Innovation

OnZero, a Viennese Company, Will Heat 70,000 Helsinki Homes With AI Waste Heat

Jakob Steinschaden02. September 2026, 08:50

A company with Viennese roots will soon feed waste heat from AI computing into the district heating network of the Finnish capital. OnZero Finland Oy, a subsidiary of Vienna-based OnZero Alpha Holdings GmbH, recently signed an agreement with the energy utility Helen Ltd, which is owned by the City of Helsinki and ranks among Finland’s largest energy companies.

The facility, which OnZero calls an AI Heat Factory, is expected to supply up to 525,000 MWh of heat per year. According to both partners, that covers the heating needs of roughly 70,000 apartments in Helsinki and works out to a continuous thermal output of about 60 MW. Commissioning is currently scheduled for next year.

Liquid Cooling Instead of Evaporation

OnZero relies on a liquid-cooled architecture that was designed around heat recovery from the start. Conventional data centres release most of the heat their servers produce into the environment. The company’s liquid-cooled systems are instead built to recover up to 99 percent of the heat generated by AI computing and to deliver it at temperatures suitable for district heating networks. Because that heat goes into the network rather than through evaporative cooling, the operators put on-site water consumption at zero. Where recovered heat replaces natural gas, OnZero puts the saving at roughly 1,500 tonnes of CO2 per MW of installed heat recovery capacity per year.

For Helen, the model is familiar territory. The utility has been using data centre waste heat since 2010 and has signed agreements with operators including Equinix, as Data Center Dynamics reports. “Helen can utilise waste heat recovered from OnZero’s data centre in Helsinki’s district heating system,” says Tuukka Toivonen, COO for Strategy and M&A at Helen. He calls it a cost-effective way to reduce combustion-based heat production. By 2040, the company wants to phase out combustion-based energy production altogether.

“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,” OnZero CEO Ali Siddiqui says in the announcement.

Who Is Behind OnZero

The operating company, OnZero Global Solutions GmbH, is registered in the Quartier Belvedere district of Vienna, with Vlado Stanic and Alexander Dietrich listed as managing directors. Both come from crypto infrastructure: they previously ran Blockbase Mining, a mining-as-a-service provider whose first installations sat in shipping containers next to small Austrian hydropower plants. That experience with power-hungry computing at cheap energy sites is the foundation of today’s business model.

The management team is led by Ali J. Siddiqui, a financier with an international track record. According to the company’s own account, he co-founded the zero-carbon steel venture AGSI, founded JS Private Equity and served as Pakistan’s ambassador to the United States. CFO Christoph Cerar was previously group CFO at Steyr Motors and headed financial planning at cooling equipment maker AHT, part of the Daikin group. COO Stephen Smith co-founded JS Private Equity and was CFO of Techpacific Capital in Hong Kong. Heat technology is run by Antti Porkka, who built waste heat recovery systems at Calefa.

By its own description, OnZero earns money in three places at once: computing power for AI and blockchain workloads, heat sold to district heating utilities, and grid stabilisation services, since computing loads can be shifted flexibly.

Two Sites Are Already Running

Helsinki would be by far the company’s largest site to date. According to its website, two facilities in Finland are currently in operation: Kemijärvi in Lapland went online in the middle of last year, followed by Kerava near Helsinki in the autumn. Together they have delivered around 30,700 MWh of heat so far, which the company says corresponds to roughly 3,800 households. OnZero reports a PUE of 1.02 for both sites, a very low figure. A further site is in development in Fagersta, Sweden.

The project is also intended to serve as a reference for the company’s planned expansion into further European countries. OnZero is targeting regions where growing demand for AI computing meets existing district heating networks or other heat users such as industry.

The approach lands on a live nerve. The AI boom is driving up electricity demand from data centres, while the EU Energy Efficiency Directive requires waste heat to be used wherever it is technically and economically feasible. In Austria, the same idea hung for a long time on the planned AI Gigafactory in Vienna, whose waste heat was meant to help supply hundreds of thousands of households through the district heating network. That link to a specific site became impossible to maintain once the EU rules shifted towards procuring computing power rather than a classic partnership: Vienna eventually dropped its bid.