The grid electricity Irish data centres used caused about 1.46 million tonnes of CO2 in 2025: 2.8% of national emissions excluding land use and 23.2% of the electricity sector's (our estimate: CSO share × EPA sector emissions, Oct 2026). On-site gas is extra; EU ETS-verified on-site emissions were 9.5 kt in the latest year.
Data-centre emissions against the two climate ceilings
Grid power for data centres made 1.46 Mt CO2 in 2025, 37% of the electricity sector's average yearly ceiling for 2026–30. The on-site gas already licensed could fill 63–95% of a much smaller ceiling (the upper figure includes EdgeConneX's maximum case), though measured on-site emissions were only 9,471 tonnes in 2025.
Ireland's carbon budget splits emissions into sector ceilings. Data centres' grid electricity counts in the Electricity ceiling, which averages 4 Mt a year for 2026–30 while the whole sector emitted 6.3 Mt in 2025; data centres' share, by their share of metered electricity, was 1.46 Mt. Gas burned on site counts in the Commercial and Public buildings ceiling (1 Mt a year), where EPA inspectors place it: at the figures in their reports, the licensed data-centre gas plant would emit about 0.95 Mt a year, but that total includes EdgeConneX's maximum run-on-instruction case, so read it as an upper bound; without it the figure is 0.63 Mt (63%). EU ETS verification measured 9,471 tonnes from data-centre installations in 2025, far below that licensed potential.
EstimateGrid emissions are an average (attributional) allocation: data centres' share of metered electricity × electricity-sector emissions. Imports count as zero in Ireland's inventory. The 500-hour line assumes every licensed gas MWth ran only 500 hours a year.
A year from three licensed gas sites, at the EPA inspectors' stated figures (EdgeConneX's is its maximum, run-on-instruction case)
EPA inspectors' figures
63–95%
Of the commercial buildings ceiling, which their gas counts against (per EPA inspectors)
1.0 Mt a year average, rounded · sector already at 1.392 Mt in 2025
Two different ceilings. Grid power counts against the electricity ceiling; gas burned on site counts against the commercial and public buildings ceiling (per EPA licence inspectors). Three licensed gas-powered data centres would use about 95% of that sector's yearly budget for 2026–30. Today, on-site emissions are only about 9.5 kt: this is about what happens if they start.
CO₂ from data centres' grid electricity (Mt)
2017 · 1.8 TWh0.79
2018 · 2.2 TWh0.83
2019 · 2.5 TWh0.84
2020 · 3.0 TWh0.93
2021 · 4.0 TWh1.38
2022 · 5.3 TWh1.70
2023 · 6.3 TWh1.55
2024 · 7.0 TWh1.50
2025 · 7.7 TWh1.46
Data centres' share of metered electricity × electricity-sector emissions (EPA). Falling intensity has offset rising demand since 2022.
Stated CO₂ of gas-powered sites (kt a year)
Echelon Clondalkin · P1113379
EdgeConneX · P1204314
South Dublin Routing 4 No. 2 · P1210252
Data And Power Hub Services · P1165204
Microsoft · P118752
From EPA inspector reports. Licensed does not mean running: most have not started. Data And Power Hub is a grid peaker, so its gas likely counts under the electricity ceiling instead.
EPA GHG inventory and projections · Sectoral Emissions Ceilings (2022) · EPA licence reports · EU Union Registry · CSO · as of 2026-10-10
The on-site gas total counts EdgeConneX's licensed run-on-instruction case at its maximum (about 0.31 Mt a year, EPA inspector's report). Read the on-site share as an upper bound; without that case it is about two-thirds of the figure shown.