Data centre operators are going to have to keep their cool this summer

The UK looks set for another sweltering summer – what are the implications for data centres?

One of the less talked about features of the UK in lockdown is the uncharacteristically warm weather we have “enjoyed” over the past few months. Saving a few gusts of wind here and there, London has been basking in a seemingly never ending sunny spell and the UK itself has just recorded the driest May since 1896.

It looks like we’re heading for another sweltering summer here in Britain, which let’s be honest, would be extremely well-timed as far as the nation’s citizens are concerned if stay-at-home restrictions continue to ease. 

But what of the UK’s data centre operators? We asked data centre power and cooling experts, whether given a range of Covid-19 related pressures, the prospect of summer heat-wave is leaving them unphased, or hot under the collar.

The impact of the summer season

Every Spring the Techerati inbox is flooded with content raising the alarm about the incoming Summer and whether the UK’s critical infrastructure will be resilient enough to withstand it. 

In actual fact, the danger to operational availability is pretty minimal, because operators build rising temperatures into their contingency plans. Equally, older data centres can tap temporary cooling systems to ease the burden:

“We often see requests for additional cooling, which can support during these warmer months,” explains Billy Durie, Global Sector Head, Data Centres at temporary power and cooling provider Aggreko. “However, with new data centre designs often being built with free cooling systems in place, the requirement and impact of the summer season has shifted. 

However, Durie adds that free cooling should not be considered a silver bullet: “Questions are starting to arise as to whether there is enough resilience in the systems. The concern around rising temperatures – as we have seen in the last 12 months – is whether these free cooling systems can cope with prolonged periods of elevated heat.”

As Stulz’ head of sales Scott Willock explains, higher ambient temperatures will have a significant impact, even if it isn’t catastrophic: make the cooling plant work harder, limit the amount of free cooling available and increase running costs, for instance.

In addition operators may find themselves in a situation where stand-by units are needed to meet peak cooling load. “This could result in increased maintenance costs and reduced availability / reliability.”  With Covid-19 causing spikes in data centre use and demand, these impacts will only be exacerbated this summer, Willock adds.

In simple terms, operational availability is only a risk if temperatures exceed the original design criteria for external ambient temperatures. In London, a large number of data centres employ roof chillers to handle spikes in centigrade. On top of additional cooling plants, Willock says existing plants can be reinforced with adiabatic spray systems.

Given question marks around free cooling, operators should always ensure there is a Plan B. “Can you connect a chiller, or a new cooling tower if the temperature continues to rise? If the answer is no, then the weather may impact you more than others,” Durie says. 

“Unlike power supply, which is relatively easy to scale up with additional units, mitigating the impact of overheating is complex. While designing data centres with free cooling systems in mind has its benefits, ensuring that facilities have enough connections and space for additional cooling or chillers, should it be required, can be overlooked.”

Durie recommends operators have careful contingency plans in place. For instance, facility auditing, which takes a day to organise, provides data centres with a solid plan to ensure that – should the worst happen – it can be dealt with in just 24 hours. Any new equipment should also be tested to ensure that it can cope with supply and further increases in load.

On top of that, given Covid-19 induced supply chain stresses, operators should make extra guarantees and precautions for new unit delivery, he says. “If a chiller has been ordered before the pandemic, there could be a delay in the delivery. We are already hearing of delays of up to two months.” (Aggreko itself insists it isn’t facing any supply chain squeezes).

Power pressures

What about power? One factor operators pay increasingly close attention to is grid instability as green energy production increases. Excess green energy was a contributing factor in London’s blackout last Autumn. 

Data centres deal with blackouts with backup diesel generators which typically provide 24 hours of coverage. But as Peter Walker, director, Energy Optimisation Solutions, explains, issues of grid stability and balancing are only going to increase as solar power production ramps up (which it naturally does during the summer months). 

“Grid frequency control will become more important as the proliferation of intermittent renewable generation impacts the grid and everyone connected to it,” he says. 

What of Covid-19? If the UK’s workforce continues to largely work from home over summer, there will be a significant drop in power demand. This itself causes further grid instability. 

Indeed, last month, the National Grid warned of a “significant risk of disruption to supply” unless it was granted emergency powers to disconnect excess solar and wind farms. This means data centre operators will be checking and double checking their UPSs and backup generators to keep mission-critical infrastructure protected.

“Low demand through home working and industrial processes being closed is causing havoc as the vast majority of renewable generation is distributed and is not under the control of the National Grid,” explains Walker. “This means their only option is to switch off the coal and gas plants. This increases imbalance risk due to the intermittency of wind and solar.”