Defra has launched a consultation on making mandatory the delivery of a ‘net gain for Biodiversity’ within development sites.

Consultation has been opened on the mandatory delivery of a ‘net gain for biodiversity’ within development sites. A 10% gain in biodiversity (calculated in biodiversity units) is proposed over the baseline position.

A revised metric (Defra metric 2.0*) will be utilised to calculate the gain, which will be made available in due course within a spreadsheet based tool for use by ecologists. The consultation sets out that:

“Defra metric 2.0 will continue to be habitat focussed and retain the same core approach to calculating biodiversity unit value as the original metric. It will now, however, flexibly incorporate green infrastructure features (such as green roofs and street trees) and rivers into the metric and allow for greater sensitivity of habitat condition and distinctiveness scoring. It will also include measures to take better account of spatial factors, including an updated ecological connectivity component”.

The metric however is habitat centred and does not account for effects on individual species. The consultation sets out that “We are exploring approaches that allow net gain to deliver for individual species impacted by development and will look to bring these into scope over time”.

A preference is indicated for delivery of a net gain on site, but if this is not possible it can be delivered offsite, with local delivery incentivised: “We propose that a spatial hierarchy underlines the design, updating and operation of the entire net gain approach. This would mean that, where possible, biodiversity units should be delivered on site. Those that cannot viably be delivered on site should be delivered locally, according to a local plan or strategy. Where suitable compensatory habitats are not available locally, then investment in national conservation priorities may take place through a tariff”.

Should developers choose to buy into the tariff, this is likely to be set in the range of £9,000 to £15,000 per biodiversity unit and reflects “the costs of creating and managing compensation habitat in a suitable location” while seeking to “strongly incentivise the protection of existing habitats and encourage suitable local compensatory habitat creation when necessary”.

Further details of the consultation can be found here which closes on 10 February 2019. Natural England has produced a promotional video to support the process.


* Government has previously considered how losses of nature through development can be stopped and habitats enhanced. Defra ran six ‘biodiversity offsetting pilots’ between 2012 and 2014. The pilots contributed to our understanding of biodiversity measurement and policy. The pilots’ evaluation, however, found that a voluntary approach was not sufficient to deliver net environmental benefits or a level playing field for developers.