Stoltinmaja | Turku

As Oy Stoltinmaja, located in Runosmäki, Turku, decided to get its energy affairs in order all at once. The biggest expenditure item, district heating, was replaced by geothermal heat, which cut the amount of energy purchased by around 71%. The investment decision was facilitated by an ARA energy grant of around EUR 400 000.

For geothermal energy, 15 energy wells were drilled on the site, with a total depth of 5 000 metres. In addition to geothermal heating, an exhaust air heat recovery system was installed and the building automation system was upgraded. In addition, an exceptionally large solar power plant of 115 kilowatts was installed on the roofs of the houses. The roofs of six apartment buildings were almost completely covered with solar panels.

“It supplies electricity for the building’s saunas, cold rooms, stairwell lights and yard lights. Solar power can also be fed into the apartments and sold to the national grid,” says Kari Hirvonen.

Another special feature is that temperature and humidity sensors were installed in each apartment. In general, there are only a few dwellings with condition sensors. Comprehensive metering reduces unnecessary maintenance visits and helps improve energy efficiency by allowing precise control of heating water flows to the apartments.

In addition to cost savings, the board is motivated by responsibility and green values. The project reduced the carbon footprint of the housing company by around 70%.

“We will become fossil-free and green. So let’s be fashionable.”

As part of the cooperation, LeaseGreen guaranteed that the SCOP of geothermal energy will remain at least at 3.4. The benefit guarantee is part of the LG Meta service contract, which is initially signed for five years. The contract includes remote monitoring to proactively optimise energy consumption and conditions according to weather conditions. For this purpose, digital twins of geothermal and LTO systems and condition measurements will be modelled. Monitoring improves energy efficiency and reveals faults quickly.

Contents of an energy renovation

• Geothermal heat
• Exhaust air heat recovery
• Solar photovoltaic
• Automation
• Antooring in every dwelling
• Intelligent steering
• Remote monitoring