiversity units needed for sufficient gain to satisfy the metric.
In Wales the BNG metric is not required. However, the Net Benefit for Biodiversity (NBB) framework is defined by Planning Policy Wales as 'the concept that development should leave biodiversity and the resilience of ecosystems in a significantly better state than before'. The Environment (Wales) Act 2016 introduced a duty for biodiversity to be enhanced through the planning process and guidance states that if NBB cannot be achieved then planning permission should be refused.