Smart Cooling Control

As a municipal utility with around 1,100 employees, Stadtwerke Karlsruhe supplies over 400,000 people with electricity, natural gas, district heating, and drinking water. This includes the Karlsruhe GartenCarée complex, whose cooling system is operated by the utility. In addition to residential flats and offices, the building complex also houses a data centre, medical practices, a shopping parade and dining establishments.

The GartenCarée cooling system consists of three absorption chillers powered by environmentally friendly district heating or process waste heat from a nearby refinery, as well as a compression chiller with two compressors and a cooling tower. “In terms of the energy consumption of our system, we were more or less flying blind,” recalls Jürgen Weiß, Team Leader for Construction Management and Technology at Stadtwerke Karlsruhe, describing the situation before the solution was introduced. “At the end of the year, all we could see was how many megawatt hours of cooling we had produced and how much electricity and district heating we had consumed to do it. No more, no less.”

Greater Transparency and Efficiency in Cooling Production

The utility set out to identify and realise energy-saving potential. “To this end, we installed an automated energy system management solution with the provider, enabling improved component control and detailed monitoring. As a result, all energy flows are now visible in detail and optimisation can be directly implemented and analysed. The level of transparency we’ve achieved is a major advantage,” says Weiß. Parameters such as flow rates of chilled and cooling water are measured and evaluated to assess the economic viability of operating the absorbers or using free cooling, depending on the outside temperature. A typical finding: pumps running constantly at 100 percent flow rate, even though 60 percent or less may suffice depending on conditions, represent significant efficiency and savings potential.

A major issue in cooling production is that pumps and cooling towers often consume as much electricity as the chillers themselves, without this being recognised. Furthermore, optimisation of electricity demand often takes place only at the component level and frequently only for a predefined operational state from the planning phase. This state typically occurs during fewer than three percent of all operating hours. The result is unnecessary electricity consumption during the majority of operating time. Achieving efficiency gains through better interaction between components is the speciality of Faktor4Solutions.

20 Percent Less Electricity, Five-Figure Cost Savings

The intelligent software from Faktor4Solutions considers the operation of all components relevant to cooling technology and thus their combined energy consumption. The solution uses digital twins of the components and the cooling system itself to calculate, in real time or based on specific conditions, how each component must behave to achieve maximum system efficiency. As a result, chillers and all auxiliary equipment are no longer deployed in a fixed sequence (base and peak load), but rather based on efficiency – depending on weather conditions and the required output – and are controlled via standardised protocols by the system management. This enables the solution to ensure the most efficient system operation in every load scenario.

Absorption Chiller Systems, Cooling Centre, Synus Building (© Factor4Solutions GmbH)

That this applies to their own system became apparent to Stadtwerke shortly after the test phase was completed. “In just those six months, we already saved over 20 percent of annual electrical energy consumption – a financial saving in the five-figure range,” says Weiß. And that is likely just the beginning, as there is still significant optimisation potential across the full year. The system’s components interact differently throughout the seasons, depending on cooling demand and ambient temperatures. Weiß is confident: “During the other six months, the system was still running under our traditional control logic, meaning we can save even more energy. According to Faktor4Solutions’ calculations, over 40 percent.”

100 Percent Operational Reliability

Another key benefit for Stadtwerke is the fact that the system and software are continuously monitored, reviewed and optimised by the provider, even after installation. Weiß explains: “We do monitor the system ourselves, but having the cooling technology specialists operate it via AI-supported remote maintenance – and notify us immediately if anything goes wrong – is a major advantage.” By using digital twins and real-time comparison of operating data, Faktor4Solutions can even alert customers in advance to deviations and potential failures, enabling them to be prevented proactively.

“Ensuring operational readiness at all times is particularly important for us because we are contractually obligated to deliver cooling. At GartenCarée, we’re not just supplying office and residential units – we’re also cooling a data centre,” adds Weiß.

Asked about how the implementation phase went, Weiß reports: “In collaboration with the service provider that maintains our measurement and control technology, we provided the necessary data points required by the provider to set up the system. Factor4Solutions, based in Berlin and managing the solution remotely from there, had previously informed us of which data points were needed – including flow rates, temperatures, and thermal and cooling energy meters. Within a day, the software was configured, and the first analysis was ready within four to six weeks. From the results, we could identify which additional data points were required, and the system was fine-tuned accordingly.” This straightforward setup makes the solution attractive across sectors wherever cooling systems are used.

Fast Payback Supports Further Expansion

Even after the test phase, it was clear: “All I had to do was compare annual consumption and cooling production to the previous year to see the clear efficiency improvement and energy savings,” says Weiß. And when it comes to return on investment, the team leader is very satisfied. “The annual cost of working with the cooling technology specialists is offset by the energy savings within just the first five months of each year.”

It’s no surprise then that Stadtwerke Karlsruhe is considering expanding the collaboration. “We’re already having another system managed by Factor4Solutions. And we operate additional cooling systems that could potentially be suitable,” says Weiß. Since the solution can be integrated into almost any system, there’s a strong chance that the AI solution can also deliver the desired insights and savings elsewhere.