Do Urban Data Centres Hubs Like Slough Exacerbate Heatwaves?
For years, Slough has had a reputation among Britons as an unremarkable place, thanks in no small part to the fact it was the setting for smash-hit sitcom The Office, which depicted it as a provincial, parochial backwater.
More recently, however, Slough has become truly noteworthy in its own right. The satellite town is now the world's second largest data centre hub, home to some 40 large-scale facilities.
Many of these data centres sit on a single campus close to the high street, making it very different to the isolated campuses that are often found in China or the US.
The operators of the sites include industry heavyweights Equinix and Digital Realty, while the list of tenants reads like a roll call of Big Tech, with Amazon, Google, Oracle and Microsoft all relying on Slough.
According to some industry estimates, Slough's total data centre load is around 1GW which, for context, is enough electricity to power hundreds of thousands of homes.
But the plans for Slough have not stopped. In fact, they are only just beginning, with more capacity already planned on the edge of the existing campus.
However, the UK's recent heatwave has exposed a worrying effect of Slough's data centre boom which has residents panicked.
The science of a hotter neighbourhood
Data centres run thousands of servers and switches that generate constant heat, with their cooling systems work non-stop to protect the ultra-sensitive electronics inside. That cooling process, however, expels warm air into the surrounding area.
Researchers have started measuring what this does to the immediate environment.
A preprint study led by academics at the University of Cambridge looked at decades of satellite data from data centre sites worldwide.
Andrea Marinoni, an Associate Professor at Cambridge and one of the paper's authors, says that the research controlled for factors such as urbanisation and the broader climate crisis.
Even after that adjustment, the team found a robust average temperature increase of 2°C near data centre clusters.
In some cases the rise reached as high as 9°C, though it is important to note that these examples came from data centre complexes in Brazil and Spain, not the UK.
A new generation of scale
Andrea cautions that this research focused on facilities built over roughly the past two decades, which generally draw no more than 100MW of power.
At 1GW, Slough's cluster sits in a different category altogether.
"Slough is almost like an experiment by itself in the sense that the new investments in data centres are bringing to life a new generation of data centres," he tells The Guardian.
"What we measured were what we can call the first generation of data centres that were the ones that were implemented in the last 20 years. Slough is a different context for the scaling up of data centres, and is something that is quite unprecedented."
Local readings appear to back up the wider pattern. A weather station near the data centre campus recorded a high of 36.7°C on Wednesday and 36.5°C the day before.
A second station further into town, away from the cluster, measured 36.2°C and 34.7°C on the same two days.
Naveed Hussein, who has lived in Slough all his life, told The Guardian that the change in climate has been noticeable.
"People are questioning, why is it so hot? It's getting hotter," he said.
An opportunity in the waste heat
The same heat that troubles residents could, however, be a potential resource going forward.
The UK Government has proposed capturing waste heat from data centres to warm homes through district heating networks, the likes of which are commonplace in Scandinavia.
The upsides are obvious, however substantial the outlay – this kind of initiative could save energy, reduce heating bills and slash emissions from boilers.
Whether or not Slough's operators adopt that kind of approach is uncertain.
But, for now at least, the cluster's growth shows no sign of slowing, even as the mercury keeps climbing.
