Some like it hot: how high can data centre temperatures go?


It has long been an axiom of data centre design that temperatures should be low, with all manner of dire consequences for organisations whose systems over-heat. According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the recommended temperature range for computer hardware within data centres is 18oC to 27oC.

In reality, however, most data centres are operating at the lower end of this scale, such is the fear of failure of essential systems.  “The belief is that with data centres, the colder, the better,” Nick Archer of The Uptime Institute, says “I have seen organisations operate at higher temperatures. I have even witnessed some operate in the upper 30s, but that is usually on proprietary kit where manufacturers have implemented features such as better fans to improve airflow.”

Revenue drain
This, of course, has traditionally meant that a considerable amount of capital is invested in cooling systems – approximately 25 per cent of data centre costs is spent keeping temperatures cool – and at a time when energy prices are at such a high level, this is going to be a serious drain on revenues.

Data centre operator Equinix has been looking to challenge the status quo and is looking to raise the operating temperature of its data centres.  The company is looking to implement significant improvements in efficient cooling and correspondingly lower levels of carbon emissions. It is true that many operators are already looking at reductions in energy usage, as traditionally they have been slow to adjust to demands in this area.

According to research from the 451 Group, enterprise data centres in Europe have been performing poorly with an average PUE of 2.1, a considerably high ratio that signifies poor energy efficiency.  However, companies that have opted for cloud and co-location providers, such as Equinix, are traditionally managing much better when it comes to controlling emissions. They have signed up to the Climate Neutral Data Centre Pact, aiming for a target of a PUE of under 1.4.

According to calculations from 451, if all the larger European data centres committed to this target, the energy savings could be significant, saving 11 terawatts of power every year.

Some operators are seeing opportunities for going even lower. “Pulsant is running an energy efficiency action plan forecasting out to 2025 in alignment with its PUE target of 1.3 by 2030 (also aligned with climate neutral data centre pact target),” Helen Munro, head of environment and sustainability at Pulsant, explains. “This consists of a range of elements including infrastructure such as cooling upgrades, BMS upgrades to allow optimisations in our infrastructure and airflow management.”

Greater efficiencies
Gary Aitkenhead, senior vice president, EMEA IBX operations at Equinix, acknowledges the changes that have already been made: “In the wake of increased demand, improvements in energy efficiency have helped moderate the environmental impact of data centres and data transmission networks,” he says. “Indeed, the International Energy Agency (IEA) reports that despite internet users increasing by 60 per cent from 2015 to 2021, and internet traffic growing by 440 per cent in that same time period, the energy used by data centres to power this exponential growth has limited the increase to between 10-60 per cent, thanks to efficiencies that have already been made.”

However, there is a need to push things further. There will be a growing impetus to cut costs, particularly in line with rising energy prices, and a corresponding need to reduce emissions and Equinix is one of many companies that is looking at the possibility for changes. “We recognise that meeting our target to become climate-neutral within global operations by 2030 requires a continually evolving multi-solution approach,” Aitkenhead adds. “As part of that answer, we have identified we can reduce overall power usage by increasing operating temperature ranges within our data centres to closer to 27°C.”

This is not a move that has come out of the blue: it is part of an ongoing drive to reduce energy costs, as Aitkenhead points out. “It is something we, as an industry, including technology partners and cloud service providers, have been testing at various ranges for years, to build confidence in its reliability as well as efficiency gains.”

And these gains could be considerable. “Once this initiative is rolled out across our global data centre footprint, we anticipate energy efficiency improvements of as much as ten per cent,” he adds.

Other operators are also following this path – even if they have not been so vocal about it as Equinix. “Increasing temperatures is an ongoing project for Pulsant,” Munro admits. “Running the data halls at higher temperatures presents a huge energy savings opportunity for us and by aligning limits with ASHRAE standards within the recommended operating conditions, we are still providing our clients with the right operating environment for their critical equipment. However, any such change must be well managed.

“There is a risk that warmer operating conditions will result in the client’s IT equipment consuming more power, for example if internal fans begin to switch on. So our temperature optimisation program involves incremental adjustment and monitoring of any adverse impacts, to find the true sweet spot where net power consumption is most effectively reduced.”

External environmental conditions
There are other factors at play too.  Decisions about the ambient temperature of data centres cannot be taken in isolation of external conditions.  The Uptime Institute’s Archer describes visiting one in Russia that had to cope with extremely low temperatures in winter, while sweltering in heat during the summer. “It was a data centre that had been designed so that it could operate at extremes of temperature,” he explains. “In such cases, operators have to be careful with data centre design and selection of kit. There needs to be a thorough evaluation of what changes have to be made to the way that data centres are designed and whether any equipment needed to be changed.”

Pulsant has also seen companies who have been wary of operating at the upper limits, despite the energy savings.  “Twenty seven degrees would be the maximum in accordance with the recommended range under the ASHRAE standard; whether or not we choose to go to 27 in a particular room will depend on the impacts and benefits we see during the optimisation process.  We have in a small number of cases clients who have a more restricted temperature envelope agreement, and we continue to deliver in accordance with these needs.” 

However, equipment vendors have generally welcomed the drive towards higher temperatures. “As a long-time partner, we are pleased to see that Equinix is driving efficient data centre operations through smart, sustainable operating practices,” Sue Preston, vice president and general manager, at Hewlett Packard Enterprise (HPE) says. “Optimising data centre temperatures results in more efficient operations, benefitting businesses and the planet.”

Customers will not see any immediate changes however. “Reducing overall power use by increasing operating temperature ranges within data centres will result in no immediate impact on our general customer base, as we expect this change to take place over several years,” Aitkenhead concludes.

The issue of data centre temperature is clearly going to be a battleground for the future as operators look for any chance to reduce both carbon emissions and energy costs: received wisdom could about to be turned on its head.

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