"If we do not make sure that these big power consumers are indeed in line with our overall objectives… then they will risk undermining our ability to live up to our own targets," the EU's energy chief, Dan Jørgensen, said in an interview with POLITICO.

According to the Commission's figures, Europe’s data centers used 20.7 terawatt-hours of electricity — about as much electricity as the entire nation of Croatia consumes — and more than 8 million cubic meters of water in 2025. That's a 26% increase in electricity use and 52% in water use from 2024.

But those numbers do not fully account for the sector's actual use, as the totals are the result of incomplete data collected by the Commission. The data has only been published in aggregate, following a 2024 law that banned Brussels and EU capitals from disclosing "all information and key performance indicators for individual data centers" amid lobbying from tech giants, which cited commercial interests.

Diego Solier, a conservative member of the European Parliament working on the EU's legislative push to boost the bloc's digital capacity, said Europe's data center expansion must be accompanied by reliable information for citizens and policymakers about how much energy and water is being used.

"Transparency should be the starting point," said Solier, who didn't comment on the complaint itself, which wasn't yet public. "At the same time, transparency must be proportionate, and should not require companies to disclose genuinely commercially sensitive information."

Right to know

Lighthouse Reports says the Commission "holds the primary responsibility [of] denying public knowledge of the effects of Europe's massive data center build-out," by allowing operators to keep details of their consumption under wraps and dodge scrutiny in the process — in breach of the Aarhus Convention, which the EU has been a party to since 2005.