What factors determine the energy efficiency of a data centre? Where is the energy used? Local Climate Data Hall Temperatures Chiller / DX Energy Condenser / Dry Cooler / Cooling Tower Energy Pump Energy Fan Energy UPS Losses Transformer Losses Switchroom / UPS cooling Ancillary Losses
What Factors Determine the Energy Efficiency of a Data Centre? REDUCING ENERGY CONSUMPTION Eliminate / minimise the use of mechanical refrigeration Operate data halls at higher temperatures (consider on board IT equipment fan energy can run at higher speed with higher inlet temperatures and consume more energy) minimum 24 C supply in summer Separation of hot and cold air streams Match cooling air flow rate to IT equipment air flow rate Operate data halls at lower relative humidity in winter to reduce humidification load No air conditioning to UPS switchrooms ventilation only Operate UPS in ECO mode Further Energy Optimisation Heat recovery
Data Centre Energy Efficiency Measurements The most commonly used data centre efficiency metric is Power Usage Effectiveness (PUE) PUE = Total Facility Energy Usage IT Equipment Energy Usage The ideal PUE is 1.0 although this is not practically possible Typical Data Centre PUE s o Legacy Data Centre: 2.0 3.0 o Chilled Water with Free Cooling: 1.3 1.6 o Indirect Mass Air Cooling: 1.15 1.25 o Direct Mass Air Cooling: 1.10 1.20 PUE CANNOT ACCOUNT FOR ENERGY GENERATED FROM SUSTAINABLE SOURCES OR RECOVERY OF HEAT ENERGY FOR EXPORT
Data Centre Energy Efficiency Measurements To take into account the true energy efficiency and sustainability of a data centre a different metric should be used. The Green Grid have proposed Carbon Usage Effectiveness (CUE) CUE = Total CO2 emissions caused by the Total Data Centre Energy Energy IT Equipment Energy CUE takes into account sustainable energy generated on site but does not take into account Green Energy supplied to the site by the Utility Company. This can be taken into consideration by the Green Energy Coefficient (GEC). GEC = Green Energy Used by the Data Centre Total Data Centre Source Energy Whilst CUE and GEC have some improvements over PUE it still does not take into account the export of recovered heat from the data centre. To take into account energy which is recovered from the data centre and exported for use in other facilities the Energy Reused Factor (ERF) has been devised. ERF = Reused Energy Outside of Data Centre Total Data Centre source Energy
Should Data Centres have a Special Responsibility To Contribute to a Sustainable Future? It is estimated Data Centres consume up to 3% of the world's electricity generation, and Data Centres energy demand is growing and will continue to grow in the next years Data Centre are becoming the new polluters Today the focus is on reducing energy use and carbon emission of the Data Centre facility In temperate and cold climates the subject of heat recovery needs to be given a higher priority Source: Data Centre Knowledge In the future more and more projects will integrate Data Centres in district heating systems increasing energy efficiency of both Data Centres and District areas Data Centres and District Heating Heating produced as waste of the Data Centre processes can be collected and redistributed to residential and commercial final users, considerably reducing the amount of fossil fuel utilized Several projects in the recent years showed the potential of this scheme However this is still new in the Data Centre Industry and there is large room for improvement Source: IBM Zurich Research Laboratory
NICK VANEY RED ENGINEERING DESIGN Email: nvaney@red-eng.com Tel: +44 (0)7770 944 087