Power-hungry data centres are warming homes in the Nordics

LARS PAULSSON, KARI LUNDGREN & KATI POHJANPALO Thursday, June 5th, 2025

Fortum is building heat recovery facility on the site of an under-construction Microsoft data centre in Kirkkonummi, Finland

By pairing computer processing facilities with district heating systems, Nordic countries are trying to limit their environmental downsides

WHEN Finnish engineer Ari Kurvi takes a hot shower or turns up the thermostat in his apartment, he’s tapping into waste heat generated by a 75-megawatt (MW) data centre 5km away. As its computer servers churn through terabytes of digital information to support video calls, car navigation systems and web searches, an elaborate system of pipes and pumps har vests the cast-off energy and feeds it to homes in the town of Mantsala in southern Finland.

Since it began operation about a decade ago, the data centre has provided heat for the town. Last year, it heated the equivalent of 2,500 homes, about two-thirds of Mantsala’s needs, cutting energy costs for residents and helping to blunt the environmental downsides associated with power-hungry computing infrastructure. Some of the world’s biggest tech companies are now embracing heat recovery from data centres in an effort to become more sustainable. 

Kurvi is one of the pioneers of this emerging technology: As an engineer and project manager for Hewlett Packard (HP) starting in the 1980s, he spent years working with humming stacks of hardware in hot server rooms during the freezing Finnish winters. That made him think that there must be a good way to put that wasted heat to use.

“Initially, I was focused on the health of the server,” Kurvi said. “I had this understanding that the heat inside was harmful, but when I myself went outside the building, I needed that warmth because it was cold. I came to this simple understanding: There is warmth, there is cold, and maybe we can exchange something here.”

He first applied the concept back in 2009, at a centre in Kuopio in central Finland, where the waste heat was sold back to the building’s landlord. Five years later, he scaled up and led the work at the Nebius Group NV facility, which heats his home. The project for Nebius, he said, marked a significant step up — the first time the technology was applied at such a large scale in Finland, and maybe even globally.

Inside the heat pump plant at Microsoft’s data centre site in Kirkkonummi. Waste heat recovery will account for about 1% of required emissions cuts

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