The future of grey belt land: planning and sustainability changes

UK developers have long navigated the unique challenges and opportunities presented by different land types - from green belt protections to the potential and limitations offered by brownfield. But now, attention is increasingly turning to a bold new land category that has joined the planning party: grey belt. These underused parcels on the urban fringe are firmly in the spotlight, as developers, planners, and local authorities seek smarter land solutions to address the housing crisis and deliver on sustainability targets.

In 2025, these specific plots of land aren’t just on the radar; they’re playing a leading role in land strategy. As pressure builds to deliver more homes whilst meeting net zero goals, grey belt is emerging as a practical - yet complex - opportunity.

With many question marks still around where much needed housing can be built while striving to meet net zero goals, grey belt land has merged as a viable new option for development. The catch? To succeed, grey belt needs smart planning, environmental accountability, and a shift in mindset from "leftover land" to strategic asset.

So, let’s get specific. What’s happening with grey belt land in 2025, and where are we headed next?

Planning changes to watch in 2025

Grey belt might offer more flexibility than the traditional circumstances for green belt release, but it’s still subject to heavy scrutiny. Current planning policy - with the updates to the National Planning Policy Framework - is shaped by two big pressures: the housing supply crunch, and the speed at which new infrastructure can be delivered. These stumbling blocks require a concerted effort, with purposeful collaboration between the public and private sectors, to see the fruitful delivery of lasting housing and infrastructure solutions.  

Here is what’s driving grey belt from fringe to front-runner.

1. Councils are hurriedly re-evaluating green belt boundaries

Grey belt land typically occupies that awkward middle zone; not quite green enough to be preserved as designated green space yet not classified as brownfield either. Some local authorities are starting to review these sites as part of their Local Plan reviews, especially in cases where land:

• Has low environmental or recreational value

• Sits close to existing infrastructure

• Has already been partially developed or neglected

But not everyone’s convinced. The National Planning Barometer 2025 suggests that just 34% of councillors believe grey belt plans would preserve the integrity of the green belt, and less than half think it will provide enough land for housing. This highlights the need for clearer planning frameworks and evidence-based engagement to build confidence in grey belt’s role in future development.

2. Brownfield development is always encouraged but grey belt can deliver practical wins

Brownfield regeneration is generally widely supported – and rightly so. But as anyone who’s tackled brownfield land, such as a former factory site, knows, it can be a big project. That’s why it’s so important to identify the right opportunities for the right sites.

This is where grey belt shines. It's developable without the same clean-up costs, and it's often better connected than deep rural land. Plus, it's easier to design in line with 15-minute neighbourhood principles - compact, walkable, and community-oriented. With the right use cases, grey belt could offer a more effective route to delivering much-needed housing than some brownfield alternatives

3. Design specifications are getting stricter yet greener

The National Model Design Code can’t be a “nice-to-have". Councils are starting to enforce stronger design standards, and that includes how grey belt development integrates:

• Active travel routes (yay, cycling lanes!)

• Tree canopy over and rainwater harvesting

• Public transport links

• Aesthetic quality  

If you’re thinking grey belt equals bland suburban sprawl - think again. The trend is towards placemaking, not just housebuilding.

At the Property Build Show 2025, Jack Johnson, TerraQuest’s Head of Land, spoke on the future of the grey belt:

“Grey belt isn’t a silver bullet, but it is a real opportunity. With the right data, partners, and approach, we can unlock land that’s been overlooked for decades.

The idea is: let’s not treat every part of the Green Belt as sacred. Let’s find the land that’s already lost its green value and unlock it for homes, infrastructure, and communities.”

On top of that, Biodiversity Net Gain (BNG) is currently mandatory for nearly all developments. At present, every new development must deliver at least a 10% net gain - even on greenfield and brownfield sites. That means wildlife corridors, green roofs, restored habitats, and auditable BNG plans.  

To explore how BNG is reshaping development, read our full report: Biodiversity Net Gain: The Story So Far.

The sustainability sweet spot

Let’s talk strategy: grey belt offers a rare balance of location, build out potential, and opportunity for increased sustainability. But to meet net zero targets, it’s not just about putting homes down and adding a bike rack.

We’re seeing savvy developers approach grey belt with a more holistic model:

• Carbon modelling baked into early site planning

• Heat pumps and solar from day one (not retrofitted)

• Integrated landscape architecture to support wellbeing and climate resilience

But location should still trump labels. As Dr Victoria Hills, Chief Executive of the RTPI, recently said when asked about grey belt during a panel at UKREiiF:

"It’s a distraction. We should be focused on location, location, location and getting it right. Getting it right needs to be about a sustainable location with a local plan and a community approach. Not whether it’s grey or green."

This reinforces the point: grey belt has potential - but only when it’s the right land, in the right place, with the right strategy behind it.

From land parcel to planning case

Grey belt development isn’t just about identifying the right site - it’s about building the case.

At TerraQuest, we support clients across the UK to:

• Use GIS and planning intelligence tools to assess land viability

• Navigate local plan policy and emerging spatial frameworks

• Build evidence-based planning submissions that align with BNG and NPPF reforms

Book a call with our land consultants today.    

TL; DR:

• Grey belt land is under the spotlight in 2025

• Councils are rethinking green belt boundaries

• Grey belt supports 15-minute neighbourhoods and cost-effective development

• But not everyone’s sold, planning experts warn against focusing too much on land labels

• Get strategic - because the next wave of sustainable growth might just be... grey

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