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Heat Storage Tank Vattenfall – Berlin

Power generation

Germany's largest heat storage tank, with maximum energy-efficiency

Berlin is taking a significant step towards achieving its clean energy goals with the inauguration of Germany’s largest heat storage facility this year. With this groundbreaking project, owner Vattenfall aims to improve the way surplus heat is stored and used: with a storage capacity equivalent to around 350,000 bathtubs, this colossal heat accumulator promises to play a pivotal role in Berlin’s energy security and transition towards a greener, carbon-neutral society. Combined with Europe's largest power-to-heat conversion plant located nearby, the heat storage will help increase the use of excess renewable energy from the grid. 

With a height of 45 meters, a diameter of 43 meters and a capacity of 56 million liters, Germany's largest heat storage tank will store district heating water at a temperature of 98 degrees Celsius.

"Heat storage is an important component regarding flexibility in the grid, which is needed to feed in more and more renewable energies. With smart storage solutions, the heat supply of the future will not only be more climate-friendly, but also more secure.”

Christian Feuerherd - CEO of Vattenfall Wärme Berlin AG

Delivering competitive and reliable insulation solutions

At ISOVER, we are committed to providing insulation solutions that are both competitive and reliable. Our approach is rooted in building strong relationships with installers, partnering with distributors, and backed by valuable reference projects. Through our comprehensive support and high-quality products, we aim to meet the unique needs of our customers and contribute to sustainable construction practices.

Key facts & figures

  • Largest heat storage tank in Germany
  • Inauguration in 2023
  • 56 million liters (equals approximately 350,000 bathtubs)
  • 12.000 m² tank wall insulation
  • 5.000 m² tank roof insulation
  • 400 mm insulation thickness


Our milestones for success

In this specific project, several elements were key in winning the contract and making the installation a success:

Effective thermal calculations

At the beginning of the project, only two parameters were explicitly specified regarding insulation. One was the mineral wool density of 22 kg/m³, to ensure sufficient mechanical strength. The second was the maximum heat loss of <12  W/m².

Our colleagues at ISOVER Germany were able to perform the right calculations according to the AGFW FW 313 standard, to precisely optimize the insulation thickness required for this specific project. As a result, 400 mm of our Glass Wool felt FE (AS) SI were installed around the tank, in two layers of 200 mm each. From a technical point of view, this perfectly optimized solution set us apart from our competitors.
Beyond the required heat loss reduction, the challenge was also to reduce installation costs, given the gigantic dimensions of the project, and all the more so as construction deadlines were tight.
In total, 12,000 m² of tank wall insulation and an additional 5,000 m² of roof insulation were used for this project! 

Building strong relationships

We should also mention the close relationship we had with the installer on this project. Indeed, their previous experience with our glass wool felt reassured them and favored our collaboration on this project. Throughout the project, our colleagues from ISOVER Germany accompanied the various stakeholders, providing technical support whenever needed.

After all, our offer was not only technically convincing, but also commercially attractive. Indeed, thanks to our complete package including the insulation of the tank walls and roof, we were able to remain competitive. Finally, Vattenfall attaching the utmost importance to the safety of people on its sites, we had to put in place specific measures, particularly in terms of packaging and logistics. Our aim was to give priority to transparent supply chain management, which enabled us to meet project deadlines without compromising quality and safety.

Vattenfall: A trusted reference from a leading energy supplier

This collaboration for Vattenfall demonstrates the quality and reliability of our insulation solutions. We are honored to have been chosen as a supplier, which encourages us to continue to offer excellence, and opens the doors to future projects.

Vattenfall: goal to be climate neutral by 2040

Finally, we should mention the ecological ambition of this project led by Vattenfall, which meets the challenges of tomorrow and contributes to the objectives set by the company and the German government. At Saint-Gobain, we are proud to participate in the development of large-scale decarbonization projects. This way, we work together, with our customers, to making the world a better home. 

Learn more about sustainable insulation in industry

Insulating Germany's largest heat storage tank