Air Tightness in Data centre

Air Tightness in Data centre

Calum Maclean, senior research engineer atBSRIA, discusses data centre airtightness and energy efficiency.

Airtightnessis sometimes a forgotten hero of energy efficiency and because of the highenergy demands in data centres, any savings will be magnified significantly.The airtightness of many components and the ensemble is important in datacentres or stand-alone racks.

The demands

Firstly, the reliability of the equipmentand power supplies is paramount in the uptime of a system. Any risk ofoverheating or contamination in the system can affect equipment lifetime andconsequently the uptime of the data centre.

Improving and controlling the airdistribution and movement in any data centre type will help achieve energyefficiency, and, therefore, cost effectiveness. Any air movement outside of thedesigned air paths (leakage) will affect the distribution of the cooled air andmay also introduce contaminated air into the data centre.

The air paths are different for thedifferent applications, from CRAC-cooled, raised-floor data centres toindividual water-cooled racks with internal fans passing air through awater/glycol cooled coil. Airtightness is vital in maintaining the energy efficiencyof any building. Any cost savings can accumulate into a significant saving inall of the examples above, however, in the case of a search operator thesavings are magnified by the number of data centres utilised.

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Applying airtightness

Airtightness can be applied in a wide rangeof situations in data centres and data centre equipment, including wholebuilding, floor voids, contained aisles, container, standalone racks and evensome individual components (CRAC units etc).

Whole building airtightness is important sothat refrigerated or conditioned air inside cannot escape but also so thatuntreated outside air cannot get in. The effect of wind on buildings can bedramatic in a building with poor airtightness and lead to significant airflowpath changes internally and possible cooling inconsistencies.

Floor void leakage can have a significantimpact on the distribution of cold air. Floor tiles should be sealed prior toand during installation and the air paths identified during design andminimised during construction. Cold air from the void can leak into the coldaisles, or other chilled areas prior to the servers, which may be useful interms of cooling, but cooling will be inefficiently distributed. On the otherhand, if the cold air leaks into the hot aisles or return air paths, this willlead to cooling losses and inefficiency.

When contained aisle construction isutilised, the airtightness of the containing structure is paramount indelivering the chilled air onto the racks removing the hot air in cold/hotcontainment, respectively. Any loss in the pressure differences due to leakagecan affect the overall air distribution in the racks, putting equipment at riskof overheating or causing rack temperature to be non-uniform and/or outside therecommended limits.

The systems utilising container style andstand-alone racks should incorporate airtightness criteria in their design inorder to minimise the ingress and egress of air into and out of the systems.The container systems are at particular risk as they are able to be placedoutside and, therefore, the wind effects can be significant as with the wholebuilding setup.

Ideal opportunity

The design and build phases of any new datacentre, or even the upgrade of an existing one presents the ideal opportunityfor investigating and minimising the air leakage paths from any data centretype.

Low air leakage levels in different datacentre applications can minimise the amount of active cooling being lost to thesurrounding spaces or into a hot aisle, reducing the amount of cooling requiredand associated costs.

Improving airtightness will also reduce theingress of untreated, potentially contaminated air (e.g. dust particles) whichcould cause system failures.

Lower air leakage levels will furtherimprove the air distribution in the data centre, providing the righttemperature and relative humidity conditions, therefore, reducing the risk ofdegradation of the equipment. Reducing the risk of equipment degradation andmaximising the cooling capacity by good air distribution will ultimatelyimprove both uptime and cost efficiency.

Airtightness should be thought about forany project and any piece of equipment throughout the design and build phases,to plan for success.

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