How to Achieve Biodiversity Net Gain and Get Your Plan Approved

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(Last Updated 12th September 2023) 

Developers have known about Biodiversity Net Gain (BNG) for some time. So, they will know that, from this coming November, with only a very few exceptions, planning applications will only be granted on proof that their development site can show a minimum biodiversity net gain of 10% over the biodiversity value of the land before work starts. 

Many developers have already prepared for this, but many more have not. The Environmental Act 2021 becomes law in November 2023, when Biodiversity Net Gain becomes mandatory. 

First, let’s start by answering a fundamental question: How do you measure biodiversity?

The answer is Metric 4.0, a standard of measurement developed by Natural England and used by developers, local authorities, landowners, stakeholders, land banks and brokers, professional advisors, and government departments with responsibility for England’s environment. 

So, if you are not ready now, what can you do about it? When should you start to prepare? What is involved and from whom can you get help? 

How do you start?

As a developer, you will know that between the purchase of a site and the completed development, there are many fences to leap, one of them being planning permission. From November 2023, there is another fence: Biodiversity Net Gain, a mandated pre-condition for the granting of planning permission. In other words, an approved BNG plan is an essential preliminary to getting planning permission. You cannot gain planning permission without a BNG plan; there is no shortcut.

A BNG Plan

A BNG plan involves a great amount of detail unique to a particular project so, only the broadest brush sketch is possible. It is important to understand an approved plan will take time, money and professional help to put together. Here are the basic ingredients required:

  • A biodiversity survey of your site before work starts to value the habitat in terms of type (woodland, meadow, riverbank, heath etc), extent, location, environmental richness and condition. An experienced, qualified ecologist must complete surveysEcology by Design can help here.
  • A projection of the biodiversity value of the development site after completion.
  • The result of the survey(s) will determine what, in detail, is needed to meet the target biodiversity gain of 10%.
  • Some of the biodiversity loss may be achieved on-site by mitigating some, or all, of the degradation caused by the development. This could help reduce the target net gain.
  • Your BNG plan will further set out how you will achieve the target:


  1. Local planning authorities like to see a like-for-like biodiversity type being replaced either on-site or off-site. 
  2. Where the replacement habitats will be, the distance from your development site, their type, richness, rarity, physical state etc.
  3. How will the habitats be maintained or improved over a period of 30 years? who will be responsible for their management

Mitigation Hierarchy.

Your BNG plan may show that there is scope to achieve some, if not all, of the loss of biodiversity. A mitigation hierarchy is a necessary discipline to minimise the offset value needed to achieve a 10% Gain. So, following the biodiversity survey, you need to look at how to avoid the damage; then find ways and means to minimise that damage; then restore as much of the damage as possible before establishing the value of the offset required to reach the 10% gain.


Biodiversity offsets are defined as the measurable conservation outcomes of a developer’s actions to compensate for their project’s biodiversity impacts. It is seen as the last step in the mitigation hierarchy and a useful discipline to establish the optimum value of their projects.

Finding biodiversity units.

Where do you look for compensatory biodiversity? Your professional advisers may have some ideas. The local authority in whose area your site is located will advise you or have units to sell. If you know of a landowner, land agent, ecologist (Ecology by Design) or a land broker (such as Civity), you will get help. They will tell you where and how you can buy the biodiversity credits you need.

Biodiversity Credits.

These credits are the units of value for a registered parcel of land containing various types and conditions of habitat. However, the price you pay for each credit will vary considerably, dependent on factors such as:

  • The type of habitat required: ‘Broad’ (ie – grassland, wetland) and ‘Specific’ (ie -orchards, reedbeds). Every type of habitat has a notional value.
  • The rarity or richness of the species living there.
  • The physical condition of the habitat.
  • The distance between the location of the habitat and your site; The value decreases with distance (Spatial Risk Multiplier).
  • The seller: are you prepared to pay the offer price?

The government has introduced its own price guide called Statutory Credits. These are very much a last resort and nearly always cost double the stated values because of the Spatial Risk Multiplier. However, straight financial compensation is sometimes acceptable to LPAs who use the money to fund ecology projects of their own.

Biodiversity Credits can be bought from landowners, land agents, land banks (such as Civity) local authorities and, if all else fails, the government.

Responsible bodies.

You will know that the grant of planning permission is usually a matter for the LPA. However, a consultee may be a Responsible Bodieswhich consists of an assembly of individuals and/or corporate establishments. When submitting to a Responsible Body, you should take into account that their views may be wider and more ecologically-based than the LPA by virtue of its constituent members. This may influence the focus and style of your BNG plan application.

Start sooner than later.

 Assuming you have a site that you plan to develop at some stage, start the BNG process sooner rather than later. The LPA approval process is not quick, your application will go thorough several stages of diligent checks (ecological, legal, local, conservation covenants and national planning). Once the LPA approved your BNG plan in principle, you must secure the biodiversity credits, show how the habitat will be managed for 30 years (in some circumstances, Civity will assume the task). When you and your advisors are satisfied your plan is complete, submit it for final approval.


Now you know what is involved, make sure you allow enough time for you to initiate the searches, assemble all the data, put forward the application and get it approved BEFORE you seek planning permission.

Help is at hand

As we said, the process involved in getting approval for a BNG plan is dependent on so many factors – geography, ecology, opportunity – the best way to understand what you need to do is talk to us. We will listen to you and tailor-make suggestions how you start your BNG plan. There is no obligation. In the first instance, email for an appointment. We will respond immediately.

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