Is chilled water cooling the right technology for the future data centres?

Data centres are becoming increasingly important to all aspects of modern life. Driven by a rise in penetration of high-end cloud computing in enterprises, the rapid digitalisation of all industries, the new normal of remote work, the growing use of Over-The-Top services and much more, it is predicted that the data centre services market will continue to grow. It is predicted that the data centre services market will continue to grow at a rapid rate.

“Like many businesses in all industries, data centre providers are balancing their growth plans with a commitment to meeting energy efficiency and carbon neutrality targets,” Andrea Moscheni, thermal management product application manager for Vertiv says. “Major data centre operators have signed The Climate Neutral Data Centre Pact, and many more are moving in the same direction; the industry in Europe has committed to climate neutrality by 2030, ensuring that sustainability is now a key element of any business process.  And while there is no one ‘silver bullet’ solution to becoming sustainable, a lot can be mitigated by the use of chilled-water cooling systems.

“This technology provides a viable way for data centre providers and managers to not only support their growth cost-effectively and with minimal disruption, but also reduce their carbon footprint by cutting both direct emissions and indirect emissions.”  

Addressing cooling challenges

Traditional refrigerants are already being replaced by HFO (hydrofluoro-olefin) alternatives. However, most of these new, low GWP (global warming potential) refrigerants are classified by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) as mildly flammable therefore requiring a new design for the cooling system, potentially impacting the broader data centre design.    

“We know that chilled water systems offer an excellent solution to this issue as the refrigerant is contained within chiller units and, in most applications, these are installed outside of the data centre, thus simplifying the use of flammable fluids,” Moscheni continues. “Chilled water systems are one of the first cooling technologies to apply low GWP refrigerants in data centre applications and therefore are an example of a valid alternative for reducing direct environmental impacts.  Equipped with inverter-driven screw compressors or oil-free centrifugal compressors, chillers are now available to drastically cut down electricity consumption compared to the previous technology available.

“Chilled water solutions also play a vital role in the reduction of the indirect emissions (cutting energy consumption).  In recent years, they have applied a range of cooling system efficiency improvements that allow a reduction of electricity usage, saving costs as well as being less harmful to the environment.”

Tech innovation continues at pace

The good news is that developments in this arena are happening all the time, delivering more efficiencies and greater benefits to providers. For example, over the past few years, ASHRAE has increased the recommended operating temperature of data centre equipment up to 27OC, allowing subsequent increases to the water temperatures within chilled water systems and enabling an extended use of free cooling chillers, even in countries or climates where free cooling was not previously feasible.

“Adiabatic technology can also improve the efficiency of a chilled-water system,” Moscheni continues. “In these solutions, the ambient air is cooled down by passing through wet pads. The air is then delivered at a lower temperature, achieving a higher free cooling capacity of the chiller and a more efficient operation of the compressor. The core of this solution is the onboard controller of the unit; it enables the use of water whenever strictly needed, according either to redundancy, efficiency, or cooling demand needs. The controller has the main responsibility in preventing water from being wasted, improving the WUE (water usage effectiveness) of the data centre. The application of water is always a matter of balancing different aspects and constraints.  

“Even more improvements to data centre efficiency can be made through the optimisation of chilled-water systems controls. The plant manager technology can coordinate the operation of all the units and main components of the chilled-water solution. It allows an integration and coordination of the working mode between units and the main components, allowing improved efficiencies and performance at partial loads or, in the unlikely event of failure, finding the best way to react and grant cooling continuity to the system.”

A tech-powered future

Many hyperscale and colocation providers are now embracing the opportunity chilled-water systems present, not only from a cost and speed of deployment perspective, but with sustainability front and centre. Chilled-water systems present many benefits – from both a cost and speed of deployment perspective, while reducing energy consumption and emissions too. This needs to continue as we move into the next phase of the race for expanding capacity and improving the data centre carbon footprint. With such rapid expansion and increasing pressure to achieve net zero, data centre providers must rely on new technologies to meet the requirements of both today and tomorrow.  

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