OnZero Finland is taking a different approach to the growing energy burden of AI infrastructure by connecting a planned Helsinki data center directly to the city’s district heating system. The Austrian AI data center developer signed an agreement with Finnish energy company Helen to recover heat from high-performance computing and feed that energy into Helsinki’s existing heat network. The project could deliver as much as 525,000MWh of heat annually, a volume the companies say could meet the heating needs of approximately 70,000 apartments in Helsinki. Operations could begin sometime next year, giving OnZero an early commercial test for treating compute heat as an infrastructure resource rather than a waste stream.

AI Heat Factory moves from concept to deployment

The agreement anchors OnZero’s AI Heat Factory commercial deployment strategy, which combines high-density AI computing with heat recovery at the infrastructure level. Rather than separating cooling from heat rejection, the design connects both functions through a liquid-cooled architecture that captures thermal output from AI workloads. OnZero claims the system can recover up to 99 percent of the heat generated by the data center and deliver that heat at temperatures suitable for district heating networks. That distinction matters as AI facilities push rack densities higher and operators face growing pressure to improve energy and cooling efficiency without simply expanding resource consumption.

“We founded OnZero with a clear objective: to lower the cost of AI by combining high-performance AI infrastructure with the efficient recovery and productive use of compute heat. Our agreement with Helen demonstrates how this approach can work in practice – turning heat generated by AI computing into a valuable resource for Helsinki’s district heating network,” said Ali Siddiqui, CEO of OnZero.

Water efficiency becomes part of the proposition

OnZero also positions water efficiency as a core part of its infrastructure approach, an increasingly important consideration for data center developers operating in regions where cooling resources face competing demands. The company says its facilities use zero on-site water, while the system sends recovered heat into district heating networks instead of relying on evaporative cooling to reject thermal energy. The internal coolant runs through a closed loop, allowing the system to remove heat without ongoing water loss during the cooling process. However, the zero-water claim remains a company-stated design characteristic rather than an independently verified performance result in the announcement.

The Helsinki project gives OnZero a market where it can integrate heat reuse with an established urban energy system instead of treating sustainability as a standalone feature. District heating can provide a direct outlet for recovered thermal energy, creating a commercial pathway for data center operators to extract additional value from infrastructure that traditionally serves only a cooling function. OnZero expects the project to become a reference deployment as it expands into other European markets, where district heating availability could influence how developers assess potential AI infrastructure locations. Meanwhile, heat recovery economics will depend increasingly on the relationship between compute density, cooling efficiency, network temperature requirements and the value of displaced heating demand.

OnZero expands across the Nordic region

The Helsinki development also builds on OnZero’s existing footprint in Finland, where the company currently operates facilities in Kemijärvi and Kerava. Beyond those locations, the developer continues to develop additional sites across the Nordic region and wider European market as demand for AI computing infrastructure grows. OnZero operates from its Vienna, Austria headquarters while developing its broader Nordic strategy. The expansion signals that OnZero views heat recovery not simply as a feature for one Helsinki facility, but as a core component of its intended infrastructure model.