Data dive: London and M4 the datacentre hotspot, but not for long | JP
The UK’s existing stock of datacentres is smaller, and more concentrated around London, than most of the numbers in circulation suggest.
An analysis of the government’s Energy Performance Certificate (EPC) registers, which JP compiled, counts around 90 existing datacentres across England, Wales and Scotland, with an estimated 1.6GW of capacity. Nearly three-quarters of that sits in London and the M4 corridor.
That existing capacity sits below a far larger projected build-out, however. JP’s analysis of Barbour ABI construction data puts the committed pipeline – projects in planning but not yet built – at 173, and more than 14.6GW – several times more capacity than what’s running today, committed and waiting to be built.
The surviving datacentres are unevenly spread. London and the M4 corridor account for 57 of the 88 existing datacentres – about two-thirds of the sites – and about 1.1GW of the 1.6GW total, nearly three-quarters of the capacity.
The next-biggest regions trail far behind: the Home Counties and South East hold about 150MW, the M62 corridor about 130MW, and the Midlands about 70MW. Scotland holds just a handful of existing datacentres, totalling about 20MW.
That concentration reflects the economics of internet infrastructure. The densest fibre, the deepest pool of network interconnection and the largest concentration of financial and enterprise demand all sit in and around the capital, and datacentres cluster where the cables meet.
Operators such as Telehouse, Global Switch, Equinix and Iron Mountain run several buildings each on the London and Slough campuses that anchor the stock.
The pipeline heads north
The planned pipeline tells the opposite story. JP’s September analysis found 173 committed projects and 14.6GW.
The largest individual schemes now sit in the North East, where nine projects average 228MW, and in Scotland, where 14 average 184MW. The M62 corridor averages 128MW across 23 projects. By contrast, the average committed project in London and the M4 corridor is about 77MW – even though the region still accounts for 82 of the 173 projects and 5.2GW, the most capacity in absolute terms.
Between March and September, the committed pipeline grew from 114 projects and roughly 10GW to 173 projects and 14.6GW – an increase of nearly 60 projects and about 4.6GW in six months. Scotland’s committed pipeline more than tripled, from four projects to 14. That pace has manifested in opposition to datacentre development in communities and a pause on development agreed in the Scottish parliament this week.
The North’s appeal is land and power. Former power stations and heavy-industrial sites offer brownfield space with existing high-capacity transmission connections, at a time when grid access is the scarcest resource in the sector, as the decision to grant the first Nationally Significant status to a Buckinghamshire landfill datacentre makes plain.
The methodology behind the data
The figures come from two steps: identifying the datacentres, then verifying or estimating their capacity.
For the identification, the analysis draws on the non-domestic Energy Performance Certificate registers for England, Wales and Scotland, which hold certificates for more than 57,000 large buildings.
Each building is scored and filtered for traits that might indicate it is a datacentre – high-energy intensity, datacentre property types, electric heating and known operator names – and every candidate is then verified against planning records, operator directories and press reporting. That left 88 existing datacentres, with a further 20 buildings that share a campus.
For capacity, the analysis uses a three-tier estimate. Where a facility publishes its power figure, in operator materials, industry directories or press reporting, that figure is used; 27 sites carry published figures totalling about 707MW, including Microsoft’s 96MW campus at Park Royal and NTT’s 64MW London 1 campus in Dagenham.
Where no figure is published, capacity is modelled from floor area: colocation sites use a density of about 1,166 watts per square metre, calibrated from the published sites, while enterprise and telecoms sites use about 800 watts per square metre. Those modelled sites add roughly 859MW, bringing the total to about 1.6GW, with a plausible spread of 1.3GW to 1.9GW depending on the density assumptions.
These figures are estimates, not metered load, and the register is a lower bound: it misses buildings below about 2,000 square metres and very new or not-yet-certified sites. The regional split uses the same postcode classifier across the existing and planned datasets, so the two are directly comparable. The planned-pipeline figures use a four-tier method: actual published megawatts, a floor-area model that explains about three-quarters of the variance in published capacity, press and trade estimates, and manual review.
The grid is the question
The gap between the two halves of this picture is the conclusion. A modest, London-concentrated estate of about 1.6GW is running today. A pipeline of more than 14GW is committed and, in its largest schemes, heading towards England’s north and Scotland.
The question is not whether the UK can build more datacentres. It is whether the grid can connect what is already committed – and whether the next wave of capacity will stay as concentrated in London as the last. The answer will determine the shape of the UK’s digital geography for a decade.