Baker Consultants

Biodiversity Net Gain is a gamechanger for wildlife, land prices & so much more

The Environment Bill has returned to the House of Commons after a rather long hiatus.

Deep within the Environment Bill are measures which are designed to halt the continuing decline in the diversity and extent of the England’s wildlife. In this article, Baker Consultants’ Managing Director, Andrew Baker shares his thoughts on the wide ranging impacts that Biodiversity Net Gain will have on land ownership, land development and land stewardship.

As many will already be aware the bill introduces a new phrase to our lexicon ‘Biodiversity Net Gain’ or BNG. If you haven’t heard of this already, you will soon, and the impact of BNG promises to be the most significant and far reaching change to nature conservation law in 40 years.

Against a background of failure to halt the decline of wildlife over the past 40 years, DEFRA launched a consultation on a radical new approach which would introduce mandatory requirements to the planning system in England to deliver measurable biodiversity net gain of 10%. It is these principles that have being incorporated into the Environment Bill which is now again progressing through parliament.

The Principles in Practice

BNG will be delivered through the planning system and all new projects (with only a few exceptions) that have any kind of land take will be required to deliver 10% biodiversity gain when compared to pre-development base line biodiversity value of the site. The 10% gain can be achieved through on-site measures such as provision of public open space that has a high biodiversity value, or enhancement of existing biodiversity features that are to be retained. If on site measures are not sufficient to achieve the gain then off-site gains will need to be secured. As with the onsite measures, this can be creation of new habitat or enhancement of existing habitat. Any measures will need to be secured through appropriate legal agreements to ensure both delivery and long-term management of BNG areas and the Environment Bill sets out some new legal structures which will support this.

Measurable net gains

At the heart of this new requirement is the mechanism for measuring biodiversity the ‘DEFRA Metric’. The Metric is a spread-sheet based tool which allows the quantification of the baseline value of a development site, and the BNG of the compensation measures. The spread sheet is based upon the areas of habitat present on the site with different values given to different habitat types. The area x the habitat value gives the overall value for that habitat expressed in ‘biodiversity units’ (BU). Additional ‘weighting’ is given depending on the condition of the habitat or its relationship with other habitats. Using the Defra Metric it is therefore possible to calculate the losses and gains for any development and ensure that the overall outcome achieves the required 10% improvement.

Because of the complexities of the Defra Metric these calculations are not something that a project QS can calculate but rather it requires the experience of a qualified ecologists to survey the development site, complete the conditions assessment and calculate the over figure in BUs.

Implications for land prices

It is the economic implications of BNG that are going to be most interesting. The Impact Assessment that accompanied the Environment Bill presents an analysis of likely cost of creating a biodiversity unit in the region of £11,000; to put this into context on one hectare of land it would be possible to create approximately ten biodiversity units by creating species rich grassland. Given this, it doesn’t take too much analysis to understand that creation of biodiversity units could offer a significant uplift to poor quality agricultural land which carries little commercial value. The Government envisages that the BNG will ultimately lead to local markets in biodiversity units with landowners offering land to the market upon which BUs can be created. This would create a market driven hierarchy where-by developers first seek to retain or create as many BUs onsite, before seeking land elsewhere upon which new BUs can be created and finally as a last resort paying BU credits to Government backed schemes that will use the money raised to create biodiversity.

It’s happening now!

While the Environment Bill allows for time for the introduction of mandatory BGN, unusually planning policy has stolen a march on the legislation. The National Planning Policy Framework (NPPF) was updated in 2018 to include the requirement for plans to ‘identify and pursue opportunities for securing measurable net gains for biodiversity’. As many local planning authorities update their local plans, policies are now emerging which require development to deliver 10% BNG and also refer to the Metric. For most projects we are now being asked by clients to provide the Defra Metric calculations for proposed projects and to see how we can deliver the required 10% net gain.

Whatever happens with the Environment Bill, Biodiversity Net Gain is already here and likely to stay. The development industry will need to respond quickly and look carefully at the costs but also the opportunities this will bring especially to those with larger land holding.


If you need advice on land management, planning or development, or in how biodiversity net gain will impact your plans, then please  get in touch with us via our contact form on the website, or you can call us on +44 (0)1629 593958 or email us on