Data centres consumed one-third more electricity in 2021 compared to 2020.
Figures from the Central Statistics Office (CSO) show last year they used up 14% of the metered electricity supply.
That compares to just 5% used back in 2015.
Meanwhile, overall there was a 5% increase in electricity consumption in 2021 compared to the year before.
Median residential metered electricity consumption was 3,594kWh - and around 10% of residential customers consumed less than 1,000 kilowatt hours.
In residential consumption, urban groups consumed the most - at 21% - and rural groups used 12% of the total metered electricity consumption.
Dublin postal districts had the highest proportion at 18%, followed by Cork (12%), Dublin county (7%), Galway (6%) and Kildare (5%).
Donegal, Leitrim and Roscommon had the lowest median residential consumption last year, while Kildare had the highest figure.
January to March had the highest median consumption.
While consumption by large energy users increased by 17% between 2020 and 2021 - and by 80% between 2015 and 2021.
CSO statistician Niamh Shanahan says: "Large energy users accounted for 23% of metered electricity consumed in 2021.
"This category comprises a small number of customers, such as the largest data centres and the highest electricity consumers in other business sectors such as IT and cement manufacturing."
She adds: "The number of non-residential electricity meters increased from 274,094 in 2015 to 290,384 in 2021, while the number of residential electricity meters increased by around 106,000 in the same period.
"Electricity consumption can be used as an indirect indicator of vacant and holiday dwellings."
Non-residential consumption was 67% of total metered electricity consumption last year.