Krystal warns UK data centres face extreme weather risks

Krystal has raised concerns about whether UK data centres are built and operated to withstand periods of extreme weather. The warning comes as data centres are now part of the UK's Critical National Infrastructure.

The hosting provider is focusing on how resilient facilities are during heatwaves, flooding, water scarcity and pressure on the electricity grid. It argues that outages linked to extreme weather show climate risk is no longer a theoretical issue for the sector.

Recent incidents have brought the issue into sharper focus. The Dawn supercomputer at the University of Cambridge was reportedly knocked offline for nine days during a period of unusually high temperatures. In 2022, record 40C temperatures forced Google and Oracle to shut down parts of their London data centres after cooling systems failed to maintain safe operating temperatures.

That same summer, cooling system failures at Guy's and St Thomas' NHS Foundation Trust left staff locked out of patient records, with the disruption estimated to have cost the NHS £1.4 million. The incidents have intensified questions about infrastructure resilience as digital systems become more deeply embedded in public services, healthcare and finance.

Climate pressure

Data centres generate substantial heat because servers run continuously, making cooling systems essential to daily operations. Many facilities were designed around older assumptions about British weather, Krystal argues, leaving them under strain as higher temperatures become more common.

In hotter conditions, cooling systems spend less time in their most efficient operating modes and rely more heavily on mechanical cooling, according to the company. That can reduce operational margin during sustained heatwaves and increase the risk of outages if a cooling unit fails.

The pressure extends beyond temperature control. Extreme heat can also reduce the amount of power that overhead transmission lines can safely carry, just as electricity demand rises because of cooling needs across the economy.

If cooling systems and grid supply come under stress at the same time, a data centre can lose service quickly. Flooding presents a separate risk, especially for sites in flood-prone areas or those served by ageing drainage systems, because water penetration can affect power, cooling equipment and hardware at once.

Old and new sites

Newer facilities in the UK are more likely to be designed with higher temperature tolerances, free cooling and renewable energy in mind, Krystal said. But much of the country's existing data centre estate predates the recent run of record-breaking summers.

Retrofitting older facilities is possible, but it requires investment and a willingness by operators to identify weaknesses before they lead to disruption. That creates a divide between newer projects designed with changing climate conditions in mind and legacy sites that may need significant upgrades.

The company highlighted several measures operators are using to improve resilience. These include adding extra cooling headroom so the failure of one unit does not trigger a broader outage, using real-time environmental monitoring, securing resilient renewable-backed energy supplies, and stress-testing facilities against worst-case scenarios rather than historical averages.

Questions for customers

For businesses that rely on third-party hosting providers, climate resilience often depends almost entirely on the operator running the infrastructure, Krystal said. It suggested customers ask where their data is physically located, what flood and heat risks apply to that site, how uptime guarantees are supported, what energy sources are used and whether the provider is transparent about past incidents.

The comments also reflect a wider industry debate over whether traditional measures such as uptime percentages tell customers enough about resilience. Operators may report high availability figures, but those numbers may not show how infrastructure performs during rare but severe weather events.

The issue has become more pressing since the UK classified data centres as part of Critical National Infrastructure. The designation places them alongside sectors such as energy and water in terms of national importance, increasing scrutiny of how prepared operators are for more volatile weather conditions.

Tech industry bodies have also highlighted the risk. techUK has identified heatwaves, temperature variability, water scarcity, flooding and strain on the electricity grid as leading climate threats to UK data centres, underlining that weather resilience has become as much an operational question as an environmental one.

Dave Kimberley, Chief Executive Officer of Krystal, said the sector needs to look beyond headline uptime numbers when assessing resilience. "The majority - if not everybody - in this industry can quote you an uptime percentage to at least two decimal places. But if you ask what temperature range that number caters to, then some won't be as vocal. And that's where the real gap is - resilience is so often reported as an average, but when it comes to a drastically changing climate, averages lose their meaning.

"A data centre doesn't fail on a bad month - it fails on a single extreme day. Until 'built for extremes' is the standard data centres are actually built to, businesses are inheriting climate risk without even knowing they've taken it on."