With sustainability now a major differentiator in the data centre market, organisations must find ways to ensure their facility’s carbon footprint is kept to a minimum. With cooling the second largest consumer of power within a data centre, Marc Garner, VP, secure power division, Schneider Electric UK&I, explores the crucial role of cooling in achieving data centre sustainability and why a more holistic approach could be the way forward.

Data centres are the foundational building blocks of today’s digital and electric world. In 2020, their importance was well and truly amplified, with demands for mission-critical applications and connectivity surging, and the growth of data that ensued.

According to IDC’s Global DataSphere, more than 59 zettabytes (ZB) of data would be created, captured, copied, and consumed across the world in 2020.

This has been driven by an increase in the number of employees working from home, greater use of video communication and a surge in the consumption of downloaded and streamed video.

IDC also states that the creation of new unique data, and the increased consumption of replicated data has fuelled the growth of the DataSphere, which is forecast to continue at a five-year compound annual growth rate (CAGR) of 26% through 2024.

Today, data centres, and the professionals that work within the digital infrastructure sector, continue to play a crucial role in meeting connectivity and application demands.

So significant has the data centre industry become, that during the course of the Coronavirus pandemic, many engineers and service providers were named key workers, helping to ensure operational continuity for the many businesses transitioning their organisations to remote working.

The sector itself is built upon a reputation for reliability and there’s no doubt that key requirements of any data centre include performance, resiliency, security and efficiency. Yet looming large in the conscience of operators and customers is a factor that’s become more pivotal than any single facet of the technology realm. Now, with greater awareness of the impacts of data centre carbon emissions on the environment, sustainability has become a key focus for the industry.

Data centre sustainability

Climate change and in many respects, sustainability, is now driving government and corporate agendas. Concern for the health of the planet is a matter of global importance, and has become the responsibility of both businesses and consumers alike. The Paris Climate Change Agreement calls for < 2°C warming by 2030, while the current projection is at + 3° C.

In January 2020 The Guardian reported that the climate crisis fills the top five places of the World Economic Forum’s risks report. By 2035 is is anticipated that IT will consume 8.5% of global electricity up from 5% in 2018, and with data centres responsible for a large share, the industry will play a key role in driving more sustainable operations.

Looking inwardly, a recent survey of more than 800 global data centre providers by Schneider Electric and 451 Research found that nearly all (97%) of respondents had customers who demanded contractual commitments to sustainable practices; the majority (57%) believed that efficiency and sustainability will be important competitive differentiators within three years – a large increase on the 26% who believed that such was the case at the time of asking; and nearly half of respondents (43%) had already put in place strategic sustainability initiatives and efficiency improvements for their data centre infrastructure.

Clearly, market forces as well as regulatory pressures, are encouraging 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 redution 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, their 2020 annual survey found that around 95%c of respondents said that 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 program 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 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 (PPA’s) 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 vendor-agnostic 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 and 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.