How the National Football Stadium sets a new environmental standard

Our energy optimization solutions can be found at the National Football Stadium. After the installation of our flexibility brAIn software system for heat pump regulation, the stadium’s energy manager and electricity supplier, Slovenské elektrárne - energetické služby, also decided to implement a smart battery storage brAIn by FUERGY, taking the “greenest stadium in Europe” to the next level. Read more about this unique project.

  • Published: 18. 03. 2024
  • Written by: Fuergy

The stadium, also known as "Tehelné pole", is not only a base for the Slovak national football team, it is a place where fans gather to support their heroes on the pitch, a place for culture that is a symbol of belonging.


The stadium was built in 1940 in the capital of Slovakia, Bratislava. It was closed in 2009 and demolished four years later. In its place grew the most modern and technologically advanced stadium in Central Europe, with a UEFA category 4 certification. It has a capacity of 22,000 seats and also includes a shopping center, a twenty-storey office building and residential apartments.

The facility’s energy supplier, Slovenské elektrárne - energetické služby s.r.o. (SEES), managed the design and implementation of the entire energy infrastructure, and continues to maintain and operate it to this day. The goal was, and always will be, to provide the stadium with the most sustainable solution at the lowest possible cost.

According to the SEES proposal, low electricity usage is ensured by water to water heat pumps with a total output of 3150 kilowatts, which continue to be the primary energy saving technology. In 2023, they were responsible for up to 80% of the cooling and heat in the entire stadium complex through renewable energy sources. In addition, rainwater is also collected and used throughout the stadium, in restrooms or irrigation for example.

At FUERGY, however, we push the boundaries of energy efficiency, especially on the cost side. In order for Slovenské elektrárne to be able to make the most of the existing energy infrastructure, both economically and ecologically, we designed tailor-made solutions, which were deployed in two stages.

Stage one – deployment of the flexibility brAIn solution for heat pumps

Heat pumps installed in the stadium are not only used to heat and cool the entire complex, but also to produce non-potable water and maintain indoor temperatures, even in the summer months.

Heat pumps are also a prime example of technology that offers a huge regulation potential. Thanks to the flexibility brAIn, we can turn the devices from ordinary appliances into a technology that helps stabilize the entire electrical network and saves CO2e emissions. This is done by fully automating the power output of the heat pumps according to the needs of the stadium and the entire power grid, providing so-called non-certified ancillary services.

Regulation takes place in cooperation with a superior system for measurement and regulation, so-called regulation or MaR, implemented for heat pumps. The MaR system has preset upper and lower output limits which do not allow the FUERGY system to exceed the permissible power and in no way limit the supply of heat or cooling to the stadium. In this way, the flexibility brAIn solution operates only within the permitted range of the heat pumps’ performance, helping the grid to manage unwanted surpluses or electricity shortages.

Stage two – installation of the smart battery storage brAIn

After tinkering with the technology and seeing the results it has brought for the stadium, the supplier decided to install a brAIn smart battery storage as well. It works in a similar way as the flexibility brAIn solution, providing non-certified ancillary services.

Here, too, optimization takes place fully automatically, using predictive algorithms supported by artificial intelligence, thanks to which this storage capacity is prepared for future developments in the power grid. When it expects a future surplus of electricity in the grid, due to unexpectedly sunny weather and the associated excessive production by solar panels throughout the country for example, it frees up battery capacity.

Thus, the role of storage is not to reduce electricity consumption itself, but to effectively shift the production and consumption of electricity over time according to the needs of the stadium and the entire power grid. The brAIn storage does not even need to be combined with solar panels, though that is always a plus.

Solution design and installation process

Since we have been monitoring and regulating the consumption of the football stadium for several months through the flexibility brAIn, we were able to quickly determine the most suitable battery storage capacity. We chose the same battery capacity as a recent installation in Bratislava's Tower 115 office building, 432 kilowatt hours. We designed it by analysing the stadium's electricity consumption, which is only around 4.1 gigawatt hours per year thanks to the energy-efficient heat pumps. We also looked at daily consumption diagrams to help us determine the optimal battery capacity.

In addition, we evaluated the reserved capacity and its maximum amount. One of the main tasks of battery storage brAIn is to monitor the excess reserved capacity, during football matches and various other events. It then dampens peaks in consumption and prevents the stadium from fines issued for exceeding the reserved capacity.

In this regard, combining the brAIn storage with the brAIn flexibility solution will also come in handy, as these technologies can also help each other. For example, when there is a risk of exceeding the reserved capacity, as just mentioned.

During the installation itself, we also had to solve the problem with the insufficient load-bearing capacity of the floor, which was not originally designed to accommodate a heavy storage. To strengthen it and accommodate more than 7-tonnes of equipment, in coordination with SEES, we had a metal structure manufactured and placed under the existing floor.

For this project, we also installed a special cooling system, which we placed in the back of the storage along its entire width. This is because the storage must be operated at temperature conditions from 20 to 35 degrees, otherwise performance is reduced. The batteries draw cool air through the entire rear surface and blow warm air through the entire front surface. The inverters have an intake at the bottom, with exhaust directed upwards.

What did the National Football Stadium gain?

Cost optimization and lower carbon footprint

In addition to optimising total energy costs, the brAIn flexibility and brAIn storage solutions also significantly reduce CO2e emissions by replacing traditional, predominantly fossil-fuel based, ancillary service providers in an emission free manner. According to the results achieved and data from our system, the National Football Stadium contributes to a savings of approximately 265 tonnes of CO2e per year, further reducing its already low CO2e emissions by a further 29 %.

Zero worries

The entire energy management for the National Football Stadium is taken care of by SEES. Since this is not our first joint project, the installation went without major complications. Thanks to SEES, the stadium has gained the opportunity to use modern green solutions, while we at FUERGY take care of the design, installation, management, service and maintenance of the repository, as always 🙂


Are you interested in a project like this? Then do not hesitate to contact us. We will be happy to prepare a tailor-made solution for you, with which you will save not only your costs, but also emissions.

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