Helsinki Enters Its Second Winter Without Coal – Reliable Heat Supply Even During Severe Cold Spells
Helsinki is entering its second heating season without coal. The reliability of district heating supply now rests on a more diversified production portfolio and new investments that strengthen the flexibility of the energy system and ensure sufficient heat availability even during prolonged periods of severe cold. During the 2026–2027 heating season, Helen will increase its district heating production capacity by more than 400 megawatts through newly commissioned investments. This is equivalent to the district heating demand of a city the size of Jyväskylä during periods of extreme cold.
Demand for district heating rises sharply, particularly during extended cold spells. In Helsinki, heat production is based on a range of complementary technologies, including heat pumps, electric boilers, bioenergy and recovered waste heat. Additional production capacity will also come from the new heat pumps and electric boiler at Eiranranta.
“Helsinki’s heat production is built on a diverse mix of technologies that complement each other. The role of any single plant or fuel has become less significant than before, strengthening the security of supply across the entire system,” says Timo Aaltonen, Senior Vice President, Heating and Cooling at Helen.
Preparing for Extended Cold Spells
The most challenging situations for heat production are prolonged cold periods when the weather is both extremely cold and calm. In such conditions, heat demand rises rapidly while wind power generation may remain low.
To prepare for these situations, Helen maintains peak-load and reserve heat plants, whose role is to safeguard heat supply even on the coldest winter days.
In 2025, the reliability of Helen’s district heating supply exceeded 99.9 per cent, meaning that heat was delivered to customers with virtually no interruptions.
“We have phased out coal, and our next objective is to move away from combustion-based energy production altogether. At the same time, we remain firmly committed to maintaining security of supply, even during the coldest winter days. Our system includes sufficient capacity to manage exceptional circumstances, such as extremely cold and windless periods. This ensures that Helsinki residents continue to have access to reliable heating when they need it most,” Aaltonen continues.
New Investments Increase Flexibility Across the Energy System
During the 2026–2027 heating season, Helen will commission new electric boilers, heat pumps and thermal energy storage facilities at Patola and Hanasaari. Together, these investments will increase district heating production capacity by more than 400 megawatts.
In addition, the new thermal energy storage facility at Hanasaari will be capable of storing approximately 1,000 megawatt-hours of thermal energy. This corresponds to the annual heating energy demand of around 200 apartment blocks. The key benefit of thermal energy storage is that heat can be stored when energy is abundantly available and then utilised later when demand increases.
In addition to strengthening security of supply, these new investments improve the flexibility of the energy system and help balance fluctuations in heat demand under varying weather conditions. At the same time, they support Helen’s goal of transitioning away from combustion-based heat production.