FEATURE
data centre operators to take a strategic approach to being more efficient , but how in practice does the industry become more sustainable ?
PUE and sustainability
A key mechanism for driving data centre efficiency is in the type and management of the cooling architecture deployed . Typically , the cooling system is the second largest consumer of power after the IT equipment itself , meaning that any change here , positive or negative , can have major implications for the carbon footprint of a facility .
PUE ( Power Usage Effectiveness ) has encouraged the adoption of strategies to improve the efficiency as well as the effectiveness of cooling , and today the reduction of metric is one of the key ways that many organisations gauge their success .
According to the Uptime Institute , ‘ PUEs have fallen from an average of 2.5 in 2007 to around 1.6 today ’, and furthermore , its 2020 annual survey found that around 95 % of respondents said it is important that colocation companies have a low PUE . However , when this is compared with 451 Research ’ s survey , stating only 43 % of operators had a strategic sustainability programme to comprehensively improve the way they design , build and operate their infrastructure , it identifies a major gap in the sector – one that must be addressed quickly .
PUE and sustainability are clearly intertwined , but it ’ s becoming inherently
Marc Garner , VP , Secure Power Division , Schneider Electric UK & I
obvious that a more holistic approach to sustainable data centre deployment strategies is required . Today , operators must also consider other factors to drive sustainability including power purchase agreements ( PPAs ) with stringent site
selection and planning processes , where access to renewables is a deciding factor in location . Use of resource efficient data centre designs will also be crucial , combining them with AI and vendoragnostic management software as a mechanism to support lower PUE ratings .
However , as facility designs continue to evolve and demands for more power and processing continue to drive rack densities , cooling loads will inevitably become greater , thereby meaning an increase in potential emissions . How then , can operators continue to feed the burgeoning appetite for digital services while maximising efficiency and minimising environmental impact ?
The role of cooling in data centre energy efficiency
Traditional cooling strategies have used chillers to cool the ambient air within a data centre , while fans or InRow air cooling can provide additional cooling to the racks . For more efficient operation , variable-speed fans can run at reduced speeds to match a lower cooling load with strategic use of containment to create ‘ hot ’ and ‘ cold ’ aisles that streamline the thermal profile and ensure efficient cooling .
For years , ‘ air ’ has been the go-to , but facility location has also become a deciding factor in cooling strategies . Based on the natural climate , further efficiencies can also be achieved by using free cooling , in which cold air coming from outside the data centre can be used to cool the interior so that chillers can be temporarily switched off or run down .
Modern operating conditions are also causing data centre operators to consider new variants of liquid cooling . Now with increasing power densities and concerns for the environment , the operating cost savings of liquid cooling can offset the capital costs that are required to prepare a data centre for its deployment .
Today , for example , between 40 – 60 % of the heat generated by a server can be absorbed by using a Direct Liquid Cooling ( DLC ) approach , reducing the burden on air chiller systems and the accompanying costs . Research detailed in Schneider Electric White Paper # 282 , Capital Cost Analysis of Immersive Liquid-Cooled vs . Air-Cooled Large Data Centres , found that liquid cooling can offer many tangible benefits including higher energy efficiency , smaller footprint , lower noise pollution and up to 14 % CapEx savings .
With the demand for digital services showing no signs of slowing , the need to drive sustainability while balancing greater requirements for resiliency is becoming paramount . Addressing one part of the data centre alone is not the answer , but any improvement in PUE or efficiency via cooling will amount to enormous savings – both in terms of energy usage , cost and carbon emissions . ◊
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