Find your way through the biodiversity net gain maze
As Biodiversity Net Gain legislation passes its first birthday, Anna Highfield looks at how architects are finding the new rules and asks whether Labour is as committed to nature recovery as the Tories.
It all sounds so simple, so commendable. When you build something new, you must make sure there is more natural habitat on the site – ‘measurably better’, as the legislation puts it – than before the contractors’ shovels went into the ground.
But the seeds of good ideas take time to blossom, and the first year of the Biodiversity Net Gain (BNG) regime has not been without its hiccups. One report in The Telegraph even claimed the new biodiversity drive was ‘killing developments and destroying affordable housing schemes’.
Introduced for major developments on 12 February 2024 and for smaller developments two months later, BNG mandates that all new developments, except a ‘narrow’ exemption list, deliver at least 110 per cent of a site’s pre-existing biodiversity.
Dubbed ‘the biggest change to planning regulations in decades’ by the Conservative government at the time, the law, embedded in the Environment Act, promised to help reverse a ‘devastating decline’ in UK species, which have plummeted 19 per cent in their abundance since the 1970s. It recognised, for the first time, the value of all English wildlife habitats within the planning system.
In practice, a site’s biodiversity value, both before and after development, is measured in ‘biodiversity units’ by an ecologist using a standardised metric. Developers must then guarantee a 10 per cent increase on this value, via a ‘mitigation hierarchy’ of biodiversity delivery options.
‘Clients will often ask for the cheapest option without accounting for the full-on, ongoing maintenance regime’
The most preferred is an on-site uplift – for example by incorporating wildflower meadows, hedgerows, bat boxes, or ponds and wetlands into a scheme’s landscaping – followed by off-site gain, which secures like-for-like biodiversity units from a landowner. As a ‘last resort’, developers can buy biodiversity ‘statutory credits’ from Natural England. Crucially, developers must maintain the uplift for 30 years.
The nation’s BNG drive has been hailed by Oxford University biologist Natalie Duffus as ‘one of the most ambitious schemes’ the world has seen, with other nations watching keenly to see how it unfolds.
The legislation is complex and still evolving but the industry is rapidly wising up to both the benefits and snags of BNG. So how is the law faring?
Like any new legislation, BNG has suffered teething problems in its first 12 months.
As the industry scrambled to respond to the new law, environmental consultants were inundated. Nora von Xylander, biodiversity and sustainability specialist at Tunley Environmental consultancy, says the ‘stressful’ first year has been mired in delays and frustrations as clients raced to adapt or re-submit plans to meet BNG requirements. She says the message from development teams has been: ‘We needed this yesterday’.
But von Xylander says architects are now ‘looking at BNG from the start, rather than tracing it backwards’ – and clients are becoming ‘more and more receptive’ by the month.
Architects might be ahead of the game, but the BNG planning panic has had an industry-wide ripple effect – and not all for the good.
An AJ expert source, who wishes to remain anonymous, says BNG has led to a ‘cowboy market’ as developers flounder for information and opportunists jump into the skills vacuum.
The source cites developers ‘literally bending rules to get through’, local planning authorities ‘taking payments for BNG when [the authority] hasn’t got a way of delivering it’, ecologists writing ‘blatantly false’ biodiversity plans and habitat bank operators offering ‘ridiculous’ off-site solutions ‘purely for commercial gain’.
Amid the ruckus, those organisations with genuine expertise in BNG are highly sought-after.