How chilled water cooling can play a part in unlocking sustainable data centre growth  

With society’s appetite and reliance on digital services growing and the prospect of a future virtual world, digital technologies are a fundamental part of our everyday existence.

According to Fortune Business Insights, the digital transformation market size is projected to reach USD 3,546.80 billion by 2028 exhibiting a CAGR of 22.1 per cent during the forecast period. 

At the same time, data centre providers are embracing strict policies to drastically reduce their carbon emissions in order to help achieve sustainability targets.  So, like many businesses, data centres are looking for new solutions that can meet their ambitious energy efficiency and carbon neutrality targets. 

With this in mind, chilled-water systems, critical to allowing data centres to operate effectively, are a viable way for providers to not only support increasing demand cost-effectively and with minimal disruption, but also reduce their carbon footprint and help meet sustainability objectives. The reduction of emissions goes through two fundamental aspects: the reduction of direct emissions and the reduction of indirect emissions. 

Direct emissions 

When it comes to reducing global warming potential (GWP) of data centre operations, traditional refrigerants are already being replaced by HFO (hydrofluoro-olefin) refrigerants. However, most of these new 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.   

A viable solution to this issue is chilled-water systems. The refrigerant is contained within chiller units and, in most applications, these are installed outside of the data centre, which simplifies the use of flammable fluids. They are also one of the first cooling technologies to apply low GWP refrigerants in data centre applications and are a valid alternative for reducing direct environmental impacts. 

Indirect emissions  

Reducing carbon footprint also means cutting the electricity consumed by a data centre during its operation. This is where chilled-water systems can play a big role. For example, in a chilled water system, the chiller compressor is the greatest consumer of electricity, and the warmer the external climate, the greater the electricity demand of the compressor. In recent years, there have been a range of cooling system efficiency improvements that allow a reduction of indirect emissions and therefore electricity usage. 

Inverter-driven compressors are becoming more widely used, helping to achieve higher efficiency levels -, especially at partial loads. Chillers equipped with inverter driven screw compressors, or oil-free centrifugal compressors, are now available to drastically cut down electricity consumption. 

ASHRAE has helped by increasing the recommended operating temperature of data centres equipment up to 27OC. This has allowed subsequent increases to the water temperatures within chilled-water systems which has extended use of freecooling chillers – even in countries or climates where freecooling wasn’t previously viable.  Freecooling technology has an important advantage as it allows for cooling without activation of the compressor.  

The adiabatic technology can improve the efficiency of a chilled-water system even more. As the water in the pads evaporates, the air is chilled then delivered at a lower temperature, achieving a higher freecooling capacity of the chiller and a more efficient operation of the compressor. The unit control enables the use of water when strictly needed, according to redundancy, efficiency or cooling needs. This prevents 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. 

Further improvements to data centre efficiency can be achieved through the optimisation of chilled-water systems controls. Chilled plant manager technology can coordinate the operation of all the units and main components of the chilled-water systems. It allows an integration and coordination of the working mode between units and the main components, enabling 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. 

By combining all the technology optimisations, chilled water systems can significantly reduce the direct and indirect emissions.  

About the Author

Andrea Moscheni is Thermal Management Product Application Manager at Vertiv, Andrea began his career in 2012, joining the heating and cooling international industry as application engineer. In 2015 he joined Vertiv as product application manager for the EMEA region, specializing in CRAC and CRAH cooling products for data centres. He has been actively involved in the pre-sales phase in some of the largest EMEA data centres, collaborating with the main customers.

From 2018 he has been focusing on product management activities on CRAH and other chilled water applications for Thermal Management solutions. Andrea attended Padua’s University where he received a master’s degree in Energetic Engineering.