• • • DATA CENTRE MANAGEMENT • • •


Why accurate energy management calculations are more critical than ever for data centre cooling


With energy prices increasing globally and an ever-greater focus on the need to reduce emissions from carbon-intensive industries, the need to manage energy use accurately and effectively at data centres is becoming increasingly important. Neville Child, global product line specialist, recording and control at ABB, explains how this can be achieved using the latest generation of data recorders


S


o much of the world today is driven by data. From smart meters, smart cities, and smart factories to maps that update journey time,


algorithms that suggest your next meal, t-shirt, or pet choice, all of this data needs to be stored. It is little wonder that statistics from the International Energy Agency (IEA) suggested that data centres accounted for around 1% of global total electricity consumption in 2018, with projections pointing to an increase of up to 13 percent by 20301 as the world becomes more digital. A data centre is simply storage for data, a space


used by businesses to house their computer systems and associated components. They can vary in size from a dedicated room in an office building to entire warehouses with racks of server space rented to various organisations. With the increase in data traffic that resulted from the pandemic, where both people and businesses turned to remote communications as a solution, there has been a worldwide boom in the construction of data canters, with new facilities being built in increasing numbers. With data centre equipment in constant use, it


is vital to be able to manage ambient conditions to prevent overheating. Large server racks produce a lot of heat while in operation and if the racks are allowed to overheat the entire system fails. This is clearly unacceptable, so climate control systems are installed to prevent overheating.


Managing energy use Minimising energy use by data centres will be instrumental to their owners meeting ever narrower emissions targets and minimising their environmental impact. To achieve this, it is vital that energy use is calculated accurately to deliver optimum energy efficiency. Energy calculations are used in a variety of


applications to calculate the amount of energy used to heat a system or process, with the resulting information then being used to derive a total value that is used for billing purposes. However, in climate control applications, these same energy calculations can also be used to assess the amount of energy that is required to cool a process.


16 ELECTRICAL ENGINEERING • APRIL 2022 electricalengineeringmagazine.co.uk


How are data centres cooled? A continuous flow of cold water in pipes around hot server racks removes heat from the server racks with the flow rate being determined by how hot the servers become. Water is used because of its incredibly high specific heat capacity. The specific heat capacity of a substance is the amount of energy that must be added, in the form of heat, to one unit of mass of the substance to cause an increase of 1 unit in its temperature. Specific heat capacity varies by substance, such


that temperature will be different for each state of matter but is particularly high for water. As water needs to absorb a large amount of heat energy to raise its temperature by a degree, it is therefore an ideal substance for cooling purposes.


Chiller capacity A chiller provides chilled water to air conditioning units within a building or series of buildings. It is important to know how much cooling a chiller can produce to calculate the energy that is needed to maintain conditions at a specific temperature. To be able to calculate this, some values must


be known, specifically the volume of water flowing into the evaporator and the temperature of the supply and return water to the chiller. The below diagram shows the system variables that must be measured:


Photo supplied by Jessica Child


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