cooling

Steve Davis of Next Generation Data gives some guidance on how to get more efficiency out of your cooling system .

( PUE ). With cooling typically accounting for 40 per cent or more of a data centre ’ s total energy bill , the more that can be done to optimise and reduce cooling the better from cost , environmental and legislative perspectives .

There are various options and alternatives available – some only within the grasp of new build rather than legacy facilities – including the harnessing of climatically cooler locations that favour direct air and evaporative techniques ; installing intelligent predictive cooling systems ; using water , liquid or nano-cooling technologies ; along with prerequisite aisle containment techniques – hot or cold .

A fundamental step towards improving cooling efficiency is to move away from perimeter cooling whereby CRACS circulate cold air via raised floor plenum . Instead , adopt a hot aisle / cold aisle configuration with racks aligned in rows and server exhausts facing one another to create the hot aisle . Combined with the separation of hot and cold air streams through either hot ( HACS ) or cold ( CACS ) aisle containment , this approach will enable cooling systems to be set to higher temperatures , saving more energy while still providing safe operating temperatures for IT equipment .

Often used in combination with traditional perimeter cooling , the CACS approach encloses the cold aisle to separate the hot and cold air streams allowing the rest of the data hall to become one single hot air plenum . The addition of cold aisle end curtains or doors and ceilings will further reduce the mixing of air streams .

Inherent inefficiencies While CACS is certainly a big improvement on cooling efficiency compared to the sole reliance on a perimeter only approach , there are inherent inefficiencies . This is due to the distance and pressures and therefore energy required for distributing sufficiently chilled air from the perimeter CRACS to the servers .

There are also limitations with CACS on rack cooling densities ( over 6kW ) due to the limitations of distributing sufficiently cold air through raised floors . Higher densities require higher airflow and producing and driving larger volumes of cold air

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