Heat energy from wastewater into the district heating network to cover the annual consumption of 2,000 detached houses – Caverion implements a heat recovery system for Seinäjoen Voima in Finland
Caverion Press release 10 April 2025 at 10:00 EET
Heat energy from wastewater into the district heating network to cover the annual consumption of 2,000 detached houses – Caverion implements a heat recovery system for Seinäjoen Voima in Finland

During this year city of Seinäjoki, Finland will build a heat recovery system designed and implemented by Caverion, which utilises wastewater to provide the district heating network with heat energy equivalent to the annual consumption of about 2,000 detached houses. The system is one of Finland's first heat recovery solutions using ammonia as a refrigerant, utilising wastewater.
”One third of wastewater generated by households is domestic hot water, which means energy flowing into sewers. Therefore, we take advantage of purified wastewater, and this is a safe and environmentally friendly way to produce thermal energy for the district heating network. In Europe, very good experience has been gained with the method utilising ammonia as a refrigerant over the last ten years, and it is great that now with Caverion we get this solution in Seinäjoki,” says Pasi Salo, CEO, Seinäjoen Voima.
Best technology on the market
Caverion will implement a heat recovery system in connection with the wastewater treatment plant. A one-thousand-cubic basin will be built for the purified water. Heat pumps will utilise ammonia as a refrigerant, which is a natural, energy-efficient and environmentally friendly refrigerant. Heat pumps will produce about 4.9MW of 90-degree water for the district heating network.
”We bring the best technology on the market and Finnish industrial refrigeration expertise to this project, which strongly supports the achievement of local environmental goals. Seinäjoki is an example for other cities and regions in Finland when it comes to circular economy. We are happy partner up with Seinäjoen Voima in this project and hope to get new, energy-saving collaborations also in the future,” comments Sami Hatakka, Head of Sales, Energy solutions and Industrial Refrigeration, Caverion Finland.
Seinäjoen Voima in brief
Seinäjoen Voima is responsible for the entire production of district heat in the Seinäjoki region in Finland, with production facilities located around Seinäjoki. The combined heat and power (CHP) plant is located on the shore of Lake Kyrkösjärvi and there are other heating plants in the areas of Kapernaum, Hanneksenrinne and Puhdistamokatu.
For more information, please contact:
Sami Hatakka, Head of Sales, Energy solutions and Teollisuuskylmä, Caverion Finland, sami.hatakka@caverion.com, tel. +358 44 525 8069
About Caverion
Caverion is an expert for smart and sustainable built environments, enabling performance and people’s well-being. Customers can trust our expertise during the entire life cycle of their buildings, infrastructure or industrial sites and processes: from installation and maintenance of base and smart technologies, to managed services as well as advisory and engineering services and digital solutions.
In April 2024, Assemblin and Caverion combined to create a leading northern European technical service and installation company, Assemblin Caverion Group. Together, we are about 21,000 skilled professionals in nine countries, sharing the passion for smart and sustainable solutions. Our combined revenue amounts to SEK 42 billion (EUR 3.7 billion).
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