Sadiq Khan Loosens London's Green Belt for Data Centre Plans

The Mayor of London, Sadiq Khan, looks set to allow the construction of data centres across London's 'green belt', an area of countryside that has been protected from overdevelopment since the Second World War.

The announcement came in the form of the London Plan, the first draft of which was published on 16 July, wherein the Mayor laid out his plans for the capital's spatial development strategy pending a three-month consultation period.

Within the green belt – which encircles London completely – is a newer, more contested category of land known as the 'grey belt'. 

This is land that technically falls within the green belt but is considered low quality or already degraded. As a result, planners believe these areas are suitable for development.

It is this grey belt land that Sadiq Khan is most likely to open up to data centre developers. But while the news will have been welcomed by hyperscalers, the mooted plan has not been received positively across the board.

Are data centres getting special treatment in London?

The UK's green belts were first introduced to stop urban sprawl and preserve areas of natural beauty, though there has been always been certain exceptions to the rules.

Development in these areas has traditionally been confined to areas with transport links that are earmarked for housing. The new permissions for data centres, however, bucks this trend.

In the new London Plan, the Mayor describes data centres as the "only exception".

But why data centres and why not, say, factories or warehouses?

The justification is that data centres do not generate the same kind of traffic and logistical activity as other commercial buildings once they are operational, since they generally only need a few staff to run day to day.

That has allowed officials to argue that data centres should be assessed differently from other kinds of industries.

Giles Pink, a Partner at Bryan Cave Leighton Paisner, told The Telegraph the resulting policy as "quite permissive", noting that data centres now "have a bit more privilege in this emerging policy" compared with other sectors.

The question of energy

Sadiq Khan's plans for London's burgeoning data centre sector hinge just as much on energy as they do on land. Speaking last month, the Mayor laid out his vision.

“My ambition is clear, I want London to become the world’s leading city for environmentally-friendly, low-emission, high-efficiency data centre development, and AI infrastructure so that our capital remains a leading global hub for digital innovation,” he said.

"The energy requirements of data centres are colossal, so delivering their expansion at pace alongside London’s other infrastructure needs will require more coordinated planning."

These sentiments are backed up by the London Assembly Planning and Regeneration Committee, the body which holds the lead role in scrutinising the Mayor's London Plan.

"The provision of electricity is critical and will only become more so in the years ahead. As a result of this reliance, when the grid can’t keep pace with demand, the consequences are immediate," James Small-Edwards, Chair of the Committee, said back in December 2025.

"The government wants the UK to lead the way globally in artificial intelligence and digital innovation. Bold goals that, if successful, will drive huge demand for data centres, which are often staggeringly energy-intensive.

"But if we don’t plan ahead, we run the risk of not meeting those ambitions, or realising those ambitions at the expense of urgently needed housing and infrastructure."

Renewables will be central to this kind of planning, as will the country's ongoing Great Grid Upgrade. As regards energy, the London Plan states that proposals for new data centres must demonstrate a few key things, including:

1. Coordinated heat recovery infrastructure that is informed by a waste heat utilisation plan   
2. Coordinated electricity and water efficiency measures including innovative cooling technologies
3. Where feasible, electricity generation on-site or nearby from renewable energy sources

These stipulations would force any developments on London's green belt to be designed sustainably and with circularity built in.

Heat recovery and circularity in new data centres

Heat recovery, the first stipulation in the list above, has become a big part of the data centre conversation lately.

The computers in data centres produce a huge amount of heat which is why they require constant cooling.

The idea of heat recovery is all about making use of this thermal energy, using it to heat nearby buildings rather than wasting it.

Though it sounds complex, data centres are already often used as the 'engine' of district heating networks like this. With companies like Veolia already investing huge sums in London's district heating systems, new data centres in the green belt could help to contribute.

This sort of system has been used to striking effect in Milan recently, where Equinix's data centres are being used to heat buildings across the city, including the Duomo which is among Italy's most iconic buildings.

“Equinix has a long and proud history of aligning the needs of our business with the needs of the communities we call home," says Adaire Fox-Martin, the firm's President and CEO.

“Our collaboration with A2A is a clear example of how essential digital infrastructure and local sustainability goals can work in service of each other.

“By putting thermal energy from our operations to use for local homes and residents, we're eliminating waste and moving Milan toward a low-carbon future.”

Can the Mayor get everyone on side with this plan?

While the Mayor's plan will make sustainability a key consideration for new data centres in the green belt, some people will still need convincing that this is a good idea, including environmentalists and politicians.

Andrew Rosindell, the MP for Romford, spoke to The Telegraph about the plans.

He warned the new plan risks "setting a dangerous precedent by making it easier to build large-scale data centres on green-belt land".

Andrew was careful to stress he was not opposed to the technology itself, saying he was not "opposed to data centres given their rapidly growing importance".

But he argued expansion "should not come at the expense of the countryside that local communities value".

The tension he describes, between Britain's AI ambitions and its planning traditions, looks set to define data centre development across the capital for years to come.