Biodiversity net gain (BNG) – guidance for developers

Biodiversity net gain is a national policy requirement, designed to ensure that new developments have a positive impact on local nature and biodiversity.

Overview

Biodiversity net gain (BNG) is a national policy requirement, designed to ensure that new developments have a positive impact on local nature and biodiversity.

Developers in Hammersmith & Fulham must deliver a BNG of at least 10%. This is in line with the national minimum target and part of the action the council is taking to tackle the climate and ecological emergency.

This requirement applies to major schemes from 12 February 2024 and minor schemes from 2 April 2024.

Developers can find guidance and resources here on this page.

For further information and questions, email BNG@lbhf.gov.uk

What is biodiversity net gain?

BNG helps increase the quality and quantity of natural spaces for the benefit of both wildlife and people. It requires developments to leave biodiversity in a measurably better state than it was before the development takes place.

The Government has made it a mandatory requirement for developments to achieve a minimum 10% BNG through the Environment Act 2021. This is aligned with H&F's target as outlined in H&F's Climate Change Supplementary Planning Document (SPD).

To achieve BNG, developers must follow the mitigation hierarchy of 'avoid, mitigate and compensate'.

This means that avoiding impacts on biodiversity is the priority and this is reflected in the assessment of BNG through the DEFRA metric. The improvements to biodiversity and associated habitats must be monitored and maintained for a minimum of 30 years.

Find out more about BNG (GOV.UK).

Do I need to comply with BNG?

All major developments are required to be BNG-compliant from the 12 February 2024. This applies for applications submitted from this date.

Major developments include those which either:

  • provide 10 or more dwellings, or
  • include 1,000m2 or more of non-residential floorspace.

A mandatory BNG for minor developments will apply for applications submitted from 2 April 2024.

Householder applications are not covered by the BNG target but are encouraged to include measures to increase biodiversity.

Check government guidance for developers (GOV.UK).

Exemptions include:

  • development with no impact on priority habitat and where impacts fall below the specified 'de minimis' threshold, including site area of less than 25m2, or 5m long for linear habitats such as hedgerows and rivers
  • householder applications
  • the high-speed railway network
  • off-site gain developments, where habitats are being enhanced for wildlife
  • certain self-build and custom build developments.

Check if your development is exempt from BNG (GOV.UK).

If your development is exempt from BNG, we still encourage species and habitat enhancements to be incorporated, to help tackle the ecological emergency and provide more opportunities for our wildlife.

This can include new native planting and habitat features such as log piles. Guidance on how to do this is contained in the council's Climate Change SPD.

How to complete a BNG assessment

BNG must be measured using the most up-to-date DEFRA statutory biodiversity metric. This metric is intended to be used by a suitably qualified ecologist.

The ecologist will need to conduct a site visit to classify and measure the habitats existing onsite and then assess the development site plans and landscaping. They will be able to provide advice on what should be retained, enhanced and created. It is therefore important that ecologists are brought into the design stage early.

Further details about the biodiversity metric (GOV.UK).

How to achieve BNG

Developers should prioritise retaining any valuable habitats before considering enhancing or creating habitats to achieve BNG. Where habitats are not valuable (such as sealed surfaces), or BNG is not met, developers must create and enhance habitats on-site to meet their BNG target.

If you are struggling to meet the target 10%, the following design considerations could have an impact:

  • retaining more of the original habitat
  • retaining more trees
  • new trees and other planting consisting of native species
  • replacing planned 'low value' habitats such as non-native ornamental planting with 'high value' habitats, such as a wildflower meadow, mixed native shrubs or a pond.

Read about how to make on-site biodiversity gains as a developer (GOV.UK).

What if BNG cannot be achieved on-site?

It should first be considered whether changes to the site plan can increase the BNG score.

Should it be clearly demonstrated that meaningful on-site BNG cannot be achieved, off-site opportunities can be pursued. Applicants should aim to implement off-site BNG as local as possible, with preference to staying within borough boundaries.

As a final resort, the applicant can look into buying statutory BNG credits from the government.

Read about how to make off-site biodiversity gains as a developer (GOV.UK).

What needs to be submitted with a planning application?

If a proposed development is believed to be subject to the biodiversity gain condition, the application must be accompanied by the minimum information below. This allows us to determine whether your proposal will reach the minimum BNG target.

The application must be accompanied by:

  • confirmation that the applicant believes that the development would be subject to the biodiversity gain condition
  • the pre-development biodiversity value(s) and a statement whether activities have been carried out prior to the date of application that result in loss of onsite biodiversity value, and where they have:
    - a statement to the effect that these activities have been carried out
    - the date immediately before these activities were carried out
    - the pre-development biodiversity value of the onsite habitat on this date
    - the completed metric calculation tool showing the calculations, and
    - any available supporting evidence of this
  • a completed and valid metric spreadsheet in Excel form (a summary will not suffice)
  • a plan (GIS shapefile) of the site boundary
  • plans (GIS shapefiles) of existing and proposed habitats
  • a description of any irreplaceable habitat.

Further information is also required, but can be provided either at full application stage (preferable) or post-planning approval if permission is granted. This includes:

Where applicants consider that the development would not be subject to the biodiversity gain condition, Article 7 of The Town and Country Planning (Development Management Procedure) (England) Order 2015 provides that the applicant must provide a statement as part of the planning application setting out the reasons why they believe this is the case.

What happens after planning permission has been granted?

Planning permissions will include a condition requiring developers to submit a detailed biodiversity gain plan to the council for approval. This should be submitted after the council approves the planning application, and ahead of the development works.

A biodiversity gain plan shows how a development will achieve BNG and must include:

  • a completed metric calculation tool
  • pre-development and post-development plans (showing the location of on-site habitat)
  • a compensation plan if the development impacts irreplaceable habitats
  • BNG register reference numbers if off-site units are included as part of the plan
  • proof of purchase if statutory biodiversity credits are required as part of the plan
  • a habitat management and monitoring plan (HMMP) - HMMP guidance (GOV.UK).

Download a biodiversity gain plan template (GOV.UK).

Further advice

For further information and questions, email BNG@lbhf.gov.uk

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