The Promise of Biodiversity Net Gain
Growth, housing, and the myth that nature is holding us back
Biodiversity Net Gain or BNG, for those of us who spend our lives acronyms-deep, is not a grand rewilding vision or a utopian promise.
It is a practical response to a very British problem: we build things, we damage nature, and then we are surprised when nature disappears.
BNG was introduced because we had reached the point where asking developers to be nice was clearly not working.
For decades, development in England has chipped away at habitats. Hedgerows torn out, ponds filled in, and meadows reduced to lawns. The planning system acknowledged harm, but rarely required anything meaningful in return.
Meanwhile, public funding for nature recovery shrank and shrank, while expectations of what nature should deliver like flood protection, clean water, carbon storage, beauty, and wellbeing, expanded.
BNG was meant to help close that gap.
It became mandatory in England in early 2024, requiring most developments to deliver at least a 10% measurable uplift in biodiversity, secured for 30 years.
The idea was simple enough to explain over a cup of tea: if development causes ecological harm, then development should also help pay to fix it. Not by planting a token tree in a car park, but by funding measurable, long-term habitat creation and restoration elsewhere.
Private money for a public good.
A new lever in a system that desperately needed one.
BNG has been live for less than two years. In ecological terms, two years is nothing. It’s barely long enough for a hedge to notice it’s been planted.
The rules were still bedding in, local planning authorities were still learning, land managers were still weighing up whether this was worth the paperwork and patience it demanded.
The market was slow, but showed promise.
Then came the growth agenda.
Get Britain Building Again
Just as BNG was starting to find its feet, the government doubled down on development through the Planning and Infrastructure Bill and a series of consultations on what it called “streamlining” biodiversity requirements.
There’s now a explicit political focus on housing, with a headline target of building 1.5 million new homes within this Parliament. In other words, a timescale driven by elections.
Get Britain building again, we were told. A slogan eerily similar to Make America Great Again, a nod to right wing populism that trades in urgency over understanding. It reduces a complex, long-term challenge and turns it into something easy to chant and hard to question.
Housing has become the shorthand for growth. Speed has become the metric of success and anything perceived as slowing delivery is suddenly under suspicion.
That’s how nature, and mechanisms like BNG, became the scapegoat of a failing economy.
What’s Changed & Why it Matters
The government opened a major consultation in May 2025 on whether to roll back or reshape BNG for smaller sites.
They announced just before Christmas (timing, as ever, impeccable) the outcome.
Developments under 0.2 hectares, roughly the size of half a football pitch, are now exempt from BNG requirements. Ministers argue this would cut costs for builders and save time for local authorities.
Independent analysis suggests that sites of this size account for around 82% of all planning applications. This means that 4 out of 5 developments will now make no contribution to fixing nature at all.
Consultation is meant to be a pause. A chance to test, refine, and improve not undermine the very market it was designed to create.
Over the six months, the uncertainty has done what bulldozers could not.
Land managers hesitated. Investors stepped back. Local authorities, already overstretched, became understandably cautious. Deals stalled. Pipelines emptied. A market designed to unlock long-term nature recovery found itself frozen in short-term doubt.
Now the rules have changed and we’re left wondering what the game actually is.
Nature vs Development: The Myth That Nature Slows Everything Down
Developers argue that environmental requirements slow delivery. That if only we could loosen the rules, homes would magically appear.
But delays in housing are rarely caused by nature.
They are caused by land banking, skills shortages, infrastructure gaps, finance, and increasingly, a planning system trying to do too much with too little capacity.
Multiple reviews of housing delivery in England have found that permissions far outstrip completions, with hundreds of thousands of consented homes left unbuilt each year.
Nature is not what is holding things up.
What does move quickly, however, is the influence of those whose bottom line is most affected.
Developers are well-organised, well-resourced, and close to power. They have trade bodies, lobbying capacity, and direct lines into decision-makers.
Nature, by contrast, does not lobby. Rivers don’t write letters and lapwings do not attend roundtables.
That imbalance matters when policy is being reshaped at speed.
Organisations like the RSPB, National Trust, and The Wildlife Trusts made strong, evidence-based cases for keeping nature protections in place. They mobilised public support, briefed MPs, and rightly argued that weakening environmental safeguards would store up costs rather than remove them.
But it wasn’t enough.
An amendment to the Planning and Infrastructure Bill that would strengthen protections for England’s chalk streams (one of the rarest habitats in the world) was rejected by the House of Commons.
That moment was telling.
It revealed how easily nature is framed as the problem to be managed, rather than the foundation to be protected.
In doing so, it revived the tired myth that we must choose between building homes and protecting nature, which is a choice we don’t actually have to make.
Because elsewhere, we’ve already seen how building with nature can work.
Building With Nature (Not Around It)
Across the UK, initiatives led by The Wildlife Trusts and partners have spent years proving that development and nature are not sworn enemies.
Building with Nature sets clear, evidence-based standards for green infrastructure. Things like accessible green space, water management, and wildlife connectivity and certifies developments that meet them.
Likewise, The Wildlife Trust’s Biodiversity Benchmarking helps developers understand what good looks like early, embedding nature into design from the very beginning.
It shifts the conversation from how little can we get away with? to how do we design this well from the start? saving time, cost, and conflict while delivering places that function better for both people and nature.
These approaches don’t stop homes being built. They stop bad places being built.
That distinction matters.
It matters because the real question isn’t just how many homes we build, but where, and what kind of places we want to live in.
Places that flood?
Places that overheat?
Places without trees, birds, or space to breathe?
Or places that last.
That are climate resilient.
That are simply… nice to live in.
Elsewhere, We’ve Already Figured This Out
Internationally, this isn’t radical.
In the Netherlands, nature-inclusive design is embedded in housing policy.
This grew out of national policy shifts in the last decade to become nature positive, which recognised that housing delivery, climate adaptation, biodiversity recovery and human health are inseparable challenges, not competing ones.
Cities such as Amsterdam and Breda now use biodiversity point or scoring systems, where developments earn points for features like green roofs, rainwater management, wildlife corridors, nesting sites, and native planting. Meet the standard, and your scheme progresses. Miss it, and you redesign.
In parts of Germany, they recognise that urban development brings real risks: flooding from heavy rainfall, overheating during summer heatwaves, and the steady erosion of urban biodiversity.
Rather than treating these as separate problems, planning policy addresses them together and green roofs and urban habitat corridors are standard practice.
In Stuttgart, the city requires green roofs on most new buildings, with a strong focus on stormwater retention. Roofs are expected to hold back rainfall, reduce pressure on drainage systems, and cool buildings naturally in a city particularly vulnerable to heat stress due to its topography.
In Singapore, nature is layered vertically and horizontally into one of the densest cities on earth. Nature is treated as critical to cooling, flood management, biodiversity and everyday wellbeing.
This the result of a long-term national strategy, often described as the City in Nature vision, which recognises that in a hot, flood-prone, highly urbanised place, nature has a job to do. Greenery is expected to cool streets and buildings, manage intense rainfall, clean the air, support biodiversity, and make daily life more liveable.
What matters, in all these examples, is how nature is framed.
Green roofs and habitat networks are valued for what they do: absorbing rain, cooling neighbourhoods, connecting fragmented habitats, and improving quality of life.
In each case, nature is planned as part of a wider green infrastructure network, linking cities to surrounding landscapes rather than sealing them off from the living world entirely.
None of these places decided that growth required nature to lose. They decided the opposite.
Which leaves Britain’s claim that nature holds us back from growth embarrassingly weak.
What remains isn’t evidence, but politics.
When We Were the Ones Being Watched
Not so long ago, BNG was genuinely exciting.
England was seen as doing something genuinely innovative. Imperfect, yes, but bold.
We were one of the first countries to say, out loud and in law, that development should leave nature measurably better than it found it and that private investment had a role to play in that repair.
Other countries noticed.
I hosted delegates from the Welsh Government at Great Chalfield walking them through how BNG worked in practice. What was promising. What we’d already learned the hard way.
There was a sense then that we were building something worth learning from. That BNG wasn’t just another planning requirement, but a signal that nature recovery was finally being taken seriously as infrastructure and as a credible way to unlock private investment into it.
BNG held promise. It suggested a future where nature recovery wasn’t reliant solely on dwindling public funds or heroic volunteerism, but embedded sensibly and pragmatically, into how we shape places.
Where We Are Now
It’s not all gloom of course. Large developments still fall within BNG. Nationally Significant Infrastructure Projects (NSIPs - another acronym for you) are due to be brought into the framework. Given time, the market may yet recover.
But damage has been done.
Confidence in BNG, and in the government’s willingness to stick with it, has been shaken. And markets don’t fail only because of bad design. They fail because trust drains away.
BNG was not perfect but it needed time, clarity, and care. It still does.
Pulling it apart just as it was beginning to function reinforced the most tired and damaging narrative we have: that we must choose between homes and hedgehogs, prosperity and ponds, growth and green.
We don’t.
We can build homes, good-quality, nature-friendly, energy-efficient, genuinely affordable homes and we can also insist that building contributes to the landscapes it reshapes.
BNG wasn’t a silver bullet. It was a tool. One of the few we had that recognised a simple truth:
If development takes from nature, development should help put something back.
That’s not radical.
It’s just fair.
This is such an important article - I led a walk last year which discussed this new piece of legislation. The reason being is that some environmental restoration company bought some disused quarry close by with the hope of using those 10% set asides to fill the quarry and transform it into a semi quasi nature reserve. In two years nothing has happened except for disputes with homeowners in the area who have extended their gardens. I have my suspicions that nothing will ever happen.
Another excellent piece Carrie. You write so clearly. I am glad you still have hope. I find it hard! makes me so angry.