Summary
- CoStar estimates the UK currently has around 3.5GW of installed data centre capacity.
- A further 1GW is reported to be under construction.
- The figures measure today's physical market more directly than longer-term announced pipelines, but do not remove grid and planning constraints.
The UK’s installed data centre capacity has reached approximately 3.5GW, with a further 1GW under construction, according to the first quarterly UK Data Centre Report from CoStar Analytics.
The figures provide a different view of the market from the much larger pipelines frequently attached to planning applications, grid queues, and long-term AI development proposals. Installed capacity measures infrastructure that has reached operation, while capacity under construction has moved materially further through the delivery process than an announced project.
Even the 1GW construction figure is not equivalent to immediately available customer capacity. Projects have to move through phased commissioning, fit-out, testing, and customer deployment before their full electrical load appears on the system.
The UK remains one of Europe’s largest data centre markets, centred historically on London and the Thames Valley but increasingly extending towards other regions where land, grid access, and planning conditions can support larger developments.
The geographical spread is being driven partly by the difficulty of securing additional power around mature clusters. Slough and west London retain large connectivity and customer ecosystems, but the value of those advantages diminishes if new high-voltage connections cannot be obtained within a commercially workable programme.
DataCentral reported separately on BloombergNEF’s forward capacity outlook. The CoStar numbers are distinct because they describe the current installed base and projects already under construction rather than a longer-term market forecast.
That distinction is increasingly important as AI-driven projects inflate headline pipelines. A proposed campus can enter the public record years before it has a deliverable grid connection, completed planning process, financing, or an anchor customer. Installed and construction-stage figures give a more conservative view of infrastructure that has moved beyond those earlier milestones.
Power nevertheless remains the principal limiting factor. Recent UK industry work has identified connection availability and timing as central investment risks, with the location and value of development land increasingly tied to credible power access.
Growth beyond London will therefore depend less on whether regions can attract development announcements than on whether projects can coordinate grid capacity, planning, fibre, water where required, equipment procurement, and construction programmes.
The 3.5GW installed figure confirms the scale already reached by the UK market. The more consequential number over the next several years will be the proportion of the much larger announced pipeline that can move into the same category.
