News & Insights

The journey towards mandatory biodiversity net gain


Biodiversity Net Gain (BNG) is widely described as ‘development which leaves biodiversity in a better state than before’. But is this a helpful definition, and how does BNG fit with wider changes in the planning system? In this article, written by Ecology Associate Jamie Woollam, we discuss where we are on the BNG journey and what the future holds.

2 years-on

At the time of writing, development professionals remain in BNG-limbo. Back in 2019, the Environment Bill was tabled by Teresa May’s government, a new biodiversity metric was issued for beta-testing (BM2.0) and there seemed to be momentum towards mandatory BNG in the English planning system. Nearly 2 years on, notwithstanding a general election, Brexit-day, international pandemic, the planning white paper and recent local elections, it could be argued we are not much further along the BNG path. At least on the face of it.

A handful of Local Authorities have proceeded to include BNG policies within their local plans, some specifying the use of particular metrics, others setting their target % gain (ahead of the Environment Bill). Even in the absence of local policy, BNG is now regularly raised in consultations and planning committees across the country, with the application of the NPPF3 (namely paragraph 170(d)) being the principal justification. In Milton Keynes we have an inspector’s decision on local BNG policy- helpfully confirming, that in the absence of statute, policy indicates a minimum gain of 0% i.e. no net loss of biodiversity.

In these 2 years we have learnt a lot about how BNG can change scheme design and how to plan for development, particularly in strategic land. No longer an afterthought, BNG considerations are often now driving early thinking when it comes to land deals: can, or should, BNG be delivered on-site or offset nearby, what will be the affect be on capacity/housing numbers, what are the likely costs. This significant commercial interest is forcing developers and planners to better understand aspects of the process that would previously have been the realm of ecologists alone: the ‘science’ of habitat survey and assessment, and the ‘art’ of habitat restoration and creation.

The challenge of retrospectively applying BNG principals to housing allocations has also become clear. BNG is largely unaccounted for within housing numbers, with questions of ecology left to development control policies, and therefore the application of the mitigation hierarchy is skewed towards off-site compensation. Whilst such off-site biodiversity provision can deliver strategic benefits, it’s also clear that we need to be thinking about the separation of people from accessible natural greenspace. This is particularly true in a post-Covid era, with access to nature for our physical and mental wellbeing high on the agenda.

Best estimates remain that the Environment Bill, with its associated BNG provision, will become law late in 2021. A standard planning condition will be applied to most consents in England to meet the ‘Biodiversity Gain Objective’. Assuming a 2-year transition period, as muted, this suggests we will have until late-2023 to fully prepare for mandatory 10% BNG. For strategic land, and much immediate land, 2 years in the planning world is a blink of the eye – particularly if we assume one of those years is needed to collect suitable baseline habitat data.

What (we think) we know about BM3.0

As we wait for the third iteration of the Biodiversity Metric to be published by Natural England, scheduled for publication around 7th July 2021, some updates are trickling through. In lieu of full publication, several recent presentations by Natural England have indicated the direction of travel:

• Built-in rewards for creating habitat in advance. A boon for habitat banking?
• Conversely, penalties for deferring habitat creation. Earlier provision of open space and habitats within development sites?
• ‘Suburban mosaic’ habitat will be replaced with guidance on development parcels: 70/30 split between developed land and gardens. A welcome standard to avoid disputes at the outline application stage.
• Revised values for some habitats. Will the metric closer reflect perceived or scientific biodiversity value?
• Removal of some calculation variables, including ecological connectivity and accelerated succession. This should reduce variation in metric outcomes.
• Condition Assessment, a fundamental part of any baseline assessment, will be revised and improved following industry responses.

The Biodiversity Metric 3.0 (BM3.0) is assumed to be THE metric adopted by the Secretary of State under Schedule 14 of the Environment Bill 2019-2021 (inserted Schedule 7A to the Town & Country Planning Act 1990). As such, the above changes could have significant impacts on how to account for, and design in, BNG in new developments in England.

The Industry Challenge

Developers will be familiar with those “pesky newts, holding up development”. Indeed, the ecological-industry has grown significantly on the ‘bread and butter’ of legally protected species, typically newts and bats. However, BNG metrics focus almost entirely on fundamental aspects of ecology: flora, vegetation and habitat.

A challenge for the ecological industry therefore is to upskill a workforce of newt-counters (no insult intended), to the detailed botanical work required for robust BNG accounting, not least in the minefield of habitat condition assessment. Not every project requires a bat-surveyor, but (almost) every project will need a good botanist.

For those instructing habitat surveys, how will they know they can have confidence in the survey work they are paying for? Particularly if one increment change in habitat condition can dramatically affect a comfortable +10% BNG position, with all the financial ramifications. The only current industry standard to help determine botanical skills comes from the Botanical Societies of the British Isles’ (BSBI) Field Identification Skills Certificate (FISC): those demonstrating level 4 or above should be able to collect the quality of habitat data required.

But FISC is not the end of the story. The forensic nature of biodiversity accounting and metrics, as well as the understanding of development design and land-use change, creates a challenge for even the best botanists.

The Environment Bill places planning authorities firmly as the gatekeeper for approving BNG submissions. They must approve a ‘Biodiversity Gain Plan’ only if satisfied with the information present and that the BNG objective is met. This will require equal or greater expertise within the authority to approve the plans.

The sheer volume of BNG assessments likely to be required in England will require the whole industry, and their LPA counterparts, to get their collective act together. And there’s potentially less than two ‘survey seasons’ to go.

Building Better, Building Beautiful, Building Biodiversity?

With the government’s aspiration to “promote and increase the use of high-quality design for new build homes and neighbourhoods”, BNG is a strong contender for delivering some substantial improvements in both the setting and quality of development. However, nature is rough around the edges, and there remains a disconnect, both in urban and rural minds, between how nature is portrayed, and what the English-landscape wills to be. In practice, there are some obvious options to deliver both beautiful and biodiverse landscaping:

Wildlife Ponds– very little competes with open water for biodiversity value on a small scale, with equal benefits for well-being,
Community Orchards– equally, traditional orchards, with local varieties and wildflower beneath, deliver significant biodiversity value, and serve as a point of interest and community benefit.
More trees– tree lined streets, parkland trees and in drainage features. On development sites, native tree-planting (rather than natural regeneration, the better option for large scale off-site) should always factor into landscaping for biodiversity and well-being.
Grassland– whilst not always the solution given the work required to deliver and maintain it, wildflower grassland remain one of the mainstays of habitat creation on development sites. Get the conditions right (low nutrient) and these grasslands will be cheaper to manage and provide a welcome contrast to the amenity lawn.

For the wider landscape, ‘rewilding’ is touted as the solution to the biodiversity crisis, but ‘Regenerative Agriculture’ is likely the more palatable, and ultimately deliverable, path. We could view BNG on-site in a similar way: ‘Regenerative development’ to reconnect people with what nature feels, smells and looks like. Development which also rejuvenates minds and gives us space to grow. A laudable aim for a planning condition.

CSA Approach

At CSA our teams bring together the key skillsets to get your BNG assessment and design right:

Ecologists across the country, including FISC level 4 botanists, to establish a robust habitat baseline and explore the BNG options both on- and off-site
Urban Designers, to masterplan your scheme with efficiently, building better and beautiful
Landscape Architects, designing your open spaces to balance biodiversity and recreational needs