25 March 2026
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Image: Structural underside of the elevated cooling installation prepared for acoustic testing and airflow validation
STULZ, recently teamed-up with Merford, to establish a new benchmark for validated noise performance in data centre cooling. The companies conducted a unique acoustic test on a newly developed chiller for a project in Valeggio sul Mincio, Italy, which was conducted under realistic operating conditions using a fully validated measurement methodology.
As data centre power densities rise, cooling system design is expanding beyond capacity and energy efficiency to include another critical factor – noise. Larger and more powerful cooling systems can significantly impact surrounding environments, particularly when facilities are in urban areas with strict noise regulations. The evaluated project had to comply with maximum night-time noise limits of 80.2dB(A) and meeting this requirement demanded that acoustic considerations be incorporated into the early stages of equipment design.
“The challenge was not only to guarantee efficient cooling but to comply with extremely strict noise limits, explained Davide Mazzi, head of the STULZ Application Team at STULZ SpA. “The installation is located on a rooftop in a densely built urban environment. Our task was to deliver the required performance without disturbing the surroundings and without compromising the operational reliability of the data centre.”
Comprehensive acoustic validation of large cooling equipment is rarely conducted, however, STULZ and Merford developed an integrated noise attenuation system designed specifically for this chiller configuration. The acoustic measurements were conducted according to EN ISO 9614-2:1997, which determines sound power levels using sound intensity measurements.
Prior to testing, a detailed environmental analysis was carried out. Using a three dimensional acoustic model in SoundPLAN, which is specialised software for sound propagation calculations based on ISO 9613-2, the team optimised the test configuration. Background noise levels had to be at least 10dB below the sound emitted by the chiller itself and at the production site a measurement location was established. Supporting equipment such as transformers, boilers and pump skids were deliberately positioned to ensure their operation would not interfere with the measurement process.
Two different noise attenuation concepts were evaluated, both comprising steel frame structures surrounding the chiller with integrated acoustic attenuators to mitigate both airborne and structure borne noise. The first configuration served as a baseline to deliver broad spectrum noise reduction, while the second incorporated additional acoustic optimisation and enhanced source control measures to further reduce total sound power levels. While this configuration introduced additional weight and structural complexity, it led to demonstrably greater noise reduction.
To verify the effectiveness of the system, engineers measured the chiller’s sound power level both with and without the attenuation structure in place. This comparative approach enabled the team to objectively quantify the noise reduction achieved and confirm regulatory compliance.
“We were delighted to find that the chiller equipped with the developed attenuation system successfully met the stringent noise requirements, concluded Davide.
“This project demonstrates that data centre cooling and acoustic compliance can be achieved simultaneously when engineering, acoustic design and validation are approached as an integrated process. As data centres continue to expand into urban environments, such integrated approaches are likely to become essential for balancing performance, sustainability and community impact.”
STULZ has produced a video showing how the test to validate the acoustic performance of the data centre chiller was carried out. To watch it visit: https://youtu.be/EkFgFAxilTQ
