West Group had installed a new HVAC system with 5 condenser units that caused noise complaints despite the headline dB(A) noise data suggesting there should not be a problem. They employed a noise consultant to devise a solution that was immediately implemented.
Ineffective HVAC silencers
Unfortunately, the silencers were completely ineffective as the consultants had failed to diagnose that the complaints were caused by a low-frequency hum and not by the overall dB(A) and, as a result of their (unfortunately all too common) incompetence, the Local Authority had to issue an abatement notice.
The company immediately stopped using the units but could not get a guarantee that the additional noise control measures suggested by the supplier would solve the problem. The EHO recommended that they contact INVC to consider alternative options.
Accurate noise complaint diagnosis
We diagnosed that the cause of the complaints was a low-frequency hum at the 53Hz – 57Hz blade pass frequency of the variable speed fans by analysing smartphone video clips and the audio recordings emailed by the EHO. The optimum solution was to design retrofit aerodynamic fan silencer modifications. These not only completely eliminated the problem tones (the major tone was reduced by 28dB) but also improved the system efficiency and the abatement notice was lifted.
The Facilities Manager, Bekki Jordan: “We sought expert advice on the noise problem as soon as it came to light, but unfortunately that advice proved to be both useless and costly. I want to take the opportunity to thank you for your help and support to allow us to get this ongoing issue resolved. The air conditioning has been running for two weeks now and we haven’t heard from either the council or the residents and the one resident who was spokesperson for the road said she can’t hear anything anymore…”
The whole project was carried out remotely, without a site visit, eliminating delays and travel costs.
