Ilmalanrinne will soon use renewable geoenergy

30th January 2024
News Large properties

A parking garage that has been in continuous use, drilling geowells to a depth of up to 600 meters, building an energy center in a former storage space – these are just a few of the phases that describe the geoenergy project that began last summer in Ilmala, Helsinki, Finland. What is up with the project now?

In Ilmala, Helsinki, along the Hakamäki fairway, there is a building complex consisting of five office buildings. The first three office buildings, A-C, of Kiinteistö Oy Ilmalanrinne 1 were completed in 2015. Sweco Oy maintains its premises there.

Next to these buildings, on top of the old parking garage, an extension of the building complex was completed in spring 2023. Two new office buildings, D-E, or Ilmalanlinna, continue the elevated view along the route. The property is managed by CBRE, and in addition to Sweco, there are tenants such as Uponor, Netox and DNA.

When driving to the parking garage from the foot of building A, you understand the name “Ilmalanrinne”, which in Finnish means slope of Ilmala. The office buildings are built on a slope, which is reflected in the continuous gentle uphill slope in the parking garage.

Since July 2023, the parking garage has been the stage for a geoenergy project.

Geoenergy transition in office buildings almost complete

Adven’s Project Manager Ilkka Tahvola stands in the parking garage in worksite clothing. There is a sigh of relief on his face. Now the worst of the rush is over, as the first phase of the geoenergy project, which covers the A-C buildings of the site, is soon finished.

“The drilling of geowells began in July 2023 in the parking garage, which has been in operation throughout the project. Drilling was completed at the end of the same year. In the parking garage the drilling proceeded one area at a time, and that area was closed to traffic. Elsewhere in the parking garage, the parking spaces were in use normally,” Ilkka Tahvola explains. He continues:

“A tight schedule, dealing with several subcontractors and coordinating tasks, as well as partly taking care of the implementation of the construction at the site , have employed more than the average project. Drilling was the busiest phase, and small delays also changed the starting times of other work. During the drilling, the geoenergy center and the geoenergy field pipeline were also built in stages. However, everything was successfully completed.”

The first buildings in Ilmalanrinne will switch from the current district heating and cooling system to geoenergy-produced heating on 1.2.2024. Geocooling will be introduced during spring 2024.

The following two buildings are in the second phase of the project, and their geoenergy center is currently under construction. They will be transferred to Adven’s energy production in summer 2024.

Black pipes, geowells and project management

A total of 41 geowells, approximately 300 meters deep, have been drilled into the soil of the parking garage, and are connected to stainless steel insulated main lines running through the ceiling of the garage.

Inside the main lines passes heat recovery fluid. It most often consists of a mixture of water and ethanol. In the collection pipes, the liquid heats up from the heat of the soil and thus geothermal heat is obtained from geowells, which is transferred to the property’s heating system through the ground source heat pump.

The roof of the parking garage has main lines with heat recovery fluid circulating inside.

The pumps run on electricity but produce more heat than the electrical energy they consume.

Adven uses certified wind power in its ground source heat pumps and electric boiler, which enables completely carbon-neutral heating and cooling.

One of six manifolds in the parking garage to which 41 geowells are connected. In manifolds, each well can be closed, if necessary, for example for maintenance. Each manifold has 6–9 wells connected. There are a total of 6 manifolds throughout the property and 2 collector wells for deeper wells drilled outdoors. In total, 54 geoenergy wells have been drilled throughout the property.

Because the plot of the property is very cramped and in order to obtain enough energy from the soil, deeper than normal wells have also been built at the site. Outside the parking garage, a total of 13 geoenergy wells have been drilled at the entrance to a depth of up to 600 meters. At Adven’s geoenergy implementations, wells are usually about 400 meters deep.

“The implementation of the project has been very exceptional, as most of the 54 geowells were drilled under the property’s parking garage. Space was scarce from this point of view, especially since the parking garage was in use all the time. Another exception to a normal geoproject was the drilling of 600-meter geowells. It has been very interesting to lead this project, as we have never done similar “basement floor projects” in such a scale and under these conditions ,” Ilkka Tahvola says.

From storage space to geoenergy plant

In the future, Ilmalanrinne’s five office buildings are supplied with heating, hot water, and cooling from two Adven geoenergy plants. The centers are also located under the office buildings in the parking garage.

Geoenergy centers produce about 3 GWh of energy annually. In the future, geoenergy itself will cover approximately 98 per cent of the heating energy needs of the entire property. In case of exceptionally cold weather, there is an electric boiler as back-up. The entire cooling energy requirement of the property is produced with geothermal energy.

The geoenergy center for the A-C buildings has been built in a former storage space of the parking garage, which was partially expanded to the parking garage side. The plant is a compact space of about 60 square meters, which can accommodate all the equipment needed for energy production.

The energy solution of A-C houses includes, for example, 9 ground source heat pumps, buffer tanks for hot water and the heating network, expansion tanks, a heat exchanger for condensate removal, electrical center, and a 500 kW electric boiler.

“We wanted to invest in security of supply, which is why several small ground source heat pumps were chosen instead of one large one. They are easier to maintain, as heat production does not depend on just one pump,” says Ilkka Tahvola.

The ground source heat pumps have been installed in Adven’s energy center and are ready for use after some finishing touches. The pumps are highly automated.

In the future, during the summer, when the property is cooled, condensate energy will be stored by means of a heat exchanger in a geoenergy field that acts as an energy storage like a battery. So nothing goes to waste!

Geoenergy as a service

The project has been implemented using Adven’s Energy as a Service® (EaaS) service model, which means implementing the entire energy solution on a turnkey basis, from design to finished implementation, its financing and, once completed, energy production and continuous maintenance.

For example, the energy service includes simulations when designing a geoenergy solution. In order for the heat wells to be dimensioned correctly in relation to the heat demand, the temperature of the well field is simulated for 50 years to come.

“When a real estate energy solution is implemented using Adven’s EaaS service model, the property can only enjoy the end result, i.e. reduced energy costs and CO2 cuts. All other activities related to energy production are then on our shoulders,” Adven’s Sales Director for Real Estate Energy Jarmo Maunu sums up.

To ensure service and maintenance, the energy plant in building A-C has already been connected to Adven’s remote control, even though the project has not yet been handed over from the project phase to the maintenance phase. The plant is monitored around the clock from the operational center located in Vantaa, Finland. The energy plant of the D-E buildings will also be connected to remote control once completed.

“Ilmalanrinne as a whole is a great example of how excellent planning and implementation can implement a carbon-neutral energy solution also for an existing property located on a cramped and challenging plot. A responsible energy solution cuts out CO2 emissions as a whole and also lowers annual energy costs,” Jarmo Maunu says.

Project in numbers:

  • 54 geowells, of which 41 are approx. 300 m deep and 13 approx. 400-600 m deep
  • A-C building’s energy center has 9 ground source heat pumps
  • D-C building’s energy center has 6 ground source heat pumps
  • Total energy production approximately 3 GWh
  • 500 kW electric boiler for backup and peak consumption
  • Geoenergy reduces carbon dioxide emissions by 460 tonnes per year
  • Implementation with Adven’s Energy as a Service® service model
  • 24/7 monitored geoenergy installations
  • The first phase will be completed on 1.2.2024, the second phase in summer 2024

For more information:

Adven, Sales Director Jarmo Maunu, tel. +358 50 320 2622,


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