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Energy efficiency
Improving data centre efficiency
Anu Kätkä, global product manager for Vaisala’s Industrial Measurements, explains why accurate monitoring is key to energy efficiency in data centres
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ata centres and server rooms perform critical roles; enabling organisations to function normally. They employ information technology (IT) devices which are powered by electricity, and the electricity used by these devices is ultimately converted into heat, which must be removed by cooling equipment that also runs on electricity, unless cooling can be achieved by outdoor air (economisation, for example).
Data centres need to be monitored continuously, accurately and reliably for a number of reasons: 1. Data centre failure can be disastrous 2. Data centres are often un-staffed 3. Data centres are often located remotely 4. Computers and servers generate localised heat, which can result in hot-spots
5. The performance of IT equipment is affected by temperature and humidity
6. Data centres consume high levels of energy Despite the fact that data centres are often unmanned and located in remote areas, they are expected to run for 24 hours, every day of the year. The risks associated with data centre failure are therefore so great that mitigation measures, such as redundancy, are common. However, monitoring enables energy efficiency as well as lowering risks to IT infrastructure.
What are the risk factors? The performance and longevity of processors, fans, hard drives and memory components can be significantly affected by humidity and temperature. It is also important to avoid chassis and circuit trace corrosion, as well as circuit board delamination. The latest IT equipment is able to operate in a wider range of environmental conditions than was previously possible, but concern exists with older hardware that may be beyond its warranty period. What are the objectives? The operators of data centres continuously seek to lower risks, reduce operational costs and protect the performance of IT equipment. The American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) has established standards for data centres to protect consumers and enterprises, as well as minimising operational costs by establishing temperature and
humidity specifications that do not over-cool or over- process the data centre environment. Energy consumption: It has been estimated that data centres are responsible for 1-2% of global electricity consumption. Data centres have grown in size and number as the demand for internet services has grown. Between 2010 and 2018, the amount of data travelling on the internet increased more than ten-fold, while global data centre storage capacity increased by a factor of 25 (Masanet et al. 2020). The demand for internet services and computer intensive applications is projected to continue to grow. While IT systems are becoming more efficient, this increased demand for electricity is a concern because it represents both a financial cost as well as a significant contribution to greenhouse gas emissions, which cause climate change – unless the electricity can be obtained from renewable sources. Improving efficiency with accurate measurements: Economisation represents a low-cost option for cooling, and further efficiency can be achieved with evaporative or adiabatic cooling. Monitoring is undertaken to enable these measures and to ensure that IT equipment is maintained within acceptable limits. It also ensures that humidity is not too high; causing condensation risk, or too low; causing static electricity risk. It is also necessary to minimise temperature fluctuations which may affect IT infrastructure.
Control systems can only be as precise as the measurements, so accurate and stable instrumentation enable the cooling system to be efficiently controlled while maintaining the correct levels of temperature and humidity. Obviously, there
should be a sufficient number of sensors in the spaces, rooms, ducts, pipes and outdoors to ensure that the system is able to implement effective control. Temperature is a key measurement, but humidity parameters are also important. Dew Point is useful where temperature and humidity control of spaces is necessary; wet bulb temperature is used for cooling tower control; enthalpy is used to determine whether to use fresh or reconditioned return air, and relative humidity is useful for human comfort. Factors affecting the choice of sensor: To minimise requirements for operational staffing, it is important that sensors and transmitters should be reliable, accurate and stable. In addition, they should be simple to calibrate on-site, without disturbing measurements, and ideally allow interchangeable plug-and-play sensors.
Instruments should offer a long (proven) lifetime, which is a major advantage for Vaisala customers. For example, Vaisala’s humidity and pressure sensors have been measuring on Mars in the ‘Curiosity’ rover since August 2012 and in the ‘Perseverance’ rover since February 2021. The core technologies employed by these sensors are the same as those deployed in applications here on Earth. Energy is a major component of data centre efficiency, so reliable, accurate monitoring is necessary in order to enable the optimisation of energy consumption including cost and energy saving measures such as economisation. In addition, sensors and transmitters with long-term stability and a long lifetime help to further reduce operational costs and maintenance requirements.
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September 2021 21
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