One of 325 local authorities has an average half-hourly meter as big as it was in 2013: Slough Published dataset: uk-large-site-electricity-data-centres-2026.csv Study page: https://www.servnetuk.com/research/uk-large-site-electricity-data-centres-2026 WHAT THIS IS One row per local authority in Great Britain that appears in the half-hourly (large-site) rows of DESNZ's MSOA non-domestic electricity workbook in any year from 2010 to 2024. n = 378. This is a population, not a sample. It carries the figures needed to recompute every headline on the study page: the large-site intensity test (2013 against 2024), the concentration of change over 2019 to 2023 on two different series, and the data-centre overlay for the three local authorities DESNZ publishes one for. Every figure in this file comes from a DESNZ statistical release under the Open Government Licence v3.0. Nothing was measured, inspected or estimated by us. No individual is named anywhere in this file. DATA AS AT: 2026-09-20 Computed 2026-09-20 from DESNZ statistical releases downloaded 2026-09-20T06:48Z. Half-hourly and subnational data are the 18 December 2025 editions; the data-centre tables are the 30 June 2026 edition. HEADLINE FIGURES, WITH THEIR DENOMINATORS - Local authorities whose average large-site meter is as big as it was in 2013: 1 of 325 Slough, at a ratio of 1.0008. It clears parity by 0.08 per cent, or 0.0014 GWh per meter, so its own position is thin; the count is not, because second place is Hart at 0.6222. See the revisions caveat Denominator: local authorities with more than 100 half-hourly meters in 2013 and present in 2024 - The same test over 2019 to 2023, between the two documented settlement breaks (half-hourly meters still rose 8.5 per cent across it): 6 of 349 Those 6 are at or above their 2019 average per meter, Slough highest at 1.4135; the 2013 to 2024 test gives one, which is consistent with the longer window carrying far more reclassification rather than less real growth Denominator: local authorities with more than 100 half-hourly meters in 2019 and present in 2023 - The median local authority's average large-site meter, 2024 against 2013: 29% interquartile range 0.25 to 0.34 Denominator: each authority's own 2013 mean kWh per half-hourly meter, n=325 - Local authorities using less large-site electricity, 2019 to 2023: 326 of 350 24 used more Denominator: every local authority in the half-hourly panel in both years - Share of all large-site growth taken by the ten largest risers: 94.6% of 1,093.9 GWh of increases, falls not netted off; 99.1% of 941.7 GWh on the migration-immune series, over only 13 rising authorities Denominator: the sum of the increases of the 24 local authorities that used more, 1,093.9 GWh; falls are not netted off - Data centres as a share of Great Britain's large-site electricity, 2024: 3.67% against 1.79% of all electricity, the figure DESNZ publishes. An approximation: an all-meter numerator over a half-hourly denominator Denominator: half-hourly (large-site) electricity in the same area in 2024, 121.5220 TWh - Data centres as a share of Slough's large-site electricity, 2024: 74.6% against 65% of all electricity in Slough, the figure DESNZ publishes. An approximation: an all-meter numerator over a half-hourly denominator Denominator: half-hourly (large-site) electricity in the same area in 2024, 1.7343 TWh COLUMNS la_code: ONS code for the local authority, reconciled: Barnsley E08000016 and Sheffield E08000019 are carried as their post-2016 codes E08000038 and E08000039 so that neither appears twice. la_code_as_published_2010_2014: The earlier ONS code, where it differs from la_code. Empty for every authority whose code never changed. la_name: The local authority name, with the Welsh bilingual second form removed where DESNZ publishes one. la_name_published_2024: The name exactly as DESNZ writes it in the 2024 sheet, bilingual forms included. Empty for authorities that do not appear in 2024. region_or_country: Region or country, from the 2024 subnational workbook. Empty for authorities that no longer exist. first_year_present: First year the authority appears in the half-hourly panel. last_year_present: Last year the authority appears in the half-hourly panel. years_present: Number of years, 2010 to 2024, in which the authority appears. 15 means every year. present_all_2010_2024: 1 if present in all fifteen years, else 0. There is a geography break at 2015, so fewer authorities span the whole period than exist in either half. hh_meters_2013: Half-hourly (large-site) meters in 2013, as published. Empty if the authority is absent that year. hh_gwh_2013: Half-hourly electricity in 2013, GWh, converted from the published kWh. Covers January to December. hh_mean_gwh_per_meter_2013: DESNZ's published mean kWh per half-hourly meter in 2013, expressed in GWh. Not recomputed: the published mean was checked against total over meters on every row and agreed. hh_meters_2019: Half-hourly meters in 2019. hh_gwh_2019: Half-hourly electricity in 2019, GWh. hh_mean_gwh_per_meter_2019: Published mean per half-hourly meter in 2019, GWh. hh_meters_2023: Half-hourly meters in 2023. hh_gwh_2023: Half-hourly electricity in 2023, GWh. hh_mean_gwh_per_meter_2023: Published mean per half-hourly meter in 2023, GWh. hh_meters_2024: Half-hourly meters in 2024. Carries the 2024 reclassification-break caveat. hh_gwh_2024: Half-hourly electricity in 2024, GWh. Carries the 2024 reclassification-break caveat. hh_mean_gwh_per_meter_2024: Published mean per half-hourly meter in 2024, GWh. Carries the 2024 reclassification-break caveat. in_intensity_base_reconciled: 1 if the authority had more than 100 half-hourly meters in 2013 and is matched in 2024 on the reconciled identity. This is the basis the study's headline n uses. in_intensity_base_published_name: 1 if it is matched on the published name with no normalisation. This basis drops twenty-two Welsh authorities, which DESNZ writes monolingually in 2013 and bilingually in 2024. in_intensity_base_published_code: 1 if it is matched on the published ONS code with no recoding. This basis drops Barnsley and Sheffield, which were recoded in 2016. intensity_ratio_2013_2024: hh_mean_gwh_per_meter_2024 divided by hh_mean_gwh_per_meter_2013. Empty outside the reconciled base. This is a ratio of per-meter means, not a measure of demand: settlement migration lowers it wherever it happened. intensity_rank_2013_2024: Rank within the reconciled intensity base, 1 being the highest ratio. intensity_at_or_above_parity: 1 if intensity_ratio_2013_2024 is 1 or more. intensity_ratio_2019_2023_clean_window: The same per-meter ratio over 2019 to 2023, a window that sits between the two documented settlement breaks. Half-hourly meters still rose about 8.5 per cent nationally across it under P322, so the window is quieter than 2013 to 2024, not free of reclassification. Base: more than 100 half-hourly meters in 2019. intensity_rank_2019_2023_clean_window: Rank within that clean-window base, 1 being the highest. hh_gwh_change_2019_2023: hh_gwh_2023 minus hh_gwh_2019. Both years are on the half-hourly January to December basis. hh_direction_2019_2023: up, down or unchanged, from the previous column. hh_riser_rank_2019_2023: Rank among authorities whose half-hourly electricity rose, 1 being the largest rise. Empty for authorities that fell. hh_share_of_total_hh_growth_2019_2023_pct: This authority's rise as a percentage of the sum of all rises. Denominator: the total of the increases only; falls are not netted off. Empty for authorities that fell. all_non_domestic_gwh_2019: All non-domestic electricity in 2019, GWh, from the subnational workbook. Includes half-hourly and non-half-hourly meters, so it mixes a January to December and a February to January year. all_non_domestic_gwh_2023: All non-domestic electricity in 2023, GWh. all_non_domestic_gwh_change_2019_2023: The change on that series. This is the migration-immune measure: a meter reclassified between half-hourly and non-half-hourly settlement stays inside this total. all_non_domestic_direction_2019_2023: up, down or unchanged, from the previous column. all_non_domestic_riser_rank_2019_2023: Rank among authorities that rose on the migration-immune series. Empty for authorities that fell. all_non_domestic_share_of_total_growth_2019_2023_pct: This authority's rise as a percentage of the sum of all rises on that series. Empty for authorities that fell. divergence_ratio_hh_over_all_non_domestic: hh_gwh_change_2019_2023 divided by all_non_domestic_gwh_change_2019_2023, where both are positive. A value near 1 means the half- hourly rise is matched on the migration-immune series. A large value means much of the half- hourly rise is meters arriving rather than electricity arriving. up_on_both_series_2019_2023: 1 if the authority rose on both the half-hourly and the all-non- domestic series. data_centre_area_published_by_desnz: 1 if DESNZ publishes a data-centre figure for this authority. Only three of the eighteen areas in the DESNZ data-centre tables are local authorities. data_centre_sites_2024: Operational data centres DESNZ matched to a meter in 2024. Colocation, managed hosting and hyperscale only; enterprise data centres are out of scope. data_centre_twh_2024: Data-centre electricity in 2024, TWh, as published by DESNZ. An all-meter figure. data_centre_share_of_all_electricity_2024_pct_desnz: DESNZ's published percentage. Denominator: all electricity taken from the grid in the area, domestic and non-domestic. data_centre_share_of_large_site_electricity_2024_pct_approx: Our recomputation. Denominator: hh_gwh_2024 for the same authority. APPROXIMATION: an all-meter numerator over a half-hourly denominator, covering slightly different twelve-month periods. notes: Anything about this row a reuser needs: geography break, code change, bilingual publication, or why it falls outside a base. METHOD Three things. First, electricity per half-hourly (large-site) meter by local authority, 2013 against 2024, as a ratio, over authorities with more than 100 half-hourly meters in 2013. Second, the direction and concentration of change in large-site electricity by local authority over 2019 to 2023, computed twice: once on the half-hourly series and once on the all-non- domestic series that reclassification cannot move. Third, data-centre electricity as a share of large-site electricity, where DESNZ publishes it as a share of all electricity including homes. - All four DESNZ files were downloaded once, with byte size and md5 recorded, and nothing was fetched twice. Requests were sequential, half a second apart, with an identifying user agent. www.gov.uk robots.txt permits the paths used; the assets host serves no robots.txt. - openpyxl is not available in this environment, so the workbooks were read by unzipping the xlsx and parsing the sheet XML directly. Sheets were selected by name, never by position, because the sheet order is not chronological. - Columns were matched by header text, never by position, because the subnational workbook changes its headers in 2012 from 'Domestic' and 'Non-Domestic' to 'All Domestic' and 'All Non- Domestic'. - Only the half-hourly rows of the MSOA workbook were used. Those rows are published by DESNZ at local authority level and carry the MSOA code 'All MSOAs'. No MSOA row was ever aggregated. - The 'Unallocated' rows were kept, flagged and excluded from every total, never silently dropped. - Local authorities were matched across years on a reconciled identity: the published name with the Welsh bilingual second form removed, which gives the same set as matching on the ONS code with the two 2016 recodes applied. All three possible rules were computed and are reported. - The intensity test is the ratio of DESNZ's own published mean kWh per half-hourly meter in 2024 to 2013. The published mean was checked against total kWh divided by meter count on all 5354 local authority rows and agreed on every one, so nothing was recomputed. - The concentration window is 2019 to 2023, chosen because P272 completed on 1 April 2017 and the unexplained break falls in 2024, so the window contains neither. - The migration-immune cross-check uses all non-domestic electricity from the subnational workbook. A meter moved between half-hourly and non-half-hourly settlement stays inside that total, so the total cannot be moved by reclassification alone. - The data-centre overlay divides DESNZ's published data-centre TWh by the half-hourly TWh for the same area and year. It is labelled an approximation because the numerator is an all-meter figure and the two figures cover slightly different twelve-month periods. - Two reconciliations were run as blocking checks before any analysis: DESNZ's published data- centre TWh divided by its published share returns the subnational all-meter total exactly, for Great Britain and for Slough. Both agreed to eight decimal places. - No network access takes place at analysis time. The script reads only local files and is deterministic. Why 2013: P272, with P322 alongside it, moved meters into half-hourly settlement between 5 November 2015 and 1 April 2017, so 2013 and 2014 are both before settlement migration. 2013 is used rather than 2014 because the printed national series moves sharply between them: half-hourly meters rise from 121,327 in 2013 to 145,104 in 2014 and fall back to 127,478 in 2015, across the change of geography basis, so 2014 is the noisier of the two base years. 2013 is the last quiet year in which the half-hourly category meant what it had meant for the previous decade. Why more than 100 meters: Below about a hundred half-hourly meters a single large site moves the mean, and a single reclassification moves it further. The threshold is a judgement, stated here so it can be varied: it excludes 21 of the 371 authorities present in 2013. THE THREE DENOMINATORS IN USE - all electricity: all electricity taken from the grid in an area, domestic and non-domestic. Used by DESNZ, for the data-centre shares it publishes. Great Britain 2024: 249.248 TWh. - large-site (half-hourly) electricity: electricity on half-hourly settled meters, which is DESNZ's own definition of the larger non-domestic sites. Used by this study. Great Britain 2024: 121.522 TWh. - all non-domestic electricity: half-hourly plus non-half-hourly non-domestic meters, as published in the subnational workbook. Used by this study, for the migration-immune cross-check only. Great Britain 2024: 151.744 TWh. CAVEATS - 2024 figure. A large reclassification break appears in the 2024 half-hourly data: half-hourly meters rose 23.6 per cent in one year, or 23.4 per cent with the Unallocated row left out, while total non-domestic meters rose 1.3 per cent, and 344 of the 349 local authorities with at least 100 half-hourly meters in 2023 gained more than 5 per cent. No explanation for it appears in the documents read here. It is not Market-wide Half Hourly Settlement: Ofgem's CR055 decision puts MHHS meter migration between late October 2025 and May 2027, after this data year. Any 2024 figure on this page sits on a meter base that earlier years do not share. - Settlement migration, not demand. BSC modification P272, with P322 alongside it, moved profile classes 5 to 8 into half-hourly settlement between 5 November 2015 and 1 April 2017. Ofgem states the condition: 'These changes only apply to non-domestic businesses that are in profile classes 5-8 and have an advanced meter installed.' The migration was therefore partial, and P322 keeps moving meters after 2017 as businesses change supplier or contract. Half-hourly meters in Great Britain went from 127,478 in 2015 to 265,975 in 2017 while the average per meter fell from 0.9916 to 0.5093 GWh. That fall is reclassification, not a change in electricity use. - Measuring per meter reduces that distortion but does not remove it: the meters that moved in are smaller than the ones already there, so the per-meter mean is pushed down wherever migration happened, which is almost everywhere. The 2019 to 2023 test is reported alongside for exactly this reason: it sits between the two documented settlement breaks. Even that window is not still — half-hourly meters rose 8.5 per cent across it — so it is the quietest window in the data rather than a clean one. - A 'large site' here is a meter, not a building and not a business. DESNZ splits domestic from non-domestic by settlement profile class, with profile 1 and 2 meters reallocated to non- domestic above 100,000 kWh a year, or above 50,000 kWh with supporting address information. A site with several meters counts several times; a single meter serving several businesses counts once. - Half-hourly data covers January to December. Non-half-hourly data covers February to January; the 2024 non-half-hourly year is February 2024 to January 2025. The two are never added here, and the all-non-domestic series used for the migration-immune cross-check contains both, so it mixes the two periods as well. - The data-centre share of large-site electricity divides an all-meter numerator by a half- hourly denominator. It is an approximation and is labelled as one wherever it appears. - DESNZ's data-centre statistics cover 239 operational sites in Great Britain in 2024 and count only colocation, managed hosting and hyperscale sites serving external organisations. Enterprise data centres are excluded, so the scope exclusion pushes the true share above what the overlay shows. A second bias runs the other way: an all-meter numerator sits over a half-hourly denominator, which inflates the figure the overlay reports. Neither has been quantified, so the net direction of error is not determinable from published data. - DESNZ classifies the data-centre statistics as Official Statistics in Development, which in its own words carry a higher degree of uncertainty than Official Statistics. - Geography break at 2015. The 2010 to 2014 years use 2011 Census geographies and carry 370 to 371 local authorities; 2015 onwards uses 2021 (England and Wales) and 2022 (Scotland) geographies and carries exactly 350. No single local authority set spans 2010 to 2024, which is why no figure here is anchored on 2010. - Revisions. DESNZ revises 2015 onwards at each annual publication, as postcode lookups are updated, meter addresses corrected and anomalous year-on-year changes investigated. Years to 2014 are not revised on the same basis. These figures are the 18 December 2025 edition of the half-hourly and subnational workbooks and the 30 June 2026 edition of the data-centre tables. A later edition will not reproduce them exactly. One headline figure is thin enough for that to matter: Slough clears parity by 0.08 per cent, or 0.0014 GWh per meter, so a revision of a tenth of one per cent to its 2024 mean would move the parity count from one to none. Nothing else in the study turns on a margin that fine. - The number of local authorities in the intensity base depends on how an authority in one year is matched to an authority in another. Matching on the published name gives 303, because DESNZ writes twenty-two Welsh authorities bilingually in 2024 and monolingually in 2013. Matching on the published code gives 323, because Barnsley and Sheffield were recoded in 2016. The reconciled basis used here gives 325. The finding is the same on all three. - MSOAs with fewer than five meters are moved to an 'Unallocated' row for disclosure control. In 2024 that row holds 4,132 half-hourly meters and 2.6826 TWh. It is reported separately and is excluded from every local authority figure and from the national large-site denominator. - DESNZ's subnational data excludes Central Volume Allocation users and electricity generated and consumed on site. Some of the largest sites in the country may therefore sit outside the large-site denominator entirely. - Only three of the eighteen areas in the data-centre tables are local authorities. The data- centre overlay can be attached to three authorities and no more. There is no published per- authority data-centre figure for the rest. - Market-wide Half Hourly Settlement will migrate 33 million MPANs between late October 2025 and May 2027. It will contaminate the 2025, 2026 and 2027 data years far more severely than P272 did. Any comparison drawn through those years will need the same treatment this study gives P272, or worse. - The PDF text of the DESNZ special article runs superscript footnote markers into the preceding number, so '2423' is 242 with footnote 3 and '2594' is 259 with footnote 4. 242 matched plus 17 unmatched is 259 identified, and the published tables give 239 operational in 2024. Anyone re- extracting that PDF should not read those as 2,423 or 2,594. - We have not read the current edition of DESNZ's subnational energy statistics methodology note. We could not locate a December 2025 edition at a stable address, and nothing here depends on it: the defence of what is aggregated rests on the cover sheet of the workbook itself. - Nothing here identifies a site, an operator or a person. The unit throughout is a local authority. WHERE THE SOURCES DISAGREE - How much electricity data centres in Great Britain used in 2023 DESNZ, Energy Trends June 2026 special feature: 4.1 TWh, which the article quotes once as its Great Britain total and once as its England and Wales total; the published table gives 4.1268 TWh for Great Britain National Energy System Operator, as reported by DESNZ: 7.6 TWh for Great Britain in 2023 DESNZ ND-NEED, as reported by DESNZ: 2.6 TWh for England and Wales in 2023 Our position: We do not pick between them. This study uses the DESNZ special-feature figures because they are the only ones published by area, and the spread between the three estimates is roughly three to one, which is the honest measure of how well this is known. One ambiguity is DESNZ's own and is left standing rather than resolved: the article rounds the same 4.1 TWh to Great Britain when comparing itself with NESO and to England and Wales when comparing itself with ND-NEED. The published table gives 4.1268 TWh for Great Britain in 2023, and that is the figure used here. - How many data centres there are DESNZ data tables: 239 operational in Great Britain in 2024; 259 identified, of which 17 could not be matched to a meter techUK, November 2024, as reported by the House of Commons Library (3 November 2025 edition): 450 in the UK LBC, 7 September 2026: nearly 500 in the UK Our position: The counts are not measuring the same thing. DESNZ counts sites it could match to a meter, in a defined commercial scope, in Great Britain; the others count data centres in the UK on wider definitions that include enterprise sites. Only the DESNZ count is used here, and only alongside DESNZ's own consumption figures. The 450 figure is techUK's, carried by the Commons Library at footnote 19; the LBC figure is quoted from its article and has not been independently checked. - Data centres as a share of national electricity DESNZ: 1.79 per cent of all electricity taken from the grid in Great Britain in 2024 A House of Lords answer of 27 January 2025, as reported by the House of Commons Library: an estimated 2.5 per cent of the UK's electricity LBC, 7 September 2026: one fifth of the UK's total energy in 2023 Our position: The three figures are not comparable and only one of them is a measurement we can trace. The 2.5 per cent is a parliamentary answer the Commons Library carries at footnote 125, not the Library's own estimate. The LBC figure is quoted as published and has not been independently checked; it says 'energy' rather than electricity and names no denominator, and at face value it sits an order of magnitude above DESNZ's measured share, so it is reported as a position and is not used for anything. Our own figure for 2024, 3.67 per cent, is on a third denominator again, large-site electricity, and is labelled as such everywhere. - What a per-meter intensity measure should be measured over Utility Bidder, February 2026: mean kWh per non-domestic meter, 2020 against 2024, by local authority This study: mean kWh per half-hourly (large-site) meter, 2013 against 2024, on the 2013 large-site base, with a 2019 to 2023 clean-window test alongside Our position: These are different measures and both are defensible. Ours is narrower on purpose: it is restricted to half-hourly (large-site) meters and to authorities that had a large-site base in 2013, where a per non-domestic meter mean is dominated by small meters. The trade runs against us on one point, and it is stated rather than argued away: their denominator, all non-domestic meters, is the one reclassification cannot move, and ours is the one it can, which is why the migration-immune cross-check and the 2019 to 2023 window exist here. We have not independently verified Utility Bidder's figures and do not present them as checked. - Whether the 2024 jump in half-hourly meters has a published cause DESNZ: no explanation appears in the 2024 summary report or on the cover sheets of the three workbooks used here The study brief this work was commissioned against: attributed it to Market-wide Half Hourly Settlement Ofgem CR055, 29 November 2024: MHHS meter migration begins late October 2025 and completes May 2027 Our position: The break is real and measured, and it is not MHHS, which had not begun. Whether DESNZ explains it somewhere we did not look is an open question: the MSOA cover sheet points readers to a subnational energy statistics methodology note for discrepancies of this kind, and we could not obtain a current edition of that note. The break is therefore described here as unexplained in the documents we read, which are named, rather than as unexplained anywhere. PRIOR WORK - Department for Energy Security and Net Zero, Energy Trends June 2026 special feature on data centre electricity consumption in Great Britain, 2020 to 2024 (30 June 2026). Data centres accounted for “around two-thirds (65%)” of all electricity consumed from the grid in Slough in 2024, in DESNZ's own words. How this study differs: Same numerator, different denominator. We recompute it against large-site electricity rather than all electricity including homes. - Utility Bidder, A local authority league table with a per-meter intensity measure (last updated 27 February 2026). Slough highest in the UK on mean consumption per non-domestic meter in 2024, on a 2020 to 2024 comparison. Described here as their page presents it; we reproduce none of their figures. How this study differs: Per half-hourly meter rather than per non-domestic meter, 2013 rather than 2020 as the base year, restricted to authorities that had a large-site base in 2013, with the settlement-migration artefact measured and a second test over a window between the two settlement breaks. Not independently verified. A request with our identifying user agent returned HTTP 403 and we did not disguise it or retry; what we know of their page came back through a general- purpose fetch tool instead. No data from them is used. - House of Commons Library, Data centres: planning policy, sustainability, and resilience (CBP-10315) (3 November 2025 edition held; a 27 May 2026 edition exists and was not retrieved). Carries two figures used here as context, each from a body the briefing itself credits: an estimated 2.5 per cent of the UK's electricity, which the briefing attributes to a House of Lords answer of 27 January 2025; and 48 per cent of electricity consumption in the Dublin area in 2023, which it attributes to the Commission for Regulation of Utilities. How this study differs: National and international context rather than a local authority measure. The Dublin figure is the nearest published city-region measure we found, but the briefing does not state its denominator, so it cannot be set against Slough's 74.6 per cent of large-site electricity or DESNZ's 65 per cent of all electricity as a like-for-like comparison, and it is not used as one. Read from a public mirror of the 3 November 2025 edition; parliament.uk refused our fetcher. Both figures are the briefing's citations of other bodies, not the Library's own estimates. SOURCES - Non-domestic electricity consumption by Middle Layer Super Output Area (MSOA), Great Britain, 2010 to 2024 (Department for Energy Security and Net Zero). File: https://assets.publishing.service.gov.uk/media/69427b3736f089d38be1f1ce/MSOA_non- domestic_elec_2010-2024.xlsx Page: https://www.gov.uk/government/statistics/lower-and-middle-super-output-areas- electricity-consumption md5: b5d5d28623949b003e46332834c05135 (9,857,810 bytes), retrieved 2026-09-20T06:48Z Taken: The half-hourly rows only. In this workbook those rows carry the MSOA code 'All MSOAs' and a local authority name, because DESNZ publishes half-hourly data at local authority level and not below it. Meter counts, total kWh and the published mean kWh per meter, 2010 to 2024. Licence: Open Government Licence v3.0 - Subnational electricity consumption statistics, Great Britain, 2005 to 2024 (Department for Energy Security and Net Zero). File: https://assets.publishing.service.gov.uk/media/69426e905431f4f94d7f0b5e/Subnational_el ectricity_consumption_statistics_2005-2024.xlsx Page: https://www.gov.uk/government/statistics/regional-and-local-authority-electricity- consumption-statistics md5: 4b6ec832be2747350f1a512506d0404a (2,103,254 bytes), retrieved 2026-09-20T06:48Z Taken: Domestic, non-domestic and all-meter GWh and meter counts by local authority, region and country. Used as the migration-immune series: a meter moved between half-hourly and non- half-hourly settlement stays inside the all-non-domestic total, so that total cannot be moved by reclassification alone. Licence: Open Government Licence v3.0 - Energy Trends June 2026 special feature: data centre electricity consumption in Great Britain, 2020 to 2024 (data tables) (Department for Energy Security and Net Zero). File: https://assets.publishing.service.gov.uk/media/6a3e9f32eaee00074150f678/Data_centre_el ectricity_consumption_in_Great_Britain__2020_to_2024.xlsx Page: https://www.gov.uk/government/publications/energy-trends-june-2026-special-feature- article-data-centre-electricity-consumption-in-great-britain-2020-to-2024 md5: 3c91b3ed10c274d3d939e7de409ad4f0 (60,596 bytes), retrieved 2026-09-20T06:48Z Taken: Tables 1 to 3: operational site counts, TWh and the published share of area electricity, for eighteen areas over 2020 to 2024. Licence: Open Government Licence v3.0 Scope: Covers colocation, managed hosting and hyperscale data centres serving external organisations. Enterprise data centres, run by an organisation for its own IT, are excluded, so the scope exclusion pushes the true share above what the overlay shows. A second bias runs the other way: the overlay puts an all-meter numerator over a half-hourly denominator, which inflates the figure it reports. Neither has been quantified, so the net direction of error is not determinable from published data. - Energy Trends June 2026 special feature article: data centre electricity consumption in Great Britain, 2020 to 2024 (article) (Department for Energy Security and Net Zero). Page: https://www.gov.uk/government/publications/energy-trends-june-2026-special-feature- article-data-centre-electricity-consumption-in-great-britain-2020-to-2024 md5: 420aed4ea6b48df0e0beef76ca183bc1 (214,845 bytes), retrieved 2026-09-20T06:48Z Taken: Scope, method and the comparisons DESNZ draws with NESO and ND-NEED. Licence: Open Government Licence v3.0 - Subnational electricity and gas consumption summary report 2024 (Department for Energy Security and Net Zero). Page: https://www.gov.uk/government/statistics/subnational-electricity-and-gas-consumption- summary-report-2024 md5: 44d800f32901bace37c0b73d79b22bdf (1,943,868 bytes), retrieved 2026-09-20T06:48Z Taken: The classification rules: profile class 0 is half-hourly and 1 to 8 are not; profile 5 to 8 are higher-consuming non-domestic meters; profile 1 and 2 meters are reallocated to non-domestic above 100,000 kWh a year, or above 50,000 kWh with supporting address information. Also the statement that the subnational data excludes Central Volume Allocation users and on-site generation. Licence: Open Government Licence v3.0 - Moving to half-hourly energy reads (BSC P272 and P322): a guide for businesses (Ofgem). Page: https://www.ofgem.gov.uk/guidance/moving-half-hourly-energy-reads- bsc-p272-and-p322-guide-businesses Retrieved: 2026-09-20T06:48Z Taken: The P272 and P322 dates and scope, including the condition Ofgem states: 'These changes only apply to non-domestic businesses that are in profile classes 5-8 and have an advanced meter installed.' Licence: Open Government Licence v3.0 - Decision on Market-wide Half Hourly Settlement Change Request CR055 (Ofgem). Page: https://www.ofgem.gov.uk/sites/default/files/2024-11/CR055_decision_document.pdf Retrieved: 2026-09-20T06:48Z Taken: The MHHS migration timetable: migration of MPANs begins late October 2025 and completes May 2027, covering 33 million MPANs. Licence: Open Government Licence v3.0 - Data centres: planning policy, sustainability, and resilience (CBP-10315) (House of Commons Library). Page: https://commonslibrary.parliament.uk/research-briefings/cbp-10315/ Copy actually read: https://majorprojects.org/wp-content/uploads/2026/04/CBP-10315.pdf Edition held: The 3 November 2025 edition, read from a public mirror at majorprojects.org, not from parliament.uk. The mirrored PDF was not compared against an official copy, because no official copy could be retrieved. Retrieved: 2026-09-20T06:48Z, from a public mirror Taken: Comparative context only: the Dublin figure and the national estimates the briefing reports, each with the body the briefing itself credits for it. Licence: Open Parliament Licence v3.0 Limitation: commonslibrary.parliament.uk and researchbriefings.files.parliament.uk both returned HTTP 403 to our identified fetcher, so the copy held is a public mirror rather than an official one. A later edition dated 27 May 2026 exists and was not retrieved, so no figure from that edition is used. - The cost of UK business energy (Utility Bidder). Page: https://www.utilitybidder.co.uk/blog/cost-of-uk-business-energy/ Retrieved: not retrieved by our fetcher (HTTP 403) Taken: Nothing quantitative enters this study. It is credited as prior work, and its published method is described so that readers can see how ours differs. Licence: Third-party publication. Cited as prior art in the method only. No data taken from it. Limitation: A direct request with our identifying User-Agent returned HTTP 403 and we did not disguise it or retry. The description of their method given here came back through a general-purpose fetch tool rather than our own fetcher, and is therefore not independently verified: treat it as our reading of their page, not as checked fact. No figure of theirs is reproduced and no data from them is used. - Why does the UK have so many data centres, why are they controversial, and where are they? (LBC). Page: https://www.lbc.co.uk/article/why-uk-data-centres-where-5Hjdh6R_2/ Retrieved: not retrieved by our fetcher; quoted from a general-purpose fetch tool Taken: Two figures, quoted only to show how widely the denominators differ in general coverage: 'nearly 500' data centres in the UK, and a statement that data centres used one fifth of the UK's total energy in 2023. Licence: Third-party publication. Quoted as coverage under fair quotation. No data taken from it. Limitation: Not independently verified. The quotes came back through a general-purpose fetch tool, not our own identified fetcher, and we have not checked what the one-fifth figure is a fifth of, or where LBC took it from. It is reported here as a quoted position with an unstated denominator, not as a figure we have tested. LICENCE - THREE LICENCES APPLY, AND A REUSER SHOULD CARRY ALL OF THEM 1. Source data. Crown copyright, reused under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/). Attribution required, in these words: 'Contains public sector information licensed under the Open Government Licence v3.0.' 2. Servnet's derived work. The analysis and the derived columns in this file are licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) (https://creativecommons.org/licenses/by/4.0/). That licence requires attribution as a condition: credit 'Servnet, One of 325 local authorities has an average half-hourly meter as big as it was in 2013: Slough, https://www.servnetuk.com/research/uk-large-site-electricity-data-centres-2026' with a link to the study page. 3. Parliamentary material. The House of Commons Library briefing quoted for context is Parliamentary copyright, reused under the Open Parliament Licence v3.0 (https://www.parliament.uk/site-information/copyright-parliament/open-parliament-licence/). Attribution required, in these words: 'Contains Parliamentary information licensed under the Open Parliament Licence v3.0.' One source, the House of Commons Library briefing, is Parliamentary copyright reused under the Open Parliament Licence v3.0, which requires this statement to be carried: 'Contains Parliamentary information licensed under the Open Parliament Licence v3.0.' Utility Bidder and LBC are cited as prior art and coverage under fair quotation, with acknowledgement; no data from either is reused. The published dataset contains no personal data. Every row is a local authority. No individual is named in any output of this study, and the redaction step that stripped the names in the source documents holds them as salted hashes so no name is retained in the repository either. REPRODUCING THIS FILE scripts/research/uk-large-site-electricity-data-centres-2026/analyse.py reads the three tidy panels in data/research/uk-large-site-electricity-data-centres-2026/ and writes all three published files. It performs no network access and is deterministic: running it twice on the same inputs produces byte-identical output. The panels themselves are rebuilt from the raw workbooks by build_panels.py in the same directory, and the raw workbooks carry recorded md5s. CORRECTIONS Corrections and takedown policy: https://www.servnetuk.com/research/corrections