Energy efficiency retrofit upgrade of a Gohl-KTK cooling tower while the data centre is in operation
Introduction
Keeping critical cooling infrastructure up to date without disrupting operations is one of the main challenges for modern data centres. At the Leibniz Supercomputing Centre (LRZ) in Garching, an existing Cofinair by GOHL-KTK evaporative cooling tower was successfully upgraded with the ECube Retrofit solution, delivering a significant improvement in energy efficiency and long-term reliability while the facility remained fully operational. Completed in just five working days, the project demonstrates how retrofit solutions can extend the life of existing cooling towers, reduce investment costs compared to full replacement, and provide a future-ready cooling system for mission-critical applications
Process Cooling
The Leibniz Supercomputing Centre (LRZ) in Garching operates the hot-water-cooled SuperMUC-NG (Next Generation), one of the most powerful supercomputers in Europe.
The data centre is far more than just a technical facility; it is the digital heart of Bavarian science:
- Data Hub: Manages user data and communication between Munich’s universities.
- Simulation Centre: Runs complex large-scale projects such as weather and earthquake models..
- Innovation Hub: Actively researches the future of computing.
The cooling principle is unique: the system is cooled with water. Reliability and operational safety are key factors.
SuperMUC-NG supports world-class international research in fields ranging from astrophysics and life sciences to environ-mental science.
Total cooling capacity : 16,750 kw
| Unit | Quantity | Inlet water temperature | Outlet water temperature |
|---|---|---|---|
| VK 5/77/7 | 6 | 45 °C | 30 °C |
| DT 5/ 77 Z XL | 1 | 20 °C | 16 °C |
Successful ECube RETROFIT At the Leibniz-Rechenzentrum Garching
In October 2025, an existing Gohl cooling tower was systematically modernised.
The aim of the project was to bring the unit up to the latest energy and technical standards – with minimal downtime and whilst the data centre remained in operation..
Initial situation
At its Garching site, the LRZ operates six closed cooling towers and one open cooling tower with a total cooling capacity of 16,750 kW. The cooling infrastructure supplies, among other things, water-cooled high-performance computers such as the SuperMUC-NG.
Project focus: retrofit instead of replacement
The focus was the conversion of a Gohl-ktk evaporative cooling tower of type VK 5/77/7 (SNr. GO-001584). The existing fan chamber was completely dismantled and replaced with the E-CUBE Retrofit, whilst the existing wet room continued to be used.
Advantages of this approach:
- cost-effective modernisation instead of full re-placement
- short conversion time
- use of existing infrastructure
- technical and energy-efficiency upgrade
Technical implementation
The work was carried out over five working days. Despite the confined space and a working height of 37 metres, the existing fan chamber was dismantled and the E-CUBE was prepared on the ground, then hoisted onto the roof by crane and connected to the wet room after the connection surfaces had been cleaned.
Quality and operational reliability
Particular attention was paid to sealing all water-carrying areas and the precise structural integration of the E-CUBE. Any necessary adjustments to the internal air intake plates were carried out directly during installation, to ensure a permanently secure air flow.
The final stages of the work included final bolting, silicone sealing, cleaning the cooling tower base and a final inspection.
Added value for the operator
The E-CUBE retrofit has sustainably optimised the cooling tower for future operation. The new fan chamber provides the basis for:
- Improved energy efficiency
- Enhanced operational reliability
- Future-proof cooling infrastructure
- Optimisation of maintenance and service conditions
Conclusion
The project at the Leibniz Supercomputing Centre in Garching demonstrates how existing cooling tower systems can be cost-effectively modernised and kept in operation in the long term through targeted retrofitting measures. The conversion to the E-CUBE standard confirms the solution’s suitability for demanding data centre environments.
