Artificial intelligence is no longer primarily a software issue; it has become an infrastructure issue. Both training and day-to-day operation of AI models require concentrated computing power, which translates into demand for electricity, grid connections, land and cooling. In the recitals of Regulation (EU) 2024/1364, the European Commission states that electricity demand from data centres is expected to reach 3.2% of total electricity consumption in the European Union (EU) by 2030, an increase of 28% compared with 2018.
Public debate tends to focus on water, as it is the most visible part of the issue. It deserves to be understood precisely, since it is surrounded by a great deal of misinformation. From a cost and emissions perspective, however, electricity is the decisive factor. The practical question is therefore not whether data centres should exist, but how they are designed and operated. The difference between a well-designed and a poorly designed facility is significant in terms of both electricity and water consumption – and under the forthcoming EU regulation, it is also set to become publicly visible, as the mandatory reported data will be used to generate an electronic label.
How much water does a data centre actually use?
In a data centre, water is not used to run the servers but to cool them. Virtually all the electricity consumed by servers is converted into heat, which must be removed from the building. Some cooling systems operate on the principle of evaporation, in which water absorbs heat. Part of the water evaporates and is released into the atmosphere. Only pure water evaporates; however, minerals remain in the circuit and gradually become concentrated. To prevent limescale from building up in the heat exchangers, part of the concentrated water must be continuously discharged to the sewer and replaced with fresh water. A smaller share is used to humidify the air in the data hall.
It is often claimed that data centres consume water and thereby deplete the world's supply. That is not how it works: the water is not lost; it simply evaporates and, on average, returns as precipitation within 8 to 10 days. The total amount of water on the planet is unaffected.
The real problem lies elsewhere. Evaporated water falls in a different place, not necessarily in the same river basin, and at the same time precipitation patterns are changing. According to the IPCC, as the climate warms, the amount of water vapour in the air increases faster than the amount of precipitation, so in many regions the same annual total arrives in fewer, heavier downpours, with longer dry spells in between. More water then runs off and less soaks into the ground, which means the same annual figure is less usable. Two local factors add to this: a data centre's water withdrawal peaks during summer heatwaves – precisely when water is scarcest – and it often draws drinking water from the public supply.
How much water a data centre uses is determined by its choice of cooling system, not by its size. Evaporative systems use the most water, while dry cooling and closed-loop liquid cooling use virtually none. This is, however, a trade-off rather than a choice between the better options: evaporative cooling uses more water and less electricity, whereas dry cooling uses less water and more electricity. And because a large share of electricity comes from water-cooled sources – typically thermal and nuclear power plants – saving electricity also saves water that never appears on the data centre site. This does not apply to wind and solar power, so the source of the electricity also matters.
What must data centre operators report?
Data centre operators report data on energy, water, temperatures and waste heat for the previous calendar year annually, by 15 May at the latest. The framework is set out in Article 12 and Annex VII of the Energy Efficiency Directive (EED) (EU) 2023/1791 and in Regulation (EU) 2024/1364, which applies to data centres with an installed information technology power demand of at least 500 kW, whether enterprise, co-location or co-hosting facilities – the latter being those where customers rent computing capacity rather than space for their own hardware. In the Czech Republic, the obligation is laid down in Section 9c of Act No. 406/2000 Coll., on Energy Management, as amended by Act No. 87/2025 Coll., effective from 1 August 2025; paragraph 1 of that Section refers to a total power input exceeding 500 kW, which under paragraph 9 includes the power input of IT equipment, so the obligation may also apply to facilities that would not meet the threshold under the Regulation. Reaching 500 kW must be notified within 2 months to the Ministry of Industry and Trade (MPO), which maintains a register of data centres. In Slovakia, reporting is done via the ReportENER platform following registration with the Slovenská inovačná a energetická agentúra (SIEA).
Four indicators are calculated from the reported values: how much electricity the entire facility consumes per kilowatt-hour delivered to the servers (PUE, Power Usage Effectiveness), how much water is used per kilowatt-hour consumed by the servers (WUE, Water Usage Effectiveness), what share of the heat produced is reused elsewhere (ERF, Energy Reuse Factor), and what share of consumption is covered by renewable energy (REF, Renewable Energy Factor).
Above a total power input of 1 MW, Section 9c(6) adds an obligation to use the waste heat, either by supplying it to a district heating system, supplying it to a customer, or consuming it directly within the operator's own energy system. If this is not feasible, it must be demonstrated by an energy assessment under Section 9a(2)(f), which is prepared during construction or when power input is increased by more than 25%, and which forms part of the supporting documentation to the construction execution documentation.
What we do at Grinity to make data centre operations greener
We help design a metering scheme that meets the requirements of the ČSN EN 50600-4 series of standards, which define efficiency indicators for data centres and specify exactly where each quantity is to be measured. We verify which of the reported indicators can actually be substantiated by existing metering and add any missing metering points. We prepare the annual submission for the European database, including defining the data centre boundaries and allocating systems shared with other operations in the building. Energy assessments under Section 9a of Act No. 406/2000 Coll. are prepared by our energy specialist, who holds an authorization granted by the MPO and is listed in the Ministry's register of energy specialists.
In addition to reporting and energy services, we also provide BREEAM and LEED certification, both of which have dedicated variants for data centres. LEED has a separate BD+C: Data Centers rating system for new facilities where at least 60% of the floor area is complete at the date of certification, and an O+M variant for existing facilities; in the latest version, LEED v5, the approaches developed for data centres are incorporated into the New Construction and Existing Buildings rating systems. BREEAM has a separate BREEAM Data Centres scheme, the current version of which dates from 2010, and outside the United Kingdom data centres are assessed under BREEAM International New Construction. For our clients, this has a practical implication: certification and mandatory reporting draw on the same data on consumption, metering and cooling, so it pays to prepare them together rather than separately.
Metering is followed by the design of energy optimization measures. These typically deliver the best return in the following order:
- Install sub-metering. Until server consumption is metered separately, the facility's efficiency is an estimate rather than a calculation. Metering at uninterruptible power supplies and at rack power distribution units is both a mandatory input for reporting and the first basis for any further decision.
- Separate cold and hot air in the data hall. In a typical data hall, the cold air supplied to the servers mixes with the hot air leaving them. The cooling system compensates by producing air that is colder than necessary. Containing the aisle between rows of racks, fitting blanking panels in empty rack positions, and sealing floor penetrations separates the two airflows. This is the measure with the best cost-to-benefit ratio, as it requires no intervention in the cooling source.
- Raise the supply air temperature to the servers. Data halls are often cooled to lower temperatures than servers actually require, usually out of caution and due to legacy settings. This opens up significant scope for free cooling using dry coolers or direct free cooling. Every additional degree means more hours per year when outdoor air alone is sufficient for cooling, eliminating the need for compressor-based or evaporative cooling and saving both electricity and water. The set temperature is also a reported value in its own right. How far it can be raised depends on the operating conditions of the specific hardware, so this is not a desk-based measure but the outcome of an assessment of the data hall.
- Optimize evaporative cooling. In facilities that already use evaporative cooling, water consumption can be reduced without replacing the technology by adjusting the outdoor temperature at which the evaporative stage is activated and how often the water in the circuit is replaced. Both are typically set conservatively by the supplier and never revisited.
- Reuse waste heat. Heat from servers can be fed into a district heating system, a neighboring building or the operator's own operations. Another attractive technical solution is heat loops with decentralized water-to-water heat pumps located in surrounding buildings, which use waste heat from data centres to provide space heating or domestic hot water. For facilities above 1 MW, this is not an option but a legal obligation – and the earlier it is addressed, the lower the cost, as it can be factored into the design of the distribution systems from the outset.
- Address electricity procurement. The share of renewable energy is reported and can be increased through on-site generation, a direct supply contract with a specific generation source (Power Purchase Agreement, PPA), or the purchase of guarantees of origin. Each of these routes is subject to different conditions for counting towards reporting, and it is advisable to understand them before signing a contract.
Next Step
The European Commission is preparing a regulation that will use the reported data to generate a publicly available electronic label with energy and water efficiency classes; according to the draft published on 2 July 2026, the label is to be generated automatically from 15 August 2027. Get in touch with us – we will be happy to discuss, without obligation, the scope of an assessment of your data centre and propose a metering scheme appropriate to its size and type of operation.