Good Practices on the Control of Noise from Electrical & Mechanical Systems

Planning against Noise Problems


Positioning of Equipment


The installation position of equipment is of critical importance in determining the level of noise to be transmitted to the nearby noise sensitive receivers (e.g. residential buildings or schools).

Where practicable, the equipment should be placed in a plant room with thick walls or at a location with much greater distance from the receiver or behind some large enough obstruction (e.g. a building or a barrier) such that the line of sight between the receiver and the equipment is blocked.

Design of residential buildings should avoid locating area of noise sensitive uses (e.g. bedrooms) next to noise sources (e.g. machine rooms, lift shafts, etc.). Instead, other areas of less noise sensitive use (e.g. corridors, kitchens, bathrooms, etc.) may be assigned to separate area of noise sensitive use from noise sources. This can avoid some future noise problems and possible costs for any subsequent noise control measures.

If noisy equipment has to be placed near a receiver due to spatial or other constraints, appropriate noise control measures should be considered.


Selection of Quiet Equipment

Though quieter equipment may generally be more expensive. It is however, more economical in the long run to buy quieter equipment (e.g. silent type chillers, water cooling towers, or pumps) than to carry out abatement work for mitigating excessive noise generated from noisy equipment. Most equipment has a range of readily available noise control devices that are able curb down the noise. It is advisable that noise levels specification is included when ordering new equipment. This allows the equipment suppliers to select appropriate equipment and optional noise control devices to suit the acoustic requirements.


Proper Implementation of Noise Mitigation Measures

If noise mitigation measures are required, it is important that they are implemented properly. For example, gaps at noise barriers and enclosures should be sealed up to prevent noise leakage, vibration isolators should be allowed to perform at their designed deflection ranges without being locked up or being short-circuited by other transmission paths. Examples are shown in Section 5.5 for reference.


Scheduled Maintenance

In order to prevent increasing noise produced by existing equipment, it is necessary to put in place a regularly scheduled equipment maintenance programme so that equipment is properly operated and serviced in order to maintain controlled level of noise and vibration. Maintenance may include lubricating moving parts, tightening loosen parts, replacing worn-out components or inspecting equipment alignment, etc. Vibration measurements at various frequencies may help to detect causes of excessive vibration or noise of a machine. A guide to vibration identification is given in Appendix XIII.