Data center cooling: optimising water consumption with ultrasonic flow meters

The exponential growth of data centers, driven by the cloud, artificial intelligence (AI), and big data, is leading to a continuous increase in power densities and cooling requirements. In this context, controlling heat transfer fluid flow rates is becoming strategic. This is especially true as liquid cooling systems are increasingly used in most data centers around the world.

Ultrasonic flow meters are now establishing themselves as a reliable, non-intrusive measurement solution for optimizing data center cooling systems, whether they use chilled water or direct liquid cooling (DLC).


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How do data center cooling systems work?

The primary role of a data center cooling system is to extract the heat generated by IT equipment (servers, network racks, storage) in order to maintain safe and stable operating conditions. The principle is simple: every kilowatt consumed by IT is converted almost entirely into heat, which must be continuously removed.

Aerial view of industrial cooling systems installed on the roof of a large technical complex

Chilled water cooling and hydraulic loops

To improve performance, many data centers use chilled water hydraulic systems. Heat is transferred from the air to the water via heat exchangers and then removed using:

These hydraulic architectures enable better thermal control, improved energy efficiency, and optimized large-scale cooling distribution.

Rows of servers in computer room with blue lighting and cold aisle containment
Illustrated server room to explain how cooling systems work in data centers.
Liquid cooling system with green pipes connected to rack servers

Liquid cooling: meeting high densities

With the rise of AI, high-performance computing (HPC), and high-density racks, liquid cooling is becoming essential. Two main approaches coexist:

  • Direct Liquid Cooling (DLC): a fluid circulates directly in contact with the hottest components (processor (CPU), graphics processor (GPU)) via cold plates.
  • Immersion cooling: servers are immersed in a dielectric fluid that absorbs heat very efficiently.

In these architectures, controlling fluid flow rates is essential to ensure consistent thermal performance and equipment safety.


Data center cooling systems in figures

Industrial cooling units and piping installed on the roof of a data center

The figures illustrate the extent to which cooling is an energy, economic, and environmental issue for modern data centers.

  • 40% of a data center's electricity consumption is dedicated to cooling and air conditioning server rooms.
  • Poor hydraulic control can lead to energy over consumption of up to 10 to 20%, due to excessive or poorly balanced flow rates.
  • Liquid cooling can extract up to 3 to 5 times more heat than air cooling, for an equivalent surface area.
  • In some regions, a data center's water consumption can reach several hundred thousand cubic meters per year, making the measurement and optimization of hydraulic circuits essential.

These figures clearly show that the performance of a data center no longer depends solely on servers, but also on measurement accuracy, throughput control, and cooling system optimization.


The energy consumption challenges of cooling a data center

Two engineers analyze data on screens in front of a server room in the background.

A modern data center converts almost all of the electrical energy it consumes into waste heat. However, data centers must balance very dense workloads with sustainability goals.

Cooling systems must therefore:

  • Ensure maximum availability (avoid overheating and downtime),
  • Optimizing energy efficiency,
  • Limit water consumption,
  • Adapting to increasingly complex architectures (multiple hydraulic loops, redundancy, modularity).

In this context, accurate and continuous flow measurement is essential for effective control of the installations.

Network of industrial pipes connecting cooling units on the roof of a data center
Roof cooling infrastructure with cooling units and hydraulic network for site thermal management.

Ultrasonic flow meters in data center cooling systems

Ultrasonic flow meters have many applications in data centers, wherever control of hydraulic flows is essential to the performance, safety, and energy efficiency of facilities.

Flow meter installed on a chilled water pipe with wall-mounted electronic box

Measuring chilled water flow rates in cooling loops

In chilled water cooling systems, ultrasonic flow meters are used to:

  • Monitor the flow rates at the outlet of cooling units,
  • Monitor primary and secondary loops,
  • Check the hydraulic balance between the different IT rooms.

They ensure even distribution of cold air and prevent energy waste caused by excessive flow rates.

Diagram of an industrial cooling circuit with heat exchanger, pump, reservoir, and cooling unit

Monitoring of liquid cooling circuits (LCC)

With the development of liquid cooling circuits, measurement accuracy is essential. Ultrasonic flow meters are used for:

  • Control the flow rates supplying the cold plates of the CPU and GPU processors.
  • Secure cooling for high-density racks,
  • Ensure consistent thermal performance, even with IT load variations.

 

Aerial view of a data center with cooling towers and steam plumes

Control of coolant distribution units (CDU)

Cooling units provide the interface between IT cooling loops and building hydraulic circuits. Ultrasonic flow meters play a key role in this regard for:

  • Accurately measure incoming and outgoing flow rates,
  • Detect hydraulic anomalies,
  • Optimize the overall efficiency of liquid cooling systems.

 

Rows of servers installed outdoors in the middle of dense vegetation

Energy optimization and monitoring of the energy performance indicator (EPI)

By providing reliable and continuous data, ultrasonic flow meters directly contribute to:

 

Two technicians analyze data on a laptop in the server room.

Supervision, maintenance, and sustainability

Integrated into energy management systems, ultrasonic flow meters enable:

  • Real-time monitoring of facilities,
  • Early detection of leaks or spills,
  • The implementation of predictive maintenance strategies,
  • Accurate monitoring of water consumption.

Thanks to their versatility, ultrasonic flow meters are becoming key instruments in supporting the evolution of data centers toward more efficient, energy-efficient, and resilient infrastructures .


The advantages of ultrasonic flow meters for data center cooling

Measurement performance tailored to critical data center infrastructure

Ultrasonic flow meters with displays and flanged sensors for industrial flow measurement

Ultrasonic flow meters have features that are particularly well suited to the constraints of data center cooling systems, where reliability, accuracy, and continuity of service are key requirements.

Their main advantages for cooling data centers are as follows:

  • Non-intrusive measurement with no pressure loss: installation without obstructing the pipe, preservation of hydraulic balance, and no risk of leakage.
  • High reliability and low maintenance: no moving parts, excellent measurement stability over time, and maximum system availability.
  • Measurement accuracy: fine adjustment of chilled water and coolant flow rates according to IT load, limitation of overcooling, and optimization of energy consumption.
  • Compatibility with modern architectures: integration into chilled water circuits, direct liquid cooling (DLC) circuits, CDU circuits, and existing networks, including those with large diameters.
  • Integration with supervision systems: connection to energy management systems for real-time control, anomaly detection, and predictive maintenance.

Thanks to this set of advantages, ultrasonic flow meters are an essential tool for securing cooling systems and sustainably improving the energy performance of data centers.

Rows of servers in a data center with blue lighting and a reflective central aisle
Illustration of a modern data center.

FAQ – Ultrasonic flow meters and data center cooling

Why is flow measurement essential in a data center?

Flow measurement ensures that the amount of coolant circulating in the hydraulic loops is appropriate for the actual IT load. Accurate measurement prevents the risk of overheating, limits overcooling, and directly contributes to energy optimization and PUE reduction.

Why choose an ultrasonic flow meter over another type of flow meter?

Ultrasonic flow meters are non-intrusive, have no moving parts, and cause no pressure loss. They offer excellent reliability, require little maintenance, and are particularly well suited to data center infrastructure, where service continuity is essential.

Are ultrasonic flow meters compatible with liquid cooling (LLC)?

Yes. Ultrasonic flow meters are perfectly suited to direct liquid cooling (DLC) circuits, particularly for controlling the flow rates feeding the cold plates of CPU and GPU processors, as well as for controlling CDUs.

Can an ultrasonic flow meter be installed on an existing network?

Yes. Thanks to their non-intrusive technology, ultrasonic flow meters can be installed on existing networks, including large-diameter pipes, without major service interruptions or extensive modifications to the installations.

How do ultrasonic flow meters contribute to energy efficiency in data centers?

By providing reliable, real-time flow data, ultrasonic flow meters optimize pump operation, balance hydraulic circuits, and reduce energy consumption related to cooling.

What impact do cooling systems have on the energy efficiency and environmental footprint of data centers?

Cooling systems play a decisive role in the environmental impact of data centers. A significant portion of the energy consumed is related to cooling and thermal management of the facilities. Liquid cooling and free cooling solutions, when properly designed and implemented, can significantly reduce overall energy consumption.

The energy efficiency of a data center is generally assessed using PUE (Power Usage Effectiveness), which measures the ratio between total energy consumed and energy dedicated to IT and cooling equipment. Inadequate thermal management can significantly degrade this ratio, leading to overconsumption of energy, increased water demand, and major repercussions on the reliability of equipment and infrastructure.

Improving environmental performance requires more energy-efficient cooling solutions, better control of temperatures, flow rates, and resources, as well as the adoption of methods, tools, and innovations adapted to the constraints of data centers. These elements are essential for supporting corporate decision-making and designing more sustainable infrastructures with better indicators such as PUE and CUE.


Selecting and optimizing data center cooling solutions: a comprehensive approach

The issue of data center cooling is no longer limited to choosing a single technology. It requires a comprehensive approach that integrates energy, thermal processing, various cooling options, and environmental constraints. Heat production, temperature management, infrastructure layout (floor, building), use of outside air via free cooling, and dew point control are all key factors in designing high-performance systems.

To guide decision-making, companies must rely on tools, proven methods, and expert partners capable of analyzing energy demand, operating data, and material and energy flows. This approach enables continuous performance improvement, better resource management, and the implementation of more energy-efficient cooling solutions.

In this context, ultrasonic flow meters are key allies. Non-intrusive, reliable, and accurate, they support controlled thermal management, reduce the risks associated with poor regulation, and directly contribute to reducing the environmental impact of data centers.

Faced with the challenges of energy management, heat production, and environmental performance, liquid cooling and free cooling solutions can reduce the overall energy consumption of data centers. To design, implement, and optimize these solutions— from decision-making to technical implementation —companies can rely on the expertise of Fuji Electric teams, who can offer methods, tools, and innovations tailored to each data center environment.