Liam Jackson, Senior Director at Red Helix, explains how adopting liquid cooling solutions can drive cost and energy efficiencies.

In recent years, energy efficiency has emerged as a pivotal concern for businesses, driven not only by the need to reduce operating costs, but also by the imperative to meet tightening sustainability goals and uphold corporate reputations. This is particularly true for data centres, which currently consume 2.5% of the UK’s total electricity. As data usage continues to rise, so will the energy used by data centres, with estimates suggesting they will consume just under 6% of the UK’s electricity by 2030.

Interestingly, only 10% of this energy consumption is used for heavy computational work. The remainder powers the facility’s continuous operation, ensuring they are running 24/7 to satisfy the demand for instant access to information. A considerable portion of this, roughly 40% of the total energy usage, is spent on cooling equipment to avoid any detrimental overheating.  Consequently, enhancing efficiency in this area can yield substantial benefits for data centre operators.

It is also worth noting that the EU Code of Conduct on Data Centre Energy Efficiency has been established in an effort to reduce the environmental, economic, and supply security impacts of data centre energy consumption. While this is a voluntary initiative, from 15 March 2024, any data centre with an IT power demand of 500 kW or above will be required to report on their energy usage. There are also several countries that have mandated their own targets based on this, as well as additional benefits through the EU Taxonomy for those who can demonstrate environmentally sustainable activities.

Though this is not currently something that the UK is part of, following the trend of other EU legislative actions, it is reasonable to expect a similar initiative to be produced in the near future.

This is where liquid cooling comes into the equation, serving as an energy-efficient, cost-saving alternative to traditional cooling methods, providing data centre operators – and any other company using an IT/server room – with an effective way to reduce power consumption.

The problem with conventional air cooling

Typically, data centres have relied on HVAC systems to cool their equipment, using a cycle of refrigerant compression and decompression to create a thermal exchange mechanism. This cooling is a critical process, as the immense heat generated by servers and computer systems can quickly lead to hardware malfunctions if not adequately managed – as evidenced by the Google server outages during the 2022 heatwave.

The issue is that these HVAC systems aren’t very efficient. They depend on electric pumps to facilitate the compression process, which are constantly running, translating into substantial energy consumption. 

Air cooling is also not particularly well targeted, as it is difficult to evenly distribute cold air across the data centre. While many data centre operators have addressed this through containment strategies, reducing the amount of space that requires cooling by isolating different areas of the room does not totally fix the problem. The energy usage remains high, smaller spaces means less computing capacity, and the system is also highly susceptible to environmental factors.

Owing to these challenges, and the consistent rise in data consumption, industry-wide Power Usage Effectiveness (PUE) improvements have halted. The Uptime Institute’s most recent Annual Global Data Center survey reports an average PUE of 1.58, which is the same as it was in 2018. 

As we pivot towards an era dominated by compute-intensive technologies, such as AI, the demand on data centres will only intensify. They will need more processing power, leading to increased heat generation and, as a result, a requirement for more efficient and effective cooling solutions that can reduce operational costs and help to mitigate the environmental concerns surrounding high energy usage.

How liquid cooling can help 

Liquid cooling leverages the higher thermal transfer properties of water to cool equipment. Water has a higher heat capacity than air, meaning it can absorb more heat before its own temperature increases, making it a more effective medium for the job.

This process involves cool water being piped in directly through a heat exchanger behind or adjacent to the IT equipment to draw away the heat. Then, once warmed, the liquid is circulated out to a cooling device. This doesn’t necessarily need to be a device that draws large amounts of power, but instead can be a multitude of small heat exchangers, such as cooling towers or fans, or can even be achieved by running the pipes through a nearby body of water. After it has been cooled, the water is once again piped through, and the cooled air from the heat exchanger can be returned to the data centre to help maintain an ambient air temperature.

While fans can be used to help cool the liquid, in many cases, this isn’t necessary – particularly in the Northern Hemisphere. The ideal temperature for server rooms is between 18 – 27°C, which means that, for a significant part of the year, the outside air is a sufficient temperature. In the UK, for example, the average temperatures over the past 20 years haven’t risen above the limit of 27°C – removing the need to cool the liquid almost entirely.

Reaping the benefits

There are many reasons for making the switch to liquid cooling. Firstly, as the process is more efficient, it drastically reduces the energy used to cool equipment. This results in significant cost savings and a reduced environmental impact, helping data centres and other IT-intensive businesses align with eco-friendly practices and manage operational expenditure.

Liquid cooling systems are also far more compact than their HVAC counterparts, freeing up valuable space that can be repurposed for additional servers or storage. This provides both a logistical and a strategic benefit, enhancing the overall capacity and scalability of data centre operations.

Precision in temperature control is another area for improvement. By directly targeting specific areas, liquid cooling ensures that each component is operating within its ideal temperature range – extending the service life and improving the performance of equipment.

There is also the potential to integrate the heat exchange with nearby facilities. The warm water from the cooling system can be channelled to heat adjacent buildings, or even used to heat swimming pools; addressing the challenge of heat disposal while contributing positively to the surrounding community.

A cooling solution for the compute-intensive future

The demand for energy-efficient solutions in data centres is rising, and liquid cooling marks a significant leap towards addressing the dual challenge of escalating data demands and tighter ESG commitments. 

Not only does liquid cooling facilitate the operation of more equipment, as well as leaving valuable floor space for additional racks, but it can also greatly reduce energy usage and costs. In doing so, it provides data centre/colocation operators, and any other companies that use air conditioning for server cabinet cooling, with an effective solution to keeping up with the burgeoning demands of compute-intensive technologies, while significantly reducing their carbon footprint.

Embracing liquid cooling represents more than just a practical choice for data centres; it is a vital step towards a more energy-conscious and sustainable future.