Sound attenuating measures for data centre cooling units

Cooling units positioned on the roof of a data centre were emitting an excessively high noise level. This caused noise nuisance to local residents. Alara-Lukagro designed and delivered soundproof measures, including acoustic walls and acoustic louvres.

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Noise measurements

A data centre owned by Mobistar, one of the largest players on the telecoms market in Belgium, has diverse cooling units on the roof that were emitting too much noise. Mobistar enlisted the services of the consultancy firm Arcadis, to perform noise measurements and issue an advisory report.

Acoustic measures for cooling units

It soon became clear that the existing chillers had to be replaced and ISB Ventilatie was contracted to do so. However, the strict acoustic requirements meant that the new units also needed additional noise reduction measures. First it was proposed that round silencers be fitted to the cooling units and Alara-Lukagro and DOX Acoustics were involved to elaborate the idea.

Alternative solution proposed

Following extensive calculations, Alara-Lukagro, in close consultation with DOX Acoustics, presented an alternative solution that responded more effectively to Mobistar’s wishes. Mobistar selected the alternative solution put forward by Alara-Lukagro. DOX Acoustics coordinated the project, in which Alara-Lukagro was fully responsible for the implementation: from design and engineering to production and installation.

Effective and efficient solution


The acoustic measures were designed in two parts. For the two cooling units on steel structures in the existing sheet pile cladding:

  • 28 acoustic louvres for the air inlet
  • Two sets of three splitter silencers for the air outlet
  • Acoustic panels as a roof

For the three other cooling units:

  • U-shaped acoustic wall with a total length of 51.3 metres and a height of 4.1 metres
  • For the latter’s installation a steel structure was produced by Alara-Lukagro in accordance with EN 1991-1-4, Belgian National Annex (related to wind load) and¬†Eurocode 3, 1993-1.
Sound attenuating measures cooling units
Geluiddempende maatregelen koelunits
Geluiddempende maatregelen koelunits
Sound attenuating measures cooling units
Sound attenuating measures cooling units

The advantages of this solution

Following extensive calculations, Alara-Lukagro, in close consultation with DOX Acoustics, presented an alternative solution that responded more effectively to Mobistar’s wishes.

The advantages Alara-Lukagro achieved for Mobistar with this solution are:

  • More efficient in terms of cost, by using fewer materials.
  • Acoustic measures for cooling units
  • More compact in terms of external appearance, by replacing the high, round silencers with compact splitter silencers and absorbing panels.
  • Inconspicuous, by fitting the same sheeting to the noise reduction measures as the building.
  • Minimum pressure loss: maximum 35 Pa with an air quantity of 284,000 m3 per hour.
  • Lightweight: the solution was below the maximum weight as it was made from aluminium.

Thanks to its comprehensive knowledge of sound, extensive tests and advanced calculation programmes, Alara-Lukagro can always design the most effective and efficient solution for complex noise control projects.

Result and experience

It resulted in a 35 dB sound attenuation of the chillers in relation to the environment. This easily achieved the proposed noise requirements.

ISB Ventilatie, main contractor and supplier of the new chillers for Mobistar, recounted its experience of working with Alara-Lukagro and DOX Acoustics.

A reference to be proud of!

“In 2013 kregen we van Mobistar de bestelling voor de akoestische aanpassingswerken. Dit was een complex en gevoelig project, waarbij akoestisch strenge eisen werden gevraagd. De samenwerking en projectbegeleiding met Alara-Lukagro en DOX acoustics verliep zeer correct en professioneel. De gevraagde resultaten werden ruimschoots behaald.”

ISB Ventilatie, hoofdaannemer

More information?

Are you facing a similar challenge?

Contact us with your questions and we will be delighted to advise you on a suitable solution for your project.

Ronald van Ditshuizen Account Manager +31 (0) 184 820 764
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