Acoustics and planning criteria

Noise from the Mechanical Plant

The replacement UDP Noise policies (ENV 6 & 7) are intended to protect noise sensitive properties from excessive noise levels and to contribute to the objectives of STRA 17 by reducing ambient noise levels where they exceed World Health Organisation (WHO) Guideline Levels. There is a distinction between areas with noise levels above WHO Guidelines (most of the City of Westminster), and areas below. The conditions also provide protection from structural transmission of noise and vibration within a property. It will often be appropriate to use more than one of these conditions for an individual proposal.

Noise sensitive properties are defined in the replacement UDP as: “all residential properties; educational establishments; hospitals; hotels; hostels; concert halls; theatres; broadcasting and recording studios.” However, the standard conditions refer to the nearest residential window, as this is by far the most common situation. You will need to alter these references in the rare cases when another noise sensitive use is the nearest affected. Applicants should contact the adjacent premises to ensure that this condition is complied with.

A preliminary noise report (acoustic and vibration report) is required with a planning application where a proposed development or change of use might affect noise sensitive properties.The conditions allow applicants the option of applying subsequently (after completion of the development) for a fixed maximum noise level. For this they will need to produce a further noise report. Selection of appropriate Noise Conditions is to be made on the advice of the Environmental Sciences Team (contact details below).

There are five sets of noise conditions. The first two sets (C46 and C47) are for plant and internal activity respectively, with the appropriate version to be selected according to whether the proposed development is in an area in which existing ambient noise levels exceed WHO Guideline Levels. If the locality of the proposed development exceeds WHO levels at any time of day or night, condition C46AB or C47AB is to be applied. Evidence of the 2003 Westminster Noise Study indicates that very few areas of Westminster can be expected to be below WHO Guideline Levels; in the few instances where this is the case, conditions C46BB or C47BBare to be applied. Part (4) in both C46 conditions and Part (3) in both C47 conditions provide the opportunity referred to in 5) above for applicants to apply to the City Council at a later stage for approval of a fixed maximum noise level.

A distinction is made within parts (1) and (2) of conditions in sets C46 and C47 between developments that will or will not contain tones or be intermittent. Tonal noise is relevant where sound emitted will include prominent levels of particular frequencies. These may be intrusive high-pitched or low-pitched noise. Intermittent sounds may be regular or irregular, but tend to be percussive.

‘Plant and machinery’ includes equipment such as: air conditioning; heating and chilling plant; lifts; etc. with associated ducting and outlets. ‘Internal activity’ covers noise such as that from amplified and unamplified music and human voices.

It will often be appropriate to impose two ‘hours conditions’ - one for plant operation (C46CB, adapted if necessary), and one for internal activity (C12), but the hours included may often be different in these two conditions.

C48AA ‘Vibration’ should be applied in all cases in which there is any possibility of structural transmission of noise and/or vibration through the structure of the proposed development to any other property.

C49 conditions are entirely new. C49AA is to protect new residential developments from existing noise in the vicinity. It should be applied to all residential applications that have been determined to be capable of achieving internal noise levels below those specified in the condition, despite being in areas in which existing ambient noise levels that are above the specified noise exposure levels. Where the specified maximum internal noise levels cannot be achieved, an application for residential development would not generally be approved (see also PPG24).

C49BA protects existing or proposed residential from transmission of noise or vibration within the same building, caused by a development or change of use. 14) C50AA ‘Noise from emergency plant and generators’ should be applied in all cases in which it is proposed that such equipment is installed.

These conditions are subject to frequent change. Please contact our Environmental Sciences Team on: 0207 641 3161, should you require further information.