The same kilowatt doing two jobs.
The best thing a modern compute hall can do for the place it sits in is to stop treating its own heat as waste. In the Nordics, the numbers line up almost perfectly: a datacenter runs year-round, a district heating network needs year-round thermal energy, and the temperatures a modern cooling loop can deliver are the temperatures a well-designed low-temperature network can absorb. The kilowatt that powered a training run inside the hall leaves the site a second time as winter heat for a school, a factory hall or a municipal building next door.
That is a better outcome for the town, a better outcome for the customer's sustainability profile, and — when the offtake is there — a better effective-PUE than any chiller optimisation can deliver on its own.
Designed in from the first line drawing.
The reason waste-heat recovery works at a GreenGridLabs site is that the offtake path is one of the first design decisions, not the last. Before a site goes into engineering, the local team has already asked the local heat-network operator a handful of specific questions: what temperature do you need on the supply side, how much thermal power can you take on the hottest and coldest days, and how does that change over the next ten years as you upgrade the network. Those answers then flow back into the compute-hall thermal envelope, the cooling loop temperatures and the piping layout.
That is why the offtake actually works when it is commissioned. It is not bolted on — it is one of the constraints the site was built around.
Dalsbruk is the first full example.
Dalsbruk on Kimitoön sits on the edge of the Ovako steel-wire plant at Brukviken, with the municipal district heating network of Kimitoön a short pipe run away. That proximity is the reason we chose the location in the first place: the thermal profile of the compute load lines up with what the industrial neighbour and the local heat network can actually absorb. The heat path is simple — a plate heat exchanger transfers energy into a low-temperature loop, and from there into whichever offtaker is calling for heat. Nothing exotic, nothing that has to be invented for this site.
Commissioning the offtake arrangement is happening in parallel with the rest of the Dalsbruk build-out. When it is complete, the same site will be delivering three things from one 10 kV connection: green compute, grid-balancing services, and winter heat for its own town. That is a more interesting footprint than any of the three on its own.
How we report it.
Every site we operate reports two PUE numbers: the design PUE of the hall in isolation, and the effective PUE once the waste-heat offtake is counted as useful thermal output. We publish both separately so customers, regulators and municipalities can see the delta for themselves. Where an offtake is not yet energised, the effective number is not claimed — it simply is not reported for that period.
The underlying principle is simple. The clean-power and circular-heat story is the reason these sites exist in the Nordics at all. It has to survive contact with an engineer, a utility contract and a published number. When it does, the result is a datacenter that makes its town warmer — not just greener on paper.