Noise Criteria
Let us first consider which types of development require protection from noise, which are considered noise tolerant, and the usual time periods in concern.
Here are some commonly used terms when we refer to noise criteria.
The term "Noise Sensitive Receiver", often abbreviated as NSR, refers to premises that is used for purposes sensitive to noise and requires protection. Examples of noise sensitive receivers are domestic premises, hotels and hostels, educational institutions and hospitals and clinics. Please click on the following diagram to see the enlarged photos.
Noise Sensitive Receiver
[Photo of Noise Sensitive Receiver - Domestic Premises]
[Photo of Noise Sensitive Receiver - Hotel]
[Photo of Noise Sensitive Receiver - Educational Institution]
[Photo of Noise Sensitive Receiver - Hospital]
Non-NSRs include multi-storey car parks and markets, godowns, community uses such as sports complexes and commercial centres or premises. Please click on the following diagram to see the enlarged photos.
Noise Tolerant Uses
[Photo of Noise Tolerant Uses - Multi-storey Car Park]
[Photo of Noise Tolerant Uses - Multi-storey Shopping Centre]
A day is often divided into three time periods as indicated below :
| Day | 0700 to 1900 hours (7:00 a.m. to 7:00 p.m.) |
|---|---|
| Evening | 1900 to 2300 hours (7:00 p.m. to 11:00 p.m.) |
| Night | 2300 to 0700 hours (11:00 p.m. to 7:00 a.m.) |
[Photo of day]
[Photo of evening]
[Photo of night]
The Type of Area Containing NSR refers to the characteristics of the area in which the NSR is located. The table below indicates the types and contains some typical examples. There is a mimic photo for each of the examples. Click on the mimic photo for enlarged viewing.
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Type of Area Containing NSR |
Examples |
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|---|---|---|---|---|---|
| (i) | Rural area, including country parks or village type developments |
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| (ii) | Low density residential area consisting of low-rise or isolated high-rise developments |
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| (iii) | Urban area |
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| (iv) | Area other than those above |
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The term "Influencing Factors", abbreviated as IF, refers to industrial areas, major roads or areas that are situated within the boundary of the Hong Kong International Airport. Their presence in the vicinity of a NSR may dominate the ambient or background noise there in such a way that it is impractical to stipulate too low a noise limit for either planning or control purpose.
The term "industrial area" refers to an area which consists of a number of factories or industrial establishments; or an establishment which is having industrial operation or operations of a significant scale.
A "major road" means a road which has a heavy and generally continuous flow of vehicular traffic and, in normal circumstances, means a road with an annual average daily traffic flow in excess of 30,000 vehicles. Where a major road has an unusually low traffic flow rate (less than 300 vehicles per hour) at the time of day under consideration, it shall not be considered as an IF at that time.
The term "Degree to which NSR is affected by IF" refers to how the NSR is being affected by the IF. It can be either :
- not affected, or
- indirectly affected, or
- directly affected.
For "directly affected", the NSR is at such a position that noise generated by the IF is readily noticeable at the NSR and is a dominant feature of the noise climate of the NSR.
"Indirectly affected" means that the NSR is at such a location that noise generated by the IF, whilst noticeable at the NSR, is not a dominant feature of the noise climate of the NSR.
For "not affected", the NSR is at such a location that noise generated by the IF is not noticeable at the NSR.
The "Area Sensitivity Rating", abbreviated as ASR, is a rating of the area in which the NSR is located. The ASR can be either A, B or C and is derived from the following table after knowing the Type of Area Containing NSR, any presence of IF, and "Degree to which NSR is affected by IF". Please click on the demo button to read the details.
[Animation introduces Area Sensitivity Rating]
Noise Criteria for Control
Noise from Percussive Piling
Percussive piling is not allowed during the Prohibited Period. (The Prohibited Period is from 7:00 p.m. to 7:00 a.m. on weekdays and any time on public holidays including Sundays.)
A valid Construction Noise Permit(CNP) issued by the Environmental Protection Department is required for the carrying out of percussive piling during the restricted hours, i.e. 7:00 a.m. to 7:00 p.m. on weekdays not being a public holiday. Depending on the noise, a CNP holder may carry out percussive piling for a total duration of 3 hours, 5 hours or 12 hours during the restricted hours each day.
Table 1 of the Technical Memorandum on Noise from Percussive Piling showing Acceptable Noise Levels (ANLs) for various types of NSR is reproduced as follows :
[Table of Acceptable Noise Levels for various types of NSR containing in the Technical Memorandum on Noise from Percussive Piling]
The ANLs shown in the above table are to be reduced by 10 dB(A) for NSRs such as hospitals, medical clinics, educational institutions, courts of law or other NSRs which are considered to be particularly sensitive to noise. Any associated noise measurement shall be made in Leq(5 min).
For further details, please refer to the Technical Memorandum on Noise from Percussive Piling by clicking here.
For details of the legislative control on percussive piling, please click here.
Noise from Construction Work other than Percussive Piling
This type of work is also called general construction work.
The term "Designated Areas", abbreviated as DAs, is a special term used in the control of noise from general construction work. DAs are built up or populated areas. Because DAs contain considerable number of NSRs, noise affecting these areas warrants a tighter control. Non designated areas are not built up areas and may include commercial districts, industrial zones and similar less noise sensitive uses.
Demarcation of DAs can be viewed on the EPD website. For accessing it, please click here:
Some general construction work employ powered mechanical equipment (PME), i.e. machines driven by electricity, compressed air or hydraulic means. In other situations; the construction work may involve hammering and erection or dismantling of formwork or scaffolding.
Within Designated Areas, powered mechanical equipment (PME) is categorized into Specified Powered Mechanical Equipment (SPME) and non-SPME. The SPME are generally noisier and warrant tighter control.
The following are SPME:
- Hand-held breaker
- Bulldozer
- Concrete lorry mixer
- Dump truck
- Hand-held vibratory poker
Within DAs, three types of general construction works are particularly noisy warrants tighter control. There are called Prescribed Construction Work (PCW):
- Erection or dismantling of formwork or scaffolding
- Loading, unloading or handling of rubble, wooden boards, steel bars, wood or scaffolding material
- Hammering
There are two sets of noise criteria or Basic Noise Levels, in dB(A), abbreviated as BNLs:
BNLs contained in the Technical Memorandum on Noise from Construction Work in Designated Areas
[Table of Basic Noise Levels containing in the Technical Memorandum on Noise from Construction Work in Designated Areas]
The above table is used in the assessment of CNP applications for construction work using one or more of the SPME in construction sites located within DAs.
BNLs contained in the Technical Memorandum on Noise from Construction Work other than Percussive Piling
[Table of Basic Noise Levels containing in the Technical Memorandum on Noise from Construction Work other than Percussive Piling]
This table is used in the assessment of CNP applications for construction work using any PME in construction sites located within Non-DAs; and for construction work using PME other than SPME in construction sites located within DAs.
The BNLs are modified to take into account the duration of the construction work and any CNPs hitherto issued for the same sites to give a set of Acceptable Noise Levels, abbreviated as ANLs. Any associated noise measurement shall be made in Leq(5 min).
Noise from the construction sites is then predicted using standard acoustical principles. If the predicted noise does not exceed the ANLs, CNP will be issued. Otherwise, CNP will not be issued.
For further details, please refer to the Technical Memorandum on Noise from Construction Work in Designated Areas and the Technical Memorandum on Noise from Construction Work other than Percussive Piling.
For details of legislative control on general construction works other than percussive piling, please click here.
Noise from Constructing or Decommissioning of Designated Projects under the Environmental Impact Assessment Ordinance.
Apart from the above controls on construction activities under the Noise Control Ordinance, there are also noise criteria for carrying out daytime construction activities during the construction or decommissioning phase of designated projects under Environmental Impact Assessment Ordinance. These noise criteria shall be met as far as practicable. All practicable mitigation measures shall be exhausted and the residual impacts minimized.
| Noise Standards | Noise Sources | |
|---|---|---|
| 0700 to 1900 hours on any day not being a Sunday or general holiday Leq (30 mins) |
1900 to 0700 hours or any time on Sunday or general holidays |
|
| Uses | 75 | (See Note 3) |
| All domestic premises including temporary housing accommodation | ||
| Hotels and hostels | 75 | |
| Educational institutions including kindergartens, nurseries and all others where unaided voice communication is required | 70 65 (During examinations) |
|
Notes:
- The above standards apply to uses which reply on opened windows for ventilation.
- The above standards shall be viewed as the maximum permissible noise levels assessed at 1 m from the external facade.
- The criteria laid down in the relevant technical memoranda under the Noise Control Ordinance for designated areas and construction works other than percussive piling may be used for planning purpose. A Construction Noise Permit (CNP) shall be required for the carrying out of the construction work during the period.
Noise from Places other than Domestic Premises, Public Places or Construction Sites
This kind of noise is commonly known as noise from industrial/commercial premises or simply industrial/commercial noise. Examples of sources of this type of noise are factories, restaurants, electric sub-stations and similar stationary noise sources.
This kind of noise is controlled under a system of Noise Abatement Notices. The noise under investigation is measured and corrected for any special intrusive characteristics such as tonality, impulsiveness and intermittency in accordance with the Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites issued under the Noise Control Ordinance(NCO).
If the noise is found to exceed statutory limits, a Noise Abatement Notice (NAN) will be issued to the relevant party or parties requiring them to abate the noise to within the statutory limits within a given time period.
Table containing Acceptable Noise Levels (ANLs) in dB(A) of the Technical Memorandum is reproduced as follows :
[Table of Acceptable Noise Levels containing in the Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites]
The values in the above table apply to airborne noise. In case of noise transmitted primarily through the structural elements of a building or buildings, the appropriate ANL is 10 dB(A) less than the values shown in the table. This kind of noise is known as structural-borne noise. For examples, vibration from pumps and pipings may cause noise to be transmitted through the building structure.
The issue of ASR has been discussed in an earlier part of this Module. For a recap, please click here. The Technical Memorandum contains a special provision on ASR. The provision is as follows :
"Any NSR shall, irrespective of the above table, be assigned an ASR of C if it is within 100 m of a zone designated as Industrial or Industrial Estate on a statutory Outline Zoning Plan, or an ASR of B if it is between 100 m and 250 m from such a zone, except in cases where the above table indicates an ASR of C.
For further details, please refer to the Technical Memorandum by clicking here.
For details of legislative control on noise from places other than domestic premises, public places or construction site, please click here.
Noise Criteria for Planning
The basic role of planning against noise is to provide an environment whereby noise perceived at noise sensitive uses satisfies the appropriate noise criteria.
The principle is to ensure that:
- new noise sensitive uses are located where they will not be exposed to excessive noise levels;
- new noise emitters are located away from existing, committed or planned sensitive uses; and
- where other constraints do not permit either of the above, noise reduction designs should be incorporated into the noise emitters at the earliest stage of planning. Where a completely acceptable noise exposure cannot be obtained at the noise sensitive uses, acoustic insulation should be provided.
For more details on mitigation measures, please click here
Noise standards for planning purposes are set out under the Environmental Impact Assessment Ordinance Technical Memorandum (EIAO-TM).
[Table of noise standards for planning purposes]
The "Environmental Guidelines for Planning in Hong Kong", which form parts of the Hong Kong Planning Standards & Guidelines (HKPSG) published by the Planning Department, also provides guidelines on planning on most environmental issues.
For further details on the Hong Kong Planning Standards & Guidelines (HKPSG), please click here and you will be directed to the website of the Planning Department.
For more details on planning, please click here.