# A Finnish district-heating network has used data-center heat since 2015.

Mäntsälä’s utility has circulated recovered server heat into the town-centre district-heating network since 2015. Nivos said in 2025 that it supplied about one-third of the network’s heat.

Canonical: https://brightaifuture.com/discoveries/mantsala-data-center-heat
Format: discovery
Source publication: 2025-08-27
Bright publication: 2026-09-19
Substantive update: None recorded
Evidence and review: Deployed; confidence: medium; approved; ai-assisted. AI-assisted editorial comparison with the cited original and supporting public sources, bounded claims and explicit status labels. Bright did not independently audit the underlying records.

## The human problem

Servers release low-temperature heat, but that heat is only useful when a nearby customer, pipes, temperature lift and commercial agreement line up.

## The prior constraint

Without a district-heating network and heat pumps, waste heat is usually rejected to the environment.

## AI’s actual role

Computing creates the heat stream; the useful public outcome depends on conventional heat-network engineering and utility operation.

## The documented result

Nivos reports that heat recovery from the Mäntsälä facility has fed the town-centre district-heating network since 2015. Heat exchangers capture server-room exhaust heat and electric heat pumps raise its temperature before Nivos distributes it. The utility said in August 2025 that recovered heat supplied about one-third of town-centre district heat.

## Why it may matter

It is an operating case that makes the enabling conditions for heat reuse visible: proximity, pipes, temperature lift and a buyer for the heat.

## Limitations

Published annual figures describe different periods and measures: 30, 25, and about 20 gigawatt-hours should not be collapsed into one current total.

Bright did not find a current independent meter series or heat-pump electricity total.

The result depends on nearby demand, heat pumps, a district network, commercial terms, and backup heat sources.

## Unresolved questions

What is the current annual metered delivery after ownership and facility changes?

How much electricity do the heat pumps consume?

How do heat price and carbon intensity compare with the displaced supply each year?

## Provenance and history

{
  "dates": {
    "eventDate": "2015",
    "publicationDate": "2025-08-27",
    "captureDate": "2026-09-19",
    "lastReviewedDate": "2026-09-19"
  },
  "provenance": {
    "origin": "editorial",
    "externalId": "https://nivos.fi/ajankohtaista/nivos-sopi-sahkoliittyman-suurentamisesta-mantsalan-laajenevalle-datakeskukselle-suunnitteilla-myos-hukkalammon-lisahyodyntaminen/"
  },
  "revisions": [
    {
      "id": "revision:data-centers-mantsala-data-center-heat-01",
      "recordedAt": "2026-09-19",
      "summary": "Added direct historical Nivos, Calefa and Nebius citations; separated their dated 20, 25 and 30 gigawatt-hour claims; retained Nivos’s 2025 one-third network share as the clearest recent denominator.",
      "sourceIds": [
        "source-nivos-2024",
        "source-nivos-heat",
        "source-nivos-heat-2019",
        "source-calefa-mantsala",
        "source-nebius-mantsala-2024"
      ]
    }
  ],
  "corrections": []
}

## Original sources

- [Nivos update on the Mäntsälä data center and heat recovery](https://nivos.fi/ajankohtaista/nivos-sopi-sahkoliittyman-suurentamisesta-mantsalan-laajenevalle-datakeskukselle-suunnitteilla-myos-hukkalammon-lisahyodyntaminen/)
- [Nivos operational update on data-center heat](https://nivos.fi/ajankohtaista/uusista-konesaleista-lisaa-puhdasta-lampoa-mantsalaan/)
- [Nivos historical reference on the Mäntsälä heat-recovery plant](https://nivos.fi/ajankohtaista/paikallisen-datakeskuksen-kanssa-yhteistyossa-luotu-ekosysteemi-lammittaa-mantsalassa/)
- [Calefa supplier reference for the Mäntsälä heat-pump plant](https://calefa.fi/en/references/heat-pump-plant-for-producing-district-heating/)
- [Nebius October 2024 Mäntsälä expansion and heat-recovery release](https://assets.nebius.com/assets/281aef5c-ec3c-4be7-81a4-559cd1fbe992/Nebius%20to%20triple%20capacity%20at%20DC%20in%20Finland.pdf?cache-buster=2025-06-13T16%3A06%3A05.488Z)

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