May 2024 – Serbian Energy Scouts reduce electricity costs by more than 38% by installing frequency regulators on circulation pumps

The Zumtobel Group is an Austrian based company in the field of lighting. They develop and produce professional lighting systems for an international market. Beijing International Airport, the Allianz Arena in Munich and the Guggenheim Museum in Bilbao – all illuminated by Zumtobel lighting solutions. Zumtobel employs 5,500 employees worldwide, 900 of whom work at the Niš plant and R&D center in Serbia. The modern 40,000m2 industrial complex was built in 2018 and is certified according to ISO 50001 (energy management). So for Zumtobel’s Energy Scouts Marina Mijić, Aleksandra Maksimović and Milan Mitić, there were no low-hanging fruits to harvest for their energy efficiency practical project.

They took a logical approach to finding a practical energy efficiency project: Let’s find out where most of the  energy is used! The most significant energy consumer in the factory is the utility block, which includes the building’s heating and cooling facilities, air conditioning, compressor substation and other common technical systems. The biggest energy consumer among them is the cooling and air conditioning plant, which consists of three CIAT chillers with a total cooling capacity of 3 MW, so the Energy Scouts used the monitored data and analyzed the energy consumption of the chiller system.

They discovered that although the chillers were running at 100% nominal power 24 hours a day during the summer season, the pumps could actually be running at lower speed and using less energy while simultaneously providing the same flow of water needed for the chillers. The solution to optimize the chiller plant system became clear: they needed to install frequency regulators on the circulation pumps. They tested it first on one circulation pump with 22kW nominal power. By fine-tuning the frequency and reducing the engine speed (RPMs), along with the system parameterization and adjustment of the required flow, they were able to reduce the active power of this circulation pump to 13.5kW on – thus reducing energy consumption by 38%.

After some test period and more measurements and analysis, they defined a CAPEX project to optimize the whole cooling utility by installing 4 more frequency regulators on the rest of the pumps and gain a benefit of 123 MWh annual energy savings and corresponding 111 tons of CO2 emission savings per year.



  • Industry sector: production of LED lighting and lighting equipment
  • Energy source: electricity
  • Energy savings potential: 123 kWh/year
  • CO2 savings potential: 111 tons CO₂/year
  • Potential cost reduction: 19,699 €
  • Investment costs: 15,760 €
  • Payback period: 10 months
Cooling utility with 3 CIAT chillers with a total cooling capacity of 3MW (left) and circulation pumps with installed frequency regulators for each chiller (right (©Zumtobel)
BMS system for monitoring and setting the chillers plant system – two chillers for cooling the facility (left) and one chiller for ventilation cooling (right) (©Zumtobel)
Power consumption after setting and fine-tunnig one frequency regulator on 22kW circulation pump: the power reduced to less than 13.5kW (©Zumtobel)
Energy Scouts Milan Mitić, Marina Mijić and Aleksandra Maksimović analyzing and adjusting frequency regulators for circulation pumps, with monitoring through the BMS system (©Zumtobel)
Energy Scouts Milan Mitić, Marina Mijić and Aleksandra Maksimović after setting new parameter for frequency regulators for circulation pumps (©Zumtobel)