Liquid Cooling for Data Centers: Options and performance

As data center requirements continue to evolve—driven by AI, HPC and increasing rack densities—the need for reliable, energy-efficient cooling systems has become critical. In this context, liquid cooling for data centers is emerging as a key alternative to traditional air-based and conventional water-cooled solutions.

Cooling is no longer a secondary infrastructure decision. It directly impacts IT reliability, operational costs, energy efficiency, water usage effectiveness (WUE) and long-term scalability. Choosing the right cooling strategy can determine whether a data center operates efficiently—or struggles under thermal and energy constraints.

While hyperscalers may locate facilities in cold climates, most operators must design data centers in hot or mixed climates, often close to urban centers. Projects such as ARANER’s work at the Al-Ashghal Data Center demonstrate how advanced cooling strategies can achieve outstanding performance even in regions where high ambient temperatures are the norm.

This is where liquid cooling technologies play a decisive role.

What is liquid cooling for data centers

Liquid cooling for data centers refers to a group of cooling technologies that use liquids—rather than air—as the primary medium to remove heat from IT equipment.

The fundamental principle is simple:
liquids transfer heat far more efficiently than air.

Traditional air-cooled data centers rely on Computer Room Air Conditioning (CRAC) or Computer Room Air Handler (CRAH) units, where hot air is extracted, cooled and recirculated. While effective at low power densities, air cooling becomes inefficient as rack densities increase.

Liquid-cooled systems, by contrast, bring the cooling medium closer to the heat source—dramatically improving heat transfer and reducing energy consumption.

How Does Liquid Cooling Differ from Air Cooling?

The key difference lies in thermal conductivity and proximity to the heat source:

• Air cooling removes heat indirectly via room airflow

• Liquid cooling removes heat directly at rack, server or component level

This allows liquid cooling systems to:

• Handle higher power densities

• Reduce fan energy

• Improve PUE and WUE

• Enable more compact data center designs

As power densities rise, air cooling alone becomes a limiting factor.

What are the main types of Liquid Cooling for Data Centers?

Liquid cooling is not a single technology. There are several configurations, each suited to different use cases.

1. Direct Liquid Cooling (Water Cooling)

In direct liquid cooling, water (or water-based fluids) circulates through closed, watertight loops that remove heat from servers via cold plates or rear-door heat exchangers.

Because water cannot come into direct contact with electronics, heat transfer is indirect.

Typical characteristics

• Uses pumps, piping and heat exchangers

• Compatible with existing data center layouts

• Often combined with CRAH units

• Improves efficiency compared to air cooling

This approach is commonly referred to as data center water cooling.

2. Liquid Immersion Cooling

Liquid immersion cooling represents the most advanced form of liquid cooling.

In this configuration:

• IT equipment is submerged in a dielectric (non-conductive) fluid

• Heat is transferred directly from components to the liquid

• Heat is removed via a heat exchanger

Why immersion cooling stands out

• Extremely high heat transfer efficiency

• Ideal for very high-density racks

• Minimal airflow requirements

• Reduced mechanical complexity

Immersion cooling can be applied at:

• Component level

• Server level

• Full rack or tank level

It is increasingly adopted in AI, HPC and GPU-intensive workloads.

Why is Liquid Cooling becoming Critical for Data Center Efficiency?

Modern data centers face multiple converging pressures:

• Rising rack densities

• AI and HPC workloads

• Higher electricity costs

• Sustainability and water constraints

Cooling strategy is one of the few variables operators can actively optimize.

As a general guideline:

• Above ~15 kW per rack, liquid cooling becomes increasingly attractive

• Above 30–40 kW per rack, air cooling alone is no longer viable

Liquid immersion cooling, in particular, enables data centers to scale without exponential increases in energy or water consumption.

Design Considerations for Liquid Cooling in Data Centers

Liquid cooling systems must be engineered holistically. Key factors include:

• Climate and geographic location

• Local water availability and regulations

• IT load profiles

• Rack density roadmap

• Redundancy and resilience requirements

Industry guidance from ASHRAE plays a central role in defining safe and efficient operating conditions.

ASHRAE Thermal Guidelines recommend:

• Typical inlet temperatures between 18°C and 27°C

• Defined envelopes for reliability, functionality and failure conditions

Additional standards relevant to liquid-cooled data centers include:

• ISO 14644 (airborne particulate control)

• ANSI/ASHRAE Standard 127 (data center air quality)

• ANSI/ISA-71.04 (gaseous contamination levels)

What Are the Main Advantages of Liquid Cooling for Data Centers?

1. Superior Energy Efficiency

Liquids can transfer heat hundreds of times more efficiently than air, dramatically reducing cooling energy demand.

2. Lower Operating Costs

Liquid immersion systems have demonstrated significant reductions in cooling electricity consumption, especially at high power densities.

3. High Reliability

Stable thermal conditions protect sensitive IT equipment and support demanding HPC and AI workloads.

4. Targeted Cooling

Cooling can be applied exactly where heat is generated, avoiding over-cooling of entire rooms.

5. Simplified Infrastructure

Reduced reliance on raised floors, large air plenums and extensive ducting.

6. Flexible and Scalable

Liquid cooling supports future growth without major redesigns.

7. Reduced Maintenance Risk

Immersion cooling eliminates concerns such as corrosion, condensation and water leaks associated with traditional water systems.

How to Choose the Right Liquid Cooling Technology for a Data Center

There is no one-size-fits-all solution.

Choosing the right liquid cooling approach depends on:

• Power density today and tomorrow

• New build vs retrofit

• Water usage strategy

• Sustainability targets

• Capital vs operational cost balance

Cooling engineers must evaluate the entire energy ecosystem of the data center—not just the cooling equipment itself.

At Araner, we commit to designing data center cooling technologies that match each project’s needs and achieve the maximum sustainability and efficiency. We thus design and implement liquid cooling options for data centers, helping companies generate optimized data center environments with a flexible, plug-and-play approach that is also able to comply with the industry’s highest standards. 

Learn more about cutting-edge data cooling and liquid cooling options and how we work to develop the project each operator needs. Download our free Data Center Reference Ebook or read more about our work in the Al-Ashghal Case Study, a data center cooling solution based on a naturally-stratified water storage tank and a state-of-the-art Thermal Energy Storage (TES) system. You can also get in touch with us to speak directly to our team and discover how we can push data center cooling efficiencies to the maximum.