Exploring Liquid Cooling Solutions for Data Centres

As data centres grow in size, density, and complexity, managing heat becomes increasingly challenging. Traditional air cooling methods are starting to show their limitations, especially with high-performance computing (HPC), artificial intelligence (AI) workloads, and dense server architectures.

Enter liquid cooling—a technology that has long been used in niche areas like supercomputing and is now gaining momentum in mainstream data centre operations. But is liquid cooling right for every data centre?

What Is Liquid Cooling?

Liquid cooling involves using fluids—typically water or specially formulated coolants—to remove heat from computer components. It comes in various forms, including:

• Direct-to-chip Cooling: Coolant is pumped through cold plates that sit directly on hot components like CPUs and GPUs.
• Immersion Cooling: Servers are fully or partially submerged in a non-conductive liquid.
• Rear-door Heat Exchangers: Heat is removed via a liquid-cooled door on the back of a rack.

Each approach differs in complexity, cost, and efficiency, but they all share the same goal: to move heat more effectively than air-based systems.

For more information see:
https://www.digitalrealty.co.uk/resources/articles/future-of-data-center-cooling

The Advantages of Liquid Cooling in Data Centres

There are several positives from using liquid cooling in data centres. These include superior cooling efficiency, energy savings, higher density racks and space efficiency, quieter operation and potential for heat reuse.

Superior Cooling Efficiency

The most obvious advantage of liquid cooling is its efficiency. Water can carry away heat up to 4,000 times more effectively than air. This means:

• Faster removal of heat from components
• Lower operating temperatures
• Reduced risk of thermal throttling

Table 1: Power Usage Effectiveness (PUE) Comparison

Power Usage Effectiveness (PUE) is a key metric in data centre energy efficiency. The closer to 1.0, the better. Liquid cooling systems significantly lower PUE by reducing reliance on traditional HVAC and fans. For workloads requiring maximum performance—like AI training, scientific simulations, or real-time data analytics, this is a game changer.

Energy Savings

Air cooling systems often rely on powerful fans and HVAC systems to circulate chilled air. These consume a significant portion of a data centre’s total energy—sometimes up to 40%.

Liquid cooling can reduce or even eliminate the need for traditional air conditioning. By operating at higher inlet temperatures or leveraging outside ambient temperatures for heat rejection, data centres can significantly improve their Power Usage Effectiveness (PUE), sometimes achieving values close to 1.05.

Higher Density and Space Efficiency

Liquid cooling enables tighter hardware packing without the risk of overheating. This is particularly valuable for:

• Colocation facilities with limited space
• Edge computing installations
• Modular or containerised data centres

By managing heat more effectively, liquid-cooled racks can support higher power densities—10 kW, 20 kW, or even 100 kW per rack.

Table 2: Power Density by Cooling Technology (kW per rack)

Liquid cooling supports much higher rack power densities, enabling more computational power per square foot—a key factor in modern, space-constrained facilities.

Quieter Operation

Air-cooled data centres require high-speed fans, which can be noisy and generate vibrations. Liquid cooling systems are typically much quieter, creating a more pleasant environment for technicians and reducing noise pollution.

Potential for Heat Reuse

Since liquid cooling captures heat more directly, it opens up possibilities for heat reuse. Some innovative data centres have started using their waste heat to warm nearby buildings, greenhouses, or swimming pools—transforming a liability into a sustainable asset.

What is The Downside of Using Liquid Cooling in Data Centres

Despite its benefits, liquid cooling also comes with significant challenges. These factors must be considered before implementation and include higher upfront costs, system complexity and maintenance costs, vendor lock-in and compatibility issues, the risks of downtime and deployment limitations in the type and size of data centres that liquid cooling is more suited to.

Higher Upfront Costs

Installing a liquid cooling system typically involves a higher capital expenditure (CapEx) compared to traditional air cooling. Costs come from:

• Specialised hardware (cold plates, pumps, tubing)
• Retrofitting existing infrastructure
• Backup and safety systems

Even though operational savings (OpEx) may offset these costs over time, the initial investment can be a barrier, especially for small or mid-sized operators.

Complexity and Maintenance

Liquid systems are mechanically and chemically more complex than air-based solutions. They require:

• Leak detection and containment systems
• Coolant quality monitoring
• Redundant plumbing and failover systems

Leaks, although rare in well-designed systems, can be catastrophic if not contained. Maintenance also requires specialised training and often longer service windows.

Vendor Lock-in and Compatibility Issues

Currently, liquid cooling is less standardised than air cooling. Many solutions are proprietary, meaning:

• Difficult integration with off-the-shelf servers
• Limited flexibility in vendor selection
• Potential for lock-in with a single technology provider

This can complicate procurement, upgrades, and long-term planning.

Risk of Downtime

Although robust systems are built with reliability in mind, the introduction of fluids into an IT environment adds new potential points of failure. Malfunctions in pumps, valves, or heat exchangers could lead to downtime if not properly managed. This makes environmental monitoring in data centres and redundancy especially critical in liquid-cooled data centres. See our case study on using AKCP devices to monitor an advanced immersion cooling POD.

Deployment Limitations

Liquid cooling makes the most sense in environments with high thermal output. For lower-density data centres, the return on investment might not be as strong. Additionally, edge locations or older facilities may lack the infrastructure (e.g. water supply, drainage, chilled water loops) to support a liquid cooling deployment without extensive upgrades.

Who Should Consider Liquid Cooling?

Liquid cooling is not a one-size-fits-all solution, but it’s ideal for certain scenarios:

• High-density computing: Environments with 20 kW+ racks, AI/ML workloads, or GPU farms
• Space-constrained sites: Urban data centres, edge facilities, and micro data centres
• Sustainability-focused operators: Organisations aiming for ultra-low PUE or heat reuse
• Innovation-driven businesses: Enterprises looking to stay ahead of the performance curve

For hyperscalers and companies operating at the cutting edge, liquid cooling is quickly becoming a necessity rather than an option.

Summary

Liquid cooling represents a transformative shift in data centre design and operation. Its benefits—superior thermal efficiency, energy savings, and support for high-density computing—make it an attractive alternative to traditional air cooling. However, the higher initial costs, added complexity, and infrastructure requirements mean it’s not suitable for everyone.

As the industry continues to evolve and computing demands escalate, liquid cooling will likely play a central role in the next generation of data centres. Whether you’re planning a new facility or upgrading an existing one, understanding the pros and cons of liquid cooling is essential for making an informed decision.

For more information on the Airsys intelligent cooling solutions we supply for data centres, please contact our Projects Team.