Building with Nature:

Why Biodiversity Net Gain is Essential for Your New Project

Ruth Marshall

You  may have heard of Biodiversity Net Gain, and if you are planning a new build then you certainly will soon! Here Ruth Marshall, CEO of CGLA, the award-winning Landscape Design and Construction company briefly covers what this means for those considering a new development.

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What this is..

Put simply, it is now a legal obligation for all new developments in England to demonstrate how their development will deliver a calculated net 10% improvement in biodiversity over a 30 year period. The law already applies to larger developments, and smaller ones are covered from April 4th 2024. Whilst there are some exceptions, (typically most extensions, tiny developments and self-builds), you should assume any new build is covered and definitely check exemption if you think this to be the case.

The goal of the legislation is to set out a process that guides those planning a development into making decisions that are measurably better for our biodiversity as a whole. This adds to previous protection measures, so does not replace them, and is much more sweeping. You will not obtain planning permission without a specific and detailed plan to achieve this!

What will I have to do?

You will need to start with a “baseline assessment” which analyses the nature and quality of the different habitats present on the site including existing buildings if present. Available records for your site and immediate surroundings that identify protected habitats are also researched to provide important site context. The data is fed into a complex spreadsheet that delivers a baseline metric.

Your proposed building plans are then also fed in to the modelling, and the net difference (in most cases a reduction,) in the biodiversity ‘score’ is calculated. This then sets the target- you will need to explore ways in which you can not only offset any reduction, but also improve the overall score by 10% (ie a Biodiversity Net Gain of 10%).

You are expected to aim to do this within the landscape plans for your own site, although where this simply is not possible there are some paid offset mechanisms to effectively pay for the Net Gain to be achieved offsite.

Once you have developed a plan that delivers this BNG You will then submit the plans which will be a legal requirement of the planning process. The local authority is required to keep a register of these plans and these are required to be sustained for 30 years.

How does it benefit me?

This may feel like an onerous requirement but aside from the overall ecological arguments, which others are much better qualified than me to describe, (do explore EMEC Ecology for more detail), there are some significant practical benefits to this approach.

Many people planning a new build are focussed on the building rather than the development of the plot as a whole, and this does miss a trick in terms of a holistic approach to the design. Good overall design will maximise not only the internal spaces, but how they relate to the garden or landscape beyond, and the dressing of the house to sit well within its surroundings.

You don’t need a BNG assessment to do this, but having to do one will force some of these decisions to be made earlier which is typically better for aesthetics, practicality and cost, as well as achieving the environmental goals that most of us aspire to but perhaps need some nudging to deliver on.

How do I do this?

You can do this yourself- the metric spreadsheet is available from the Government Website although this is really not for the faint-hearted, and the Local Authority does require a ‘Competent person’ to have carried out the assessment. They have not defined this but one assumes there is a risk in carrying it out yourself if this falls outside of your experience. Most people will probably want a suitable third party to take this on. The preliminary assessment is however only the first part of the task.

However you choose to do this, the BNG becomes an important discussion point for you in planning the overall layout of your site, so getting from the initial assessment to the final plan is likely to be a 3-way effort between yourselves, your landscape designers and your architects as to how you optimise achieving your legal obligations.

How can CGLA help? (and do I need an Ecologist?)

We value the expertise and skill that goes into an Ecology report, and one may be a requirement from the Local Authority as part of a broader planning application (bats and badgers for example!). It is not however a requirement to employ one for BNG assessments on the majority of smaller and more straightforward sites. On larger or more sensitive sites we can arrange for an ecologist if required, and allow them to focus their time and skill on the parts that need it, not the fiendish spreadsheets!

The initial site assessment is only one part of the BNG regulations however. You will also need a detailed plan demonstrating exactly how you will deliver the required uplift in the biodiversity metric. A landscaping plan is the essential core part of this.

The CGLA team have been delivering award-winning landscape designs for 25 years. The BNG regulations can be smoothly addressed within our design process, and addressing them fits well into our normal stages of works, although typically the landscape design will need to be considered earlier than has been the norm- preferably at Pre-Application stage of planning.

Whilst this is early days of new legislation, we at CGLA have already completed several BNG assessments and calculations. We are now using tools and resources developed by a team of professionals who have been working closely with DEFRA for the 3 years in the run up to the legislation going live. We will be delighted to share how our process might work for your project.

The CGLA team can typically include the Initial Assessment and BNG calculations as an integrated part of our Landscape design package, making the Biodiversity Assessment and plan development a smooth and integrated process within the context of your overall site requirements.

Do get in touch with us to discuss any aspect of your build or feel free to put us in touch with your architects to see how we can make this a seamless process for you.

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CGLA are an award winning team of Garden Designers, Landscape Architects, Landscapers and Garden Maintenance Operatives working in Buckinghamshire, London and the South East, as well as on prestigious design projects across the UK and abroad. We are currently working in Oman, Jersey and France, and welcome enquires for design, landscaping or garden maintenance. Contact us here