Biodiversity Net Gain: the new metric

Defra (Department for Environment, Food and Rural Affairs for England) and Natural England last week published the latest version of their Biodiversity Metric. This is important because it is the way we will measure Biodiversity Gain when the new planning requirements set out in the Environment Bill become law. It should be of vital interest to everybody involved with development in England, and to anybody who might be interested in new market opportunities to provide biodiversity gain sites.

The Environment Bill includes a major new element of planning legislation. All future development in England will have to demonstrate Biodiversity Gain, comparing the value of site biodiversity before the development with what has been left and enhanced afterwards. There will be exceptions. Details of these are not available yet. The Bill sets out the requirement for a gain of 10%, but this figure can be changed in future. It will also be possible for developers to buy Biodiversity Credits from the government as an alternative to the physical achievement of biodiversity gain. The Bill however requires that these should be set at a discouragingly expensive level.

The new Metric is version 3.0 and there have been some important revisions to the previous version, which is already in use for some projects. Defra advises that where version 2.0 is already being used for a project it should continue to be used.

There is now also a small sites version of the metric. Small is indeed fairly small. The maximum size site that can be considered is 0.5 ha, although for residential development of between one and nine houses the site can be larger, 1.0 ha. This will catch a lot of farmyard conversions. It might also suggest that the exceptions – sites which will not have to demonstrate biodiversity gain – are likely to be very small indeed. The Small Sites Metric does not accommodate offsite biodiversity gain, so even for smaller sites the main metric will still have to be used.

On Friday 16 July 2021 we will be taking a close look at the two new metrics, studying some worked examples and deriving the implications for professional practice, in our online #RuBrief session. This will run from 09.30 to 11.00 London time. Booking details here:

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