Valtatie 30 produces heat for Tampere’s district heating network

The basement of an office building in Tampere houses over 12 000 servers used by various business units of Nokia. The data centre contains the servers of Nokia’s research and development centre and it serves different business units of Nokia and their tens of thousands of IT engineers all over the world in different time zones, so it must remain operational 24/7.

Building a significant data centre such as this and focusing its functions in an office building is not the most conventional or common solution. Valtatie 30 is an office property that was completed in 2000 specifically for Nokia’s use, but over the last few years it has evolved into a business park housing many diffferent companies. Typically, data centre functions are outsourced to a third party, but Nokia’s research and development unit has centralised their data center in Tampere, where the property has since developed specifically according to Nokia’s needs to support the growth of their business.

Close co-operation is at the core

Co-operation between the property owner and the customer is especially close, and together we have developed novel and responsible solutions. As the number of servers grew and the data centre required more and more space, it was time to also consider the situation in the wider context of building services. This lead to the decision to invest in district cooling in 2014.

Re-think cooling, re-use heat

“The district cooling of Valtatie 30 works by bringing cooled water via pipes, from the bottom of the nearby lake Näsijärvi to the office property. As the cooled water circulates in the piping of the property, it absorbs excess heat. The warmed up water returns to the cooling facility located in the basement where it is cooled again. Then the water is redirected to the property’s cooling network to cool the data centre and other premises,” says Property Manager Erkko Mäenpää.

Mäenpää continues: “The heat pump facility producing district heating was put into operation in 2022. A majority of the excess heat generated by the data centre is transferred to the municipal district heating network, and the process yields more cooled water to complement the district cooling. The heat stored when the water is cooled is then transferred to the district heating network of Tampere and forwarded further to heat buildings in the city.”

“Investing in district cooling was absolutely crucial so that the property could house Nokia’s growing online business operations and data centre operations in general. This cemented a close collaborative relationship with the property owner as well as their involvement in the development of the data centre also in the future,” says vLab Manager Jarkko Kytömäki from the Nokia Cloud and Network Services unit.

Kytömäki continues: ”So it is no wonder that the Valtatie 30 office building and its data centre are known within Nokia as the ‘home of the greenest and coolest data centre.’”

Power supply and security

“With Castellum, the current owner, co-operation has been more systematic and even closer than before, as Nokia can now also make decisions directly in the business unit. If an investment is seen as necessary for the growth of business operations, it can be made,” says Kytömäki. 

The power distribution of the property has also been clarified on the medium voltage level to incorporate securing the power supply of the data centre on a larger scale. To ensure the power supply, the property uses reserve power and a rotary UPS system that evens out the quality of the electricity and ensures that there is enough power for the first 25 seconds of an outage before the actual reserve power kicks in.

4 000 times a return ticket from Tampere to Tenerife

Energy efficiency and sustainability are included in the corporate strategies of both Nokia and Castellum. When aiming to achieve sustainability goals, it is crucially important that there are indicators and data that can be used to verify how well carbon neutrality is realised in practice. Both the property and Nokia use origin-certified energy. Therefore, the cooling of the property and the district heating produced by the heat pumps are both green forms of energy.

At the moment the property produces 3.6 MWs of district heating. On the annual level this means that the heat pump produces enough energy for Tampere’s district heating network equivalent to heat 2500 detached houses. As the data centre grows, the number of heat pumps grows with it, and thus the people of Tampere will have more heat energy at their disposal. 

As a result of the heat pump facility, the annual CO2 emissions of the entire city of Tampere are reduced by a total of 5 500 tons. This means savings equivalent to over 4 000 return flights for one person from Tampere to Tenerife.


“Together we have created a 10-year plan that takes into account the annual growth of the data centre. It forms the basis of all of our plans concerning infrastructure in and around the property,” Mäenpää continues.

It is the world’s only data centre located in an office building that combines district cooling using lake water and feeding district heating into the municipal district heating network. The solution in Valtatie 30 where the property owner is deeply involved in the core of their customer’s business operations is quite rare in the sector.

“We have made pioneering steps in terms of property development and energy efficiency. Of course, the collaboration centres around the fact that both parties concentrate on their own area of expertise: Nokia on growing their own business operations and Castellum on the development of the property and the maximum utilisation of the systems,” Mäenpää concludes.

”Global Real Estate Sustainability Benchmark (GRESB) has listed Castellum as a world leader in sustainable development in the Office/Industry category with a score of 92/100. These kinds of investments support our strategy of operating sustainable office properties. Co-operation between the customer’s representatives and Erkko Mäenpää, who is responsible for the property, has been effortless and professional. We hope that this close collaboration continues in the future,” concludes Castellum’s Technical Director Lauri Maila.

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