In western Finland, energy company Vatajankoski and local firm E-Heat have just launched a very practical experiment (and becoming less and less “experimental”): a 1 MW modular data center, directly connected to the urban heating network. Instead of “throwing away” the heat generated by the servers, they convert it into part of the thermal supply for the town of Honkajoki, located in the Satakunta region, within the eco-industrial area of Kirkkokallio.
The idea, explained straightforwardly: computing heats, and that heat—well-captured—can replace part of the energy previously produced by boilers or combustion systems. Here, the residual heat from the data center is used to heat water up to nearly 80°C, which is then injected into Vatajankoski’s district heating network.
Exactly what they deployed (and why it matters)
The project is based on an increasingly common approach in infrastructure: containerized data centers. Essentially, it means packed IT capacity in modules (containers) that can be quickly deployed, expanded in blocks, and operated with a very “industrial” logic: standardization, shorter installation times, and controlled footprint.
The Honkajoki data center is 1 MW, and its heat will help meet the thermal demand of the urban area. The change is so significant for the local grid that the previous installation—Puistotie grate boiler—was shut down last month and will serve as backup plant. According to Ari Niemi, Vatajankoski’s urban heating manager, the goal is that “most” of the heat is produced without combustion, using “data heat.”
The “sysadmin” perspective: when your cooling becomes an energy product
For system administrators and operators, this kind of integration shifts the mindset: cooling stops being just a cost and becomes part of an external value chain (a heat network) with expectations of continuity.
In such a scheme, thermal design and operation become more important:
- Thermal stability and control: if the data center supplies a heat network, predictability is key (steady loads, controlled ramps, well-calibrated alarms).
- Heat exchangers and circuit separation: the usual practice is to isolate the data center circuit from the district heating circuit to protect both worlds (water chemistry, pressures, maintenance).
- Redundancy and safe degradation: when heat is useful, but service availability remains pivotal, operating modes may include degraded operation (e.g., diverting heat to conventional dissipation if the thermal network isn’t absorbing).
- Plant telemetrics: beyond typical IT monitoring (temperatures, flow, pressure, consumption), there’s an increasing focus on OT/energy KPIs: thermal stability, supply/return consistency, heat exchanger efficiency.
This doesn’t require “magic”—it demands operational discipline. The interesting part is that the economic/municipal incentives drive correct execution.
Not an isolated case: Vatajankoski has been scaling this approach
This deployment has a history. Vatajankoski already installed a 2 MW data center at its Kankaanpää plant back in 2024: a 12 rack project that, according to reports, supplies around 20% of the local district heating. Additionally, last year Vatajankoski and E-Heat deployed a 1.5 MW module in Merikarvia, also aimed at feeding a heat network.
The roadmap continues: E-Heat has announced plans for a 1.8 MW module in Ivalo, in Finnish Lapland, in partnership with local provider Inergia Lämpö Oy. The 80 m² module is expected to be operational in spring and will cover “about half” of the heating network’s needs.
The financial aspect: moves around E-Heat
The model is also attracting corporate interest. Finnish real estate firm Toivo invested €2,000,000 in E-Heat last year and had been in the process of acquiring the company, but ultimately sold its stake in November to its current owner for approximately €1,971,280 (around 1.9 million euros).
Moreover, Toivo reported ongoing negotiations for a potential deal with E-Heat and committed to a guarantee of ~€675,000 as part of a €6,000,000 investment program planned for 2025. They also mentioned that a possible reclassification of Finland’s electricity tax could influence the final decision.
In parallel, a Toivo report on E-Heat indicated that the company has eight ongoing projects totaling 20 MW, in addition to completed projects and those under construction.
Why this approach might set trends in Europe
The message is simple: reusing heat turns data centers into urban infrastructure. This approach particularly suits countries with mature district heating networks, where replacing combustion with recovered heat has immediate benefits in cost and emissions (without waiting for the “next big battery” or “revolution”).
For the data center sector, it also offers a compelling narrative: social and political license to expand (especially where new expansion faces energy limits or permitting challenges). And for operators, it adds an interesting layer of complexity: your data center no longer just meets digital SLAs; it can literally support a city’s thermal comfort.
via: DataCenterDynamics