How Many Data Centres in the UK Are There Devouring Energy?

Executive summary

No one publishes an official count of UK data centres, so the useful question is how much capacity exists and how much electricity it uses. The best official figures are these. DSIT estimates Great Britain's colocation IT capacity at 1.6 GW (Autumn 2024). DESNZ puts data centres' share of GB grid electricity at 1.8% (2024). NESO projects 20 to 41 TWh (Falling Behind 20; Hydrogen Evolution 30; Ten Year Forecast 33; Holistic Transition 37; Electric Engagement 41) (By 2035 - FES 2025 pathways) by 2035. Every figure below is sourced, and the Index figures update automatically (Electricity Demand Index, Data Centre Growth Index).

Why this matters for the UK

Data centres are one of the few new sources of electricity demand that arrive in large, concentrated blocks at particular network locations. The government's AI Opportunities Action Plan and the UK Compute Roadmap both assume compute capacity will grow significantly. The Roadmap puts the requirement for AI-capable capacity at At least 6 GW (By 2030 (UK Compute Roadmap forecast)) (Index). The House of Commons Library notes that other forecasts for 2030 range from 3.3 to 6.3 GW. That spread is itself a sign of how uncertain the outlook is.

How many data centres are there?

There is no official site count

The original version of this article quoted an industry estimate of 500 to 600 sites. We could not trace that figure to a primary source, so it has been removed. The nearest official measure is DSIT's Estimate of data centre capacity, Great Britain, 2024. It measures IT capacity at colocation facilities rather than counting buildings, and puts the GB total at 1.6 GW (Autumn 2024).

Where the capacity is

DSIT's regional breakdown shows how concentrated capacity is. London alone accounts for 1,048 MW (Autumn 2024), compared with 128 MW (Autumn 2024) in the South East and 154 MW (Autumn 2024) in Wales. The full regional series is on the Data Centre Growth Index. Individual projects, with planning references and verification dates, are listed in the UK Data Centre Tracker. The tracker is a sample of documented projects, not a census.

Projects in our tracker (3 November 2026)

Our UK Data Centre Tracker holds 64 published data-centre projects plus the 5 AI Growth Zones: 11 operational, 5 under construction, 28 approved, 9 with a planning application in, 9 proposed, 1 paused and 1 refused. The live totals are always on the tracker page. Six projects have a recorded refusal at some point, several later allowed on appeal; they are listed in the refused and withdrawn register. You can see every site on the UK AI data centre map, or browse by nation: Scotland, Wales, Northern Ireland, London, North East and North West. Each scored project carries a Reality Score showing how likely it is to be built.

How much electricity do they use?

Measured: DESNZ

DESNZ's Energy Trends (June 2026) reports GB data-centre electricity consumption of 4.5 TWh (2024). It puts their share of grid electricity at 1.8% (2024). Between 2020 and 2024, consumption rose by 41% (2020 to 2024) (Electricity Demand Index). Energy Trends also puts data centres' share of electricity in Slough at 65% (2024), which shows how concentrated the load can be locally.

Modelled: NESO

NESO's Grid Code Development Forum pack (5 November 2025), which quotes its Future Energy Scenarios 2025 figures, uses a broader definition and gives a modelled estimate of 7.6 TWh (NESO modelled estimate as at November 2025). It reports 2.4 GW (As at November 2025) of connected data-centre capacity. The DESNZ and NESO figures measure different things. They should not be averaged or treated as competing answers. The Index shows both, with their definitions.

AI's share is not known

No official source separates AI workloads from other data-centre electricity use. The Index therefore shows AI-attributable demand as Insufficient evidence.

What happens next?

NESO projections

NESO's FES 2025 pathways project GB data-centre demand of 20 to 41 TWh (Falling Behind 20; Hydrogen Evolution 30; Ten Year Forecast 33; Holistic Transition 37; Electric Engagement 41) (By 2035 - FES 2025 pathways) by 2035. Its Clean Power 2030 advice uses 14.6 TWh (2031 (NESO Ten Year Outlook 2026)) for 2030. These are scenario outputs, not forecasts of what will happen. The original article's claims that demand would "double by 2030" and "triple by 2040" were not sourced and have been removed.

International context

The House of Commons Library briefing CBP-10315 summarises international data. Data centres used about 1.5% of global electricity in 2024. The IEA's base case sees that approaching 3% by 2030, within a scenario range of roughly 2% to 4.4%. US estimates reach up to 12% by 2028, and data centres account for around one-fifth of Ireland's national demand. The same briefing notes that UK industrial electricity prices were about 63% above the IEA median in 2024, including taxes. This matters when operators compare the UK with other locations.

Grid constraints: local, documented

Grid pressure from data centres shows up locally, in network operators' own planning documents. UK Power Networks' DNOA Outcomes Report (March 2025, p.49) records an expected overload at Bow grid supply point from winter 2026 and a capacity shortfall around Willesden in West London. SSEN's Iver 132kV Strategic Development Plan (May 2025, p.19) reports over 600 MVA of data centres connected and contracted across the Iver supply area, which serves Slough. Nationally, the Grid Pressure Index tracks the all-sector connection queue at 125 GW (June 2025). That is contracted capacity, not demand, and the data-centre share is Insufficient evidence — sources conflict (Not established). Proposed changes to how connections are allocated are covered in Ofgem's proposed data centre connection reforms.

Practical implications

• Ask which measure a figure uses: site counts, IT capacity, grid connection capacity and annual electricity use are not interchangeable. See why megawatt announcements can mislead.

• Treat planning approvals as intentions, not delivered load. See what is actually built, approved or proposed.

• Local network documents are the best evidence of where data centres are straining the grid.

What remains unknown

• How many data-centre sites the UK has. No official count exists.

• How much capacity sits outside colocation, at enterprise and hyperscaler self-built sites.

• How much data-centre electricity is used by AI.

• Northern Ireland, which is outside the DESNZ and NESO GB figures.