When to Move from Air Cooling to Liquid Cooling for Your Data Center

The Growing Cooling Challenge

The demands on data centers are reaching new heights. Power densities now commonly exceed 30 kW per rack and the increased thermal design power (TDP) of modern CPUs and GPUs only intensifies the cooling burden.

While air cooling has long been the go-to for its simplicity and affordability, its limitations become evident as energy use and costs rise. IDC forecasts that AI-driven data center capacity will grow at a 40.5% compound annual growth rate (CAGR) by 2027¹, and global data center electricity consumption is set to more than double from 2023 to 2028².

As power demands mount, energy efficiency is a growing priority, and effective air cooling requires substantial space-posing a challenge for data centers operating in tight quarters.

Can Air Cooling Keep Up?

In many standard workloads with lower densities (under ~ 10-15 kW per rack), air cooling remains a viable solution, particularly given Dell's innovations in airflow management and high-efficiency fans. These improvements push the boundaries of air-cooled environments, keeping costs reasonable for moderate demands.

However, as power densities rise, air cooling brings certain drawbacks, including increasing cooling costs, performance risks from thermal throttling and limited scalability. Cooling-related outages can also become more frequent, driving up maintenance needs and risking operational downtime.

For data centers expecting growth or facing mounting cooling costs, these challenges may signal a need to consider a more efficient cooling approach.

The Advantages of Liquid Cooling

Liquid cooling is rapidly gaining favor in high-density data centers, harnessing liquid's superior thermal conductivity to manage heat more effectively.

Compared to air cooling, liquid cooling delivers up to 40% in energy savings; a recent National Renewable Energy Laboratory (NREL) report shows it can achieve a Power Usage Effectiveness (PUE) as low as 1.05, far more efficient than the typical 1.5-2.0 PUE of air-cooled systems³.

The benefits extend beyond energy savings: liquid cooling also supports racks with densities over 20 kW, where air cooling starts to falter. Dell's Integrated Rack Scalable Systems (IRSS) can handle densities as high as 264 kW, with the potential to go even higher.

Liquid cooling also saves space by enabling higher compute density per rack, freeing up valuable real estate within the data center. Plus, with reduced reliance on fans, liquid cooling brings quieter operations. Closed-loop systems that recycle cooling water add a further edge, aligning with sustainability goals by reducing waste and lowering secondary cooling demands.

When Is the Right Time to Transition?

The decision to switch to liquid cooling often becomes clear when certain signs appear. Power density is a key factor; when densities surpass 15-20 kW per rack, air cooling struggles to keep temperatures in check without major upgrades.

A rising PUE can also indicate an inefficient air-cooling setup, making it both costly and challenging to maintain. Escalating energy prices further intensify the need for more efficient cooling, especially as sustainability commitments grow. For data centers facing space constraints, liquid cooling also enables more compute power in a smaller footprint, reducing the need for physical expansion.

Switching from air to liquid cooling doesn't have to be an all-or-nothing move. Many data centers take an incremental approach.

One approach that can reduce energy consumption, increase efficiency and support denser workloads is a Liquid-to-Air Cooling (LAC) CDU. LAC CDUs use air as a heat transfer medium and don't require water pipes to be connected to the data center. It provides organizations with flexibility to adapt their cooling strategy as the needs of the data center evolve.

Another hybrid solution is to retrofit air-cooled setups with Rear Door Heat Exchangers (RDHx). Organizations can continue to use air-cooled servers but supplement them with liquid cooling via the RDHx. For even higher cooling capacity, a Liquid-to-Liquid CDU (LL CDU) leverages the facility's water infrastructure to cool the servers and equipment. It is one of the most efficient and future-proof methods of cooling dense workloads.

As organizations embark on this journey, they are not alone. Our team of experts is equipped to assist in the planning, design and implementation of a tailored cooling strategy to ensure a successful and stress-free transition to liquid cooling in the data center.

A Forward-Looking Data Center Solution

For data centers aiming to balance performance, scalability and cost, liquid cooling provides a compelling answer to the challenges of high-density, high-performance environments. While air cooling still works for many, its limitations are apparent as power demands grow.

Liquid cooling delivers superior energy efficiency, supports greater scalability, and aligns with sustainability goals, offering a forward-looking solution that equips data centers to meet the needs of tomorrow's IT infrastructure. By assessing current and future requirements and planning a phased transition, organizations can make a seamless move to liquid cooling and be ready for the future of data center operations.

Related Smart Power and Cooling blogs:

The Power of Direct Liquid Cooling: A Solution Built for Your Business Needs

Unleashing the Future: Dell's Journey in Liquid Cooling Innovation

Dell PowerEdge Empowers AI Factories with Scalable Systems

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