SPECIAL FEATURE ● AIR CONDITIONING
In this month’s section on air conditioning, 8 Solutions looks at cooling in data centres, Daikin explains why clients now seek proven performance and we look at
the strict requirements for cooling and air movement in operating theatres. Plus, our CPD looks at the application of advanced variable refrigerant volume (VRV) systems
COLD LOGIC D
espite rising energy costs, data centres are spending an unnecessary amount of money on cooled air to ensure there is
no impact on data integrity or even loss of functionality. The IT equipment in a data centre should be kept at a temperature of between 18o
C and 27o C1 degrees in order
to run at optimum levels but, according to 8 Solutions, a specialist at increasing effi ciency and mitigating against the risk of down-time in critical facilities, many data centres are producing nearly four times more cooled airfl ow than is needed. The fi ndings follow a large number
of airfl ow audits that 8 Solutions has undertaken over the past six months, revealing the cooled air excesses of the majority of those audited. This trend is backed by Upsite Technologies2
done to manage airfl ow correctly. He explains: ‘As new IT equipment is added to data centres, the solution to maintain the correct temperature is usually to increase the cooling by adding further cold supply-air capacity to the environment. But, most data centres have suffi cient capacity available – it’s simply that a lot of the current cold air is being wasted and, critically, is not being directed to the IT kit.’ Main areas of wasted airfl ow include:
Unsealed fi rewalls, allowing cooled air to escape the room or data centre entirely
Unsealed cable cutouts, releasing cooled air into inappropriate areas
Poor management of hot/cold aisles, including having grilles located within the hot aisles, and IT equipment installed in reverse
, which
reported that 45 audits in the US had found data centres were producing 3.9 times the amount of air really needed. David Hogg, managing director at 8 Solutions, believes not enough is being
Poor delivery of cooled air through the subfl oor. Poor cable management causing blockages
Bypass air circulating back to the AHU without going near the IT kit
Mixing of cooled and hot air, reducing
Data centres are wasting energy by producing far more cooled air than necessary, according to David Hogg at 8 Solutions
the effectiveness of the cooled air
Incorrect airfl ow balance between supply (installed capacity) and demand (IT equipment) Hogg continues: ‘With better airfl ow management, data centres can make average energy savings of £48/m2 annum. A typical 500m2
per data centre
can save £24,000/annum and show an improvement in power usage effectiveness (PUE). This gives a return on investment of between 12-24 months.’ Recent reports by the Uptime Institute3 conclude the same, where average self- reported PUE levels have reduced from 2.5 in 2007 to 1.89 in 2011, and 1.65 in 2013, with airfl ow optimisation identifi ed as the main contributor. CJ
References 1 American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Technical Committee 9.9
2
http://blog.upsite.com/
3
http://c.ymcdn.com/sites/www.data-central.org/ resource/collection/BC649AE0-4223-4EDE-92C7- 29A659EF0900/uptime-institute-2013-data-center- survey.pdf
www.cibsejournal.com
March 2014 CIBSE Journal 57
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