SATO makes EUR 1.5m investment in geothermal heating in Reimarla: more than 170 rental homes switch over from district heating to geothermal

20 September 2022

SATO Corporation
Press release 20 September 2022 at 11:55 am

SATO is switching over from district heating to geothermal heating in the Reimarla district of Helsinki. Unrivalled in scope across all of Finland, the geothermal heat project in Reimarla is a significant investment for SATO.

SATO has an entire block of rental homes in Reimarla in buildings completed in the 1960s and in the 1990s. In the context of modernisation, a total of nine buildings with 171 homes that used to have district heating will switch over to geothermal heating.

“Our geothermal project kicked off in 2020 and the entire area will be done by 2023. We are talking about a very large number of homes, which makes this project one of a kind in all of Finland,” says Jari Kanervo, Technical Director at SATO.

All told, the Reimarla buildings stand on around 2 hectares of land, equal to three football pitches in size. Not only is the area of land involved significant but also the size of the investment, EUR 1.5 million.

Kanervo heads the technical lifecycle team at SATO responsible for building projects in relation to energy, building services and modernisation alike. Kanervo himself has worked with geothermal heat since 2006 and been a close observer of the market for the past 15 years.

“I am very proud of our switchover in the Reimarla district. Despite being just a single site, it is an important part of our sustainability work and will help us reach our goal of carbon neutrality by 2030,” Kanervo says.

Zero-emission energy produced by 40 heat wells in Reimarla

Geothermal heating systems are an efficient way of producing absolutely zero-emission energy. One third of the heating energy used by the properties is carbon-free electricity purchased from the market while the remaining two thirds are heat energy obtained from the heat wells.

The degree of energy efficiency is illustrated by the fact that with geothermal heat, the nine buildings in Reimarla now use the same amount of energy for heating that used to be needed for just three of them.

More than 12 km of heat wells have been drilled in the area.

“Reimarla has around 40 heat wells drilled into the bedrock, each of which collects heat from a depth of around 300 metres and from an area of approximately 20 metres surrounding the well,” Kanervo describes the system.

Geothermal heat is an environmentally friendly heat source

As a responsible housing provider and developer, SATO always examines the potential for geothermal heating in the context of its new build and modernisation projects. By the end of 2022, SATO will have ground source heat pumps at some 20 properties.

“Geothermal heat is not always an option. The Helsinki region, for example, presents more of a challenge with its considerable underground network of metro tunnels, service tunnels and the like. Geothermal exploration is generally banned in groundwater areas, too,” Kanervo says.

Using heat from the ground is one of the ways in which SATO aims to move into a carbon-neutral future. With geothermal heating, energy consumption first drops to a third of what it used to be. When the remaining energy needs are met from zero-emission sources, the situation is good in terms of both the environment and energy consumption.

“We are about to reach a huge milestone any day now, when SATO’s last remaining property that still uses heating energy from fossil fuels switches over to geothermal heat, leaving SATO properties wholly free of ties to fossil fuels for heating,” Kanervo says.


  • Geothermal heating is a heating system based on ground source heat pumps that makes use of energy from the sun that is stored in the ground. Ground source heat pumps need electricity to transfer heat from the ground to the site to be heated.
  • Geothermal heating systems have the advantage over other heat pump systems in that due its high mass, the ground retains an equal temperature year round, which allows the system to work without problems even in low winter temperatures, for example.
  • The ground source heat pump works on the same principle as a fridge or freezer. The system also works both ways: when the interiors of the building need cooling rather than heating, heat may be moved into the ground and not out of it. In the summer, the heat trapped in the ground adds to the system’s wintertime capacity, meaning that when cooling needs change to heating needs, there is more heat in the ground to take from.
  • Heat wells derive their heat from the bedrock which absorbs heat from the sun. Deep down in the bedrock, the temperature stays pretty much the same year round at about 5 °C. The ground source heat pump is used to pump heat from the bedrock into the building’s heating system. When homes need cooling rather than heating, the waste heat is stored in the ground and conversely, in colder seasons the heat stored in the ground is used to heat the buildings.

For more information please contact:

SATO Corporation, Jari Kanervo, Technical Director
Phone: +358 40 513 1111,