Extensive geothermal heat survey steers Helsinki towards its carbon neutrality goals

Helsinki is preparing a new underground master plan to steer the planning of large rock spaces and tunnels. The plan will also contribute to planning a denser urban structure, as underground and rock spaces can be utilised in a versatile manner and functions can be transferred underground.

When it was time to update the underground master plan, Sweco’s experts carried out a geothermal heat survey to support the process. “The plan proposal is expected to be completed at the turn of the year,” says Eija Kivilaakso from the City of Helsinki’s City Planning Department, who is responsible for the plan.

Geothermal heat is expected to be the solution to both the increasing population numbers and the City’s climate goals. The City of Helsinki aims to achieve carbon neutrality by 2035. One solution worth considering is geothermal heat. “Carrying out a survey on the potential of geothermal heat became necessary while we were preparing the planning principles of the new underground master plan,” says Project Manager Pekka Leivo from the City of Helsinki’s Technical and Economic Planning Unit.

Sweco’s experts surveyed whether the underground resources are sufficient for building both geothermal wells and new underground spaces, as well as facilities such as traffic tunnels and water management plants, in different areas. “We also assessed how much of the city’s total heating needs could be covered with geothermal heat,” states land use specialist, Architect Maritta Heinilä from Sweco.

Dense urban construction poses a challenge to geothermal heat

Helsinki’s underground master plan in 2011 was the first of its kind. The geothermal heat survey by Sweco was also the most extensive one ever carried out in Finland. One part of the survey focused on land use planning, involving environmental impact assessments and geographic information surveys.

“We also sought solutions to legal questions, as equal treatment of landowners is highly important in the planning process and thus in the planning of geothermal heating,” Heinilä emphasises.

Another area was the planning of geothermal heat and energy systems. “We assessed the City’s total heating needs and simulated geothermal heat fields exceptionally one area at a time. The conventional way is to carry out the simulations building by building,” says geothermal heating system specialist Mika Penttinen.

It was important to the City of Helsinki that matters were examined from several different perspectives. “Sweco has very broad subject matter expertise in regard to land use and technical planning,” Leivo says.

Combining building services data with geographic information revealed where there was space for geothermal heat. “Densely placed and tall buildings are often at odds with the spatial requirements of geothermal heat systems. The greatest potential lies in single-family house areas,” says Sweco’s Lifecycle Design Project Manager Niina Laasonen.

The survey provided the City with information for further planning. “We now know the potential of geothermal heat and that geothermal heat does not work as a property-specific system in efficiently built areas,” Leivo says. “With that in mind, we should turn our attention to regional geothermal heat systems. That will enable us to utilise the potential of geothermal heat in the best possible way.”

Construction of geothermal wells must begin this year

The survey indicates that geothermal heat can be used to ensure the achievement of Helsinki’s carbon neutrality goal and produce, according to a theoretical calculation, 14–18% of the City’s total heating need in 2035.

The geothermal heat capacity will only be sufficient if the City’s heating needs remain at their current level. “Harnessing the potential of geothermal heat requires immediate action, such as energy renovations by housing companies and space reservations for regional energy solutions,” Laaksonen says.

The City is ready for the next steps. “If we adopt geothermal heat as part of normal land use and public utility planning, it will facilitate the implementation of regional geothermal heat systems outside block areas as well,” Leivo concludes.

“Sweco has very broad subject matter expertise in regard to land use and technical planning.”
– Pekka Leivo, the City of Helsinki

“Regionally, we will be able to utilise the potential of geothermal heat in the best possible way.”
– Pekka Leivo, the City of Helsinki

“If we adopt geothermal heat as part of normal land use and public utility planning, it will facilitate the implementation of regional geothermal heat systems outside block areas as well.”
– Pekka Leivo, the City of Helsinki