Wien Energie: Reducing forward temperature by 5 degrees

For four years, Wien Energie has been optimizing various heating grids by working with Gradyent’s Digital Twin Platform, and by doing this, has decreased heat loss and CO₂ emissions and saved operating costs. In April 2023, Wien Energie and Gradyent started the heat pump optimization project to lower the temperature of the heating network in Oberlaa.

Challenge

Wien Energie plans to be net zero by 2040 regarding district heat. The target state includes a substantial share of heat pumps and geothermal. In order to make this possible, the entire Wien Energie grid requires a major transformation. Digitisation is recognised as a key enabler and therefore Wien Energie follows an open innovation approach including transformation and innovation of its heating systems.

Solution

In 2021, Gradyent participated in the Wien Energie Innovation Challenge. For this competition, within 6 weeks Gradyent developed a Digital Twin for one of the nearly 600 secondary networks of Wien Energie to showcase the value of temperature optimization for the grid and won the competition.

With the real-time Digital Twin Platform, Gradyent created a digital copy of the complete grid that runs in real-time, combining geographical, weather, and sensor data with physics-based models and AI. The Digital Twin provided insights for the entire system – even for places where no data or smart meters were available. After this successful pilot, Wien Energie and Gradyent expanded their collaboration and developed Digital Twins of other secondary networks to scale up the savings and impact.

Seeing the results of Digital Twin integration, Wien Energie saw a lot of potential in this approach: if rolled out to the 20 largest secondary networks, the company could save up to 4,000 MWh of heat.

Results

Lowering the temperature and heat loss and saving operational costs

During the four years of temperature optimization, Wien Energie has decreased heat losses and CO₂ emissions and saved operating costs. For instance, as the result of Digital Twin integration, the temperatures were dynamically reduced on average by 4-5°C, depending on the network.

Besides the direct savings, the security of supply could be increased, and valuable insights could be delivered on the network showing a detailed potential on return temperature, hydraulics, and pump efficiencies.

By building the Digital Twin, Wien Energie gathered valuable insights about the behavior of their network. Anomalies, alerts, and maintenance as well as potential savings in networks including heat pumps have been outlined leading to a deeper understanding of the Digital Twin value at Wien Energie.

Dynamic temperature optimization in action

Forward temperature could be lowered to ~65 °C in summer while maintaining security of supply and considering increased pump costs vs. decreased heat loss. One client station needs hot water with >70 °C once a month to treat legionella – the Digital Twin accounts for this by automatically increasing the required supply temperature for this single user. After the legionella treatment, the temperature requirement is relaxed again.

Expanding to heat pump optimization to increase efficiency and added value

Gradyent and Wien Energie have been cooperating since April 2023 under the DeRISK-DH initiative, funded by the Climate and Energy Fund and co-coordinated by AIT Austrian Institute of Technology GmbH. In this context, one secondary network is considered – connected to the primary heating grid (“Lastverteiler”) but also partly supplied by a heat pump. Thanks to high sensor coverage at the user stations, the rollout of the user monitoring module was made possible.

Since going live in August 2024, Wien Energie can now directly identify user stations with unfavorable return temperatures, allowing them to either address these users or prioritise technical maintenance on the respective installations. As a result, the company is seeing cost savings as less pump energy is required when the temperature difference at the substations is increased. Building on this progress, heat pump optimization is scheduled to go live by the end of summer 2025.