Key information
Request reference number: MGLA271026-0698
Date of response:
Summary of request
I had a query about your June press release related to data centres.
The release says “99 sites delivering around 760MW at peak demand — the equivalent to the electricity use of 750,000 homes.” I can’t find either figure in the accompanying Buro Happold report, which gives operational capacity as approximately 1 GW (p.3) and historic growth as 0.76 GW over 17 years (Figure 16, p.51).
Could someone please confirm: (1) which figure the 760MW is drawn from, and whether it refers to operational capacity, contracted grid capacity or measured peak demand; and (2) whether the 750,000 homes comparison was made on a peak power basis or converted to annual energy using a utilisation assumption?
Our response
The 760MW figure refers to operational IT capacity. It was derived using figures published in the JLL 2025 Data Centre Outlook, which estimated a total London market size of 1,055MW. From this, we subtracted estimates provided to us by JLL of 286MW of live IT load in the Slough Availability Zone, as Slough sits outside the Greater London Authority (GLA) boundary despite being part of the wider London data centre market. This produced an estimated operational IT capacity of approximately 760MW within the GLA area.
The comparison with the electricity use of 750,000 homes was made on a peak power basis, using assumptions developed through a high-level review of available evidence. It was not derived by converting annual energy consumption using a specific utilisation assumption. We recognise that power demand assumptions for homes can vary depending on methodology and source, and therefore the equivalent number of homes should be regarded as an indicative comparison rather than a precise calculation.