The AmbiHeat heat pump plant, built to Savon Voima’s Joensuu power plant, is the first of its kind in Europe in terms of its overall solution. It innovatively utilizes both waste heat from flue gas scrubber and river water as heat sources.
Joensuu Heat Pump Plant Named Best in Europe
Together with Savon Voima Oyj, Calefa has brought international recognition to Finland.
The AmbiHeat heat pump solution, completed in summer 2025 at the Joensuu power plant, has just won the Heat Pump City of the Year Award in Brussels.
The award is granted to a significant, innovative, and sustainable heat pump project on a European scale.
“This is a major recognition of our long-term work in developing new types of solutions for district heating production,” commented Kari Anttonen, Business Director at Savon Voima Oyj.
Innovative Use of Flue Gas Scrubber’s Condenser Heat and River Water
Calefa’s AmbiHeat heat pump plant supplies heat to the Joensuu district heating network from two sources. The primary source is the power plant’s flue gas scrubber, whose condensation heat is directly upgraded by the heat pump plant for district heating.
This world-class heat pump technology not only significantly enhances the efficiency of the flue gas scrubber but also provides approximately 7 MW of additional heating power to the Joensuu district heating network during winter.
“Multiple heat sources improve the efficiency of the heat pump’s operation and enable year-round development of district heating production efficiency,” Anttonen explains.
Adding a unique twist to the Joensuu implementation is the second heat source: river water.
By utilizing two heat sources, the heat pump plant remains a profitable investment even during summer, when the power plant’s boiler is not producing heat. In this case, the heat pump switches to using river water as its heat source, allowing it to meet the lower summer heat demand.
“In summer river water mode, the AmbiHeat heat pump plant delivers about 4–5 MW of power,” describes Calefa’s Antti Porkka.
Unique Heat Pump Technology on a European Scale
The award granted by the European Heat Pump Association (EHPA) highlights the significance of the plant, which includes four heat pumps. No similar implementation of this scale exists elsewhere in Europe.
“The award is a great testament to the work we’ve done for years together with our customers—developing ever-larger heat pump plants while innovatively responding to their needs,” says Calefa CEO Petri Vuori.
Savon Voima’s heat pump project has also received EU NextGeneration funding. This has enabled the integration of waste heat solutions into the Joensuu power plant’s energy production. Even in summer river water mode alone, the AmbiHeat plant covers a significant portion of the summer heat load.
“Our goal is carbon-neutral district heating by 2030, and this heat pump project is a major step toward that goal. It also helps ensure competitive and environmentally friendly district heating for our customers in the future,” says Anttonen from Savon Voima.
The award ceremony organized the 23rd of September by Euroepan Heat Pump Association in Brussels, recognizing pioneering heat pump implementations from across Europe. This marks the third time a Calefa project has been honored at the annual awards gala. In 2021 an AmbiHeat Heat Pump plant for Orion Oyj’s Turku medical plant won the DecarbIndustry Award, and in 2015 a solution recycling datacenter waste heat to district heat in Mäntsälä won the Heat Pump City of the Year Award.
For more information, please contact
Petri Vuori
CEO of Calefa Oy
+358 40 553 4427
petri.vuori@calefa.fi
