London data centre planning momentum measures how quickly qualifying projects are entering and moving through the planning system compared with the historical norm. According to the London Data Centre Planning Index from Authority Inc, the index stood at 119.5 for the trailing 12 months to June 2026, against a fixed baseline of 100. That is about 20% above the 2021 to 2024 average, but far below the early-2026 peak of roughly 259.
Quick Answer
London data centre planning momentum is a score built from first filings and first approvals, minus first refusals or withdrawals, over a rolling 12 months. A score of 100 equals the 2021 to 2024 average. The latest reading of 119.5 means planning activity is still above normal after a sharp 2025 surge. It does not mean those projects will be built, powered or operated.
What Does the London Data Centre Planning Index Measure?
The index counts planning milestones, not buildings. Authority Inc joins related applications and documents into a single project record, then counts three events once per project: the first qualifying filing, the first approval and the first refusal or withdrawal.
The latest reading rests on a very small count. Three new filings plus four approvals minus one refusal or withdrawal gives six net milestones in the trailing year. Based on the published series, each net milestone is worth roughly 20 index points, so a single approval can move the headline score noticeably.
The reading that follows is straightforward: treat the index as a directional signal about planning activity, not a precise gauge of market health.
Why Did London Data Centre Planning Momentum Spike and Then Fall?
The 2025 surge was a filing wave. The index rose from 59.8 in February 2025 to 179.3 in April 2025 as a cluster of qualifying projects entered planning, then peaked at about 259 between December 2025 and February 2026.
The fall since then is largely mechanical. As those 2025 filings roll out of the 12-month window faster than new milestones replace them, the score drops. It reached 199.2 in March 2026, 139.4 in April and 119.5 by May and June.
Isabella L.B., PhD, a senior land and development specialist at AtkinsRéalis, told Authority Inc that the number and maturity of genuine proposals entering the system matters most. A filing wave can lift momentum long before it says anything about construction. Her view is a planning and development perspective, not data centre engineering or investment advice.
What Does London’s Data Centre Planning Pipeline Look Like?
Authority Inc monitors 50 qualifying projects, found by joining 566 matching public planning records. A further 78 uncertain or non-comparable groups are withheld. The August 2026 snapshot shows how the pipeline is distributed:
- Pre-consent: 1 project
- In planning: 6 projects
- Approved: 26 projects
- Construction verified: 1 project
- Build complete (planning record): 10 projects
- Operational verified: 0 projects
- Refused or withdrawn: 6 projects
The most important line is the last of the delivery stages. Approvals dominate the pipeline, while only one project has verified construction and none has independently verified operational status. Build complete means the planning authority recorded finished building work. It does not prove the facility is powered or in service.
Recent approvals show the range of scheme types. Ealing’s committee granted the former Honey Monster factory site in July, subject to conditions, a Section 106 agreement and mayoral referral. Hounslow approved the Heathrow Estate outline application in August for a scheme with 48 MW of IT load. Both still face open questions on power delivery.
Why Is Power the Main Constraint on London Data Centres?
Electricity access is the clearest system-wide limit on delivery. City Hall reports about 760 MW of current peak data centre demand across 99 operating London sites, with more than 8 GW sitting in the connection queue. That queue is over ten times current demand.
A queue that large cannot all be built. The Authority Inc data centre outlook draws a clear line between planning consent and a usable grid connection, and two recent developments show why.
Grid investment is arriving
On 13 August 2026, National Grid launched its North West London Upgrade, which includes a new substation, 60 km of new cable and more than 200 km of upgraded overhead line. National Grid says it will enable new connections including five data centres.
Regulators are targeting speculative demand
On 29 July 2026, Ofgem proposed tougher tests for data centre grid connections, aimed at freeing capacity by tackling speculative projects after contracted demand offers rose sharply. The likely effect is a smaller but more deliverable connection queue.
The practical conclusion is that an approved site without a credible connection route may never reach operation.
Where Might London-Linked Data Centre Growth Happen Next?
Power and land availability are pulling large schemes away from established clusters. JLL analysis cited by Authority Inc found that European hyperscale data centres due to open within two years will sit an average of 175 km from major urban hubs, compared with 46 km for projects delivered between 2022 and 2025. London is among the markets analysed.
Signs of this shift show up inside London too. A proposal surfaced in Charlton for around 180 MW of computing capacity across 100,000 square metres of floorspace, and East Havering has an announced 600 MW campus that is still pre-consent. Authority Inc cautions that it is too early to call this an eastward shift. Demand may stay tied to London while the physical sites move to secondary or edge-of-London locations.
Demand itself remains strong. AWS added a fourth Availability Zone to its Europe (London) Region on 19 August 2026, though it does not disclose where the new infrastructure sits, so it is a stronger signal of demand than of location.
How Should Investors and Developers Read Planning Data?
Planning data is most useful as one input among several. A few principles follow from the Authority Inc evidence:
- Separate consent from delivery. Approval, construction, grid connection and operation are four different milestones.
- Check power first. Ask whether a named site has a credible connection route, since the queue exceeds demand many times over.
- Read the index with its sample size in mind. Six net milestones means small changes produce large swings.
- Look at the stage mix. A pipeline dominated by approved but unbuilt projects says little about near-term capacity.
- Watch the filters coming. Ofgem’s readiness tests may remove weaker schemes from the queue.
Authority Inc’s data centre intelligence is designed around this separation between planning activity and delivered capacity.
The Takeaway for London Data Centre Planning
London data centre planning momentum is above normal at 119.5, but the number describes filings and approvals, not computing capacity. The next phase will be decided less by how many approvals are granted and more by which projects can prove credible power, finance and delivery routes. For anyone assessing the market, the Authority Inc London data centre planning momentum index offers a dated, consistently defined view of planning activity that should be paired with separate evidence on grid readiness and construction.
Frequently Asked Questions
What is the London data centre planning momentum index?
It measures how much qualifying project activity is moving through London’s planning system. Each project’s first filing and first approval add one, and its first refusal or withdrawal subtracts one. Authority Inc rebases the 2021 to 2024 average to 100 and does not cap the score.
Does planning approval mean a London data centre will be built?
No. Approval does not prove that construction, grid connection, commissioning or operation will follow. In the August 2026 Authority Inc snapshot, 26 projects were approved, one had verified construction and none had verified operational status.
What is the biggest constraint on new London data centres?
Electricity access. City Hall reports about 760 MW of current peak demand and more than 8 GW in the connection queue. Grid upgrades and Ofgem’s proposed reforms aim to improve deliverability, but timing for individual projects remains uncertain.
Why did London data centre planning momentum fall in 2026?
Mainly because the large 2025 filing wave began leaving the rolling 12-month window. The score fell from about 259 in early 2026 to 119.5 by June, which is still roughly 20% above the historical baseline.