news article

Biodiversity Net Gain launch date confirmed

22 Jan 2024 | Technical News

Defra has confirmed the launch date for biodiversity net gain (BNG) as 12 February 2024. This means that, unless exempt, major developments will be subject to BNG from this date and small sites will be subject to BNG from 2 April 2024.

Major developments are defined as residential developments with 10 or more dwellings, or where the site area is greater than 0.5 hectares.

Small sites are defined for the purpose of the BNG exemption as:

(i) For residential: where the number of dwellings to be provided is between one and nine inclusive on a site having an area of less than one hectare, or where the number of dwellings to be provided is not known, a site area of less than 0.5 hectares.

(ii) For non-residential: where the floor space to be created is less than 1,000 square metres OR where the site area is less than one hectare.

BNG will only apply to new applications for planning permission for major developments made after 12 February 2024.

BNG explained by the Association 

Biodiversity Net Gain (BNG) will mandate the assessment of habitats on land that is due to be developed in England, and require this habitat to be enhanced so that it is in a better state than before the development.

Under mandatory BNG, all developments in England must replace any biodiversity lost and add a minimum of 10% biodiversity to provide a net gain. The resulting habitat will be secured for at least 30 years via planning obligations or conservation covenants, enforced by s106 agreements.

The scheme, introduced as part of the Environment Act 2021, will amend the Town & Country Planning Act and apply to new housing, infrastructure and commercial developments of all sizes. 

Habitat assessment by biodiversity metric

Underpinning mandatory BNG is a method of assessing habitats called the biodiversity metric. This biodiversity accounting tool is based on a Microsoft Excel document and will calculate how a proposed development will change the biodiversity value of an area of land, as well as the amount of ‘gain’ required. The tool is designed to provide stakeholders with a means of assessing changes in biodiversity value (losses or gains) brought about by development or changes in land management.

Habitat surveys and use of the biodiversity metric will be undertaken by competent persons (likely ecological consultants) working on behalf of developers, before being submitted as part of a planning application and scrutinised by specialists, including ecologists and planners, working within local planning authorities.

The currency of BNG: units and credits

The biodiversity metric tool will calculate the ecological cost of development on an area of land and generate a number which the developer must compensate for. This compensation currency is called a ‘unit’.

The number of units generated by the biodiversity metric for any given development depends on various factors including:

  • Distinctiveness: the type of habitat and its features, including species richness, rarity, whether the habitat is protected and the degree to which a habitat supports species rarely found in other habitats
  • Condition: variation amongst the same habitat type

There are three types of biodiversity units: area units, hedgerow units and watercourse units. For example, on one site there may be a total of 15.5 biodiversity units, which are comprised of 5.5 units of scrub, 8 of grassland and 2 of woodland.

The long-term goal: biodiversity gain plan

Once assessed using the biodiversity metric tool, a biodiversity gain plan will outline how a development will deliver biodiversity net gain and allow the planning authority to check whether the proposals meet the biodiversity gain objective.

Topics covered by the biodiversity gain plan include:

  • How adverse impacts on habitats have been minimised
  • The pre-development biodiversity value of the onsite habitat
  • The post-development biodiversity value of the onsite habitat
  • The biodiversity value of any offsite habitat provided in relation to the development
  • Any statutory biodiversity credits purchased
  • Any further requirements as set out in secondary legislation

The full biodiversity gain plan will be submitted either with the planning application or after the permission is granted, but before development has commenced.

What habitats will be created?

Local planning authorities have the option of setting priorities (for example, woodland creation or enhancing ecological networks) for biodiversity within their administrative area, which may be identified in collaboration with local wildlife organisations and stakeholders. These priorities will be formalised in local plans and planning decisions.

Therefore, in most cases developers will be given guidance on what form their biodiversity contribution should take. Pre-development assessments will also identify higher value or even irreplaceable habitats already on-site, which will be protected under best practice.

Where will habitat creation take place?

Best practice guidance dictates net gains should be delivered locally to the development site. In addition, a ‘spatial risk multiplier’ attached to the biodiversity metric tool will incentivise developers to undertake biodiversity improvements within the boundary of a development (on-site), by reducing the biodiversity value of habitats delivered further away from the development.

Where on-site improvements are not possible (for example where there is not space on site for the development and habitat areas) improvements can be made off-site. The term ‘off-site’ in the context of BNG may mean on land owned by the developer, which is away from the development site, or alternatively by purchasing units sold by third-party land managers who are already in the process of creating new habitats throughout the UK.

Estimates using 2019 housing delivery data suggest on-site and off-site habitat creation will demand a total of 5,400 hectares of land each year in England.

Trading BNG units

The development of a third-party BNG unit marketplace was an intended consequence of the BNG scheme, and numerous businesses already offer units for sale throughout the country (type ‘BNG units for sale’ into Google for examples).

Off-site units being sold by third parties generally form part of large, privately managed habitat restoration projects, ranging from grasslands to re-wilding and re-wetting projects. Thousands of units are already available for purchase, which is just as well, since Defra estimate 1,300 ha of off-site units will be sought each year by developers.

The cost of each unit being sold by third-party providers will include management of the land for at least 30 years, monitoring and reporting, ecologist or other experts’ costs, insurance, costs to cover work if the habitat fails, machinery, tools and other staff to carry out the tasks, inflation and market competition costs and the cost of legal administration. Defra estimate the cost for each unit is likely to be in the region of £9,000 - £15,000, however, due to the immature nature of the market, this figure may vary. Crucially for developers, once they purchase BNG units from third parties, they absolve themselves of all liability for BNG mitigation.

Developers who cannot use on-site or off-site units to deliver BNG must purchase ‘statutory credits’ (note the difference in terminology between units and credits) from the government. This option is regarded as a last resort and priced accordingly high; statutory credit prices are set to ensure they do not compete with the development of units for sale by third parties. The proceeds from the sale of ‘statutory credits’ will go towards government-led conservation projects.

The biodiversity metric tool is currently being developed so that when BNG becomes mandatory, developers who need statutory credits can work out how many they need, depending on their intended development.

In July 2023 the government announced indicative prices for statutory credits, starting at £42,000 per credit for more common habitats, up to £650,000 for rare habitats. 

Will BNG benefit the landscape community?

BNG is one of many government initiatives purported to increase the number of ‘green jobs’ and has the potential to benefit every member of the landscape and wider environmental community, from ecologists to designers, suppliers to contractors.

The potential benefits to the landscape and environmental industries are likely to arise from various aspects of work throughout the BNG process:

  • Assessment of development site (pre-development): provision of ecological services for an assessment of the site and delivery of biodiversity gain plan
  • Design of habitats for developers, either as part of on-site projects or off-site projects, as part of biodiversity gain plan
  • Design of habitats for third-party land owners looking to sell units to developers
  • Creation of habitat as described in biodiversity gain plan: the creation of habitats using materials, products and skilled labour
  • Creation of habitats for third-party land owners, using materials, products and skilled labour
  • Monitoring of sites: provision of regular monitoring services of the site by competent persons. Subject to agreement, may be undertaken during maintenance of site by operatives
  • Maintenance of site: regular, skilled maintenance of all living aspects including replacement of failed specimens and damaged products

Aside from the obvious need to enhance and create a wide range of high-quality new habitats on sites of all sizes and locations, habitats created under the BNG scheme must be secured for a minimum of 30 years.

Given the intended life expectancy of projects and the level of scrutiny they will face by the local planning authority and interest groups, it is likely regular, skilled assessment and maintenance will be in demand throughout England. Landscape professionals of all disciplines should benefit from the demand for skilled maintenance work on sites, either on developer-led sites or off-site for private enterprises.

Will BNG benefit the environment?

Historically, the success of global biodiversity compensation schemes has been mixed. Ensuring proposed compensatory ecological gains materialise, and last for the duration of the harms they are meant to compensate for, has been a key challenge.

All off-setting schemes risk incentivising developers to minimise their costs by underestimating the biodiversity impacts or seeking the least costly forms of compensation. Developers and project proponents are also often better resourced than statutory agencies tasked with regulating the system.

Peer-reviewed research into the likely success of mandatory BNG used information collected from major developments across six ‘early adopter’ councils, who started implementing policies equivalent to BNG in advance of the mandatory introduction.

Research findings suggest the flexibility of the system which allows developers to meet their BNG obligations, together with the quality and consistency of governance overseeing the projects, is a determining factor in whether the environment and the landscape industry will benefit from mandatory BNG.

The BNG metric requires inputs based on judgements of ecological consultants working for developers, and is particularly sensitive to habitat type, distinctiveness, and condition score. To avoid sites being undervalued, sufficient information must be provided in BNG assessments to ensure ecologists working for local authorities can scrutinise them. To help, earlier this year the government announced £15.76m has been committed to help local authorities recruit additional ecologists and specialists necessary to audit BNG applications.

The Government is encouraging on-site biodiversity improvements above off-site areas or the purchase of units from third parties. Researchers suggest this approach should be subject to councils being suitably staffed to monitor compliance. Currently, the reactive nature of English planning enforcement is poorly suited to guaranteeing the delivery of high-quality habitats, and research suggests compliance with on-site habitat mitigation and compensation measures in the UK is currently low.

The BNG system proposed in the UK will trade biodiversity losses today for uncertain future gains. Promises of future biodiversity gains represents a risk, since compensation measures are only of value if mitigation projects are implemented as per proposals and maintained appropriately. Poor projects have the potential to undermine biodiversity benefits.

Research into early BNG schemes revealed the overall area of green space within developments declined, despite a 20% increase in biodiversity. The overall decline in greenspace area isn’t necessarily bad news, as the loss will be mitigated by habitats of higher distinctiveness and condition in the future, which should increase ecological resources available to wildlife.

Huge potential for the environment – and the industry

The most reliable mechanism for reducing the impact of development on biodiversity is to redirect development to previously degraded sites. This approach isn’t always possible, which means some degree of impact will result from development.

However, the current rate of loss is unsustainable, due to biodiversity being undervalued either during initial site assessment or when mitigating the effects of development.

The landscape industry is frequently called upon to replace greenspaces and habitats destroyed by construction and infrastructure projects, but members will be aware the landscape and wider environmental industry is also undervalued, with adequate funds for successful schemes rarely allocated. Members will be familiar with that feeling of frustration upon seeing badly executed landscape elements: poorly staked or planted trees, use of damaged specimens, poor quality materials or workmanship. Members will also be familiar with the barriers to the success of landscape elements: over-zealous value engineering and unrealistic maintenance budgets.

BNG represents a good step towards mitigating land lost to development of all sizes and has the potential to conserve and improve the overall quality of important habitats. The creation of work which utilises the broad range of skills offered by the landscape industry should also be celebrated.

The Association hopes BNG will provide statutory agencies with the teeth to police non-conformance, and the industry with realistic budgets to create and maintain sites.

Further reading

Defra article: BNG launch date confirmed

back to 'news results'