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What do the new Biodiversity Net Gain requirements mean for schools and colleges?

In England, the Biodiversity Net Gain (BNG) regulatory framework came into effect on 12 February 2024. This means there is a mandatory legal requirement for most planning applications to provide a 10% increase in biodiversity. This represents a fundamental change to the planning system and seeks to ensure habitats for wildlife are improved through development. 

This article from the Irwin Mitchell Environment Law Team seeks to provide an overview of what to consider if you are looking to (1) develop new buildings on previously undeveloped land or (2) redevelop parts of your estate. 

For the purposes of the BNG requirements, all land is scored based on its variety and type of biodiversity against a metric which provides how many ‘biodiversity units’ the site totals. This new legislation therefore seeks to increase that value post-development. 

The BNG should ideally be provided onsite (within the red line boundary of the development site). However, if this is not possible it can be provided partially or wholly offsite and, if this still isn’t possible, statutory credits can be purchased as a last resort (these are intentionally highly priced, and the revenue is used for investment in habitat creation). 

The BNG will need to be secured for a minimum of 30 years and failures to do so can be enforced against by the appropriate authority. A legal agreement or covenant will be entered prior to permission for development being granted to secure the net gain for the required time.

It should also be noted some local planning authorities require a net gain of greater than 10%. 

New development 

If proposing new buildings on previously undeveloped land, it is highly likely BNG will need to be provided. 

The requirement to provide BNG already applies to “major development” but does not yet apply to small developments. However, small developments are only exempt until 2 April 2024 (small developments include those of less than 1,000 sq. m or on a site area of less than 1 hectare). 

This differentiation will still be relevant post-2 April as a different calculation metric is used for each. If you are proposing development on previously undeveloped land, it is recommended you take advice early so you can decipher whether the development is considered major or small and therefore which biodiversity metric will need to be applied.  

As set out above, BNG should ideally be provided onsite. This can provide great opportunities for education on ecology; however, this obviously will not always be a viable option due to space restraints. Regardless of where the BNG is going to be provided, a legal agreement or covenant will need to be entered with the relevant authority. 


It is very worth noting that there are some exemptions to having to provide BNG and this includes the de minimis exemption. If development is below the following thresholds, BNG does not have to be provided:

  • The development does not impact a priority habitat (as defined in the Natural Environment and Rural Communities Act 2006); and 
  • If there is an onsite impact, it impacts less than 25 sq.m of onsite habitat and 5m of onsite linear habitats (e.g. hedgerows). 

For the purposes of the BNG requirements, an “impact” means a decrease in biodiversity value. 

Examples of development which may fall within this exemption include:

  • Development on an existing car park, if the car park is a sealed surface with a biodiversity value of zero. 
  • Demolition of an old teaching block to replace with a new teaching space, as the existing block would be classified as developed land and have a sealed surface and likely a biodiversity value of zero. 
  • Extension of a building (less than 25 sq.m) onto a grass playing field, as although the grass would have a biodiversity value, the size of the habitat lost would be less than 25 sq. m. 
  • Change of use of an accommodation building into teaching space, as the development would not require use of further land. 

However, it is always worth seeking advice before relying on this exemption as evidence will need to be provided with the planning application as to why the exemption applies. 

If you’d like to speak to the Irwin Mitchell Environment Law team to discuss any of the above further, please do get in touch.