LUMI Supercomputer (CSC Kajaani)

The story

Housed in a decommissioned UPM paper mill in Kajaani, Finland, LUMI (Large Unified Modern Infrastructure) is a 380-petaflop HPE Cray EX supercomputer owned by a 10-nation European consortium. Built with AMD EPYC CPUs and MI250X GPUs, LUMI is universally regarded as a world benchmark for green computing. Powered entirely by local hydro and wind energy, the machine utilizes warm-water cooling with zero compression chillers, keeping PUE at an extraordinary 1.05. Even better, its cooling system exports hot water to Kajaani's municipal grid, covering one-fifth of the town's annual heating needs.

Notable

• Reaches 380 petaflops sustained Linpack performance as Europe's most powerful pre-exascale supercomputer.
• Installed inside an abandoned paper mill in Kajaani, central Finland, drawing 100% local hydro and wind electricity.
• Operates 100% warm-water cooling with no chillers, producing a world-leading PUE below 1.05.
• Exports all server waste heat to Kajaani's municipal district heating network, heating 20% of the entire city.

Expansions

• 2020: Kajaani former paper mill selected by 10-country European consortium for LUMI
• 2022: full 380 petaflop system formally inaugurated
• 2024: integrated into Nordic AI and quantum computing testbeds