With space in commercial buildings at a premium and the distance between commercial and residential buildings narrowing, noise control is playing a more prominent role than ever before. Andy Milkins, General Manager at Acoustica – part of the Elta Group – a specialist in the control of industrial and environmental noise and vibration – discusses what considerations come into play when exploring noise reduction methods.
Decoding Acoustic Regulations
Despite the growing importance of noise control, Building Regulations for England, Wales, Scotland and Northern Ireland are yet to include mandatory requirements for the acoustic performance of commercial buildings. Sound insulation guidance for commercial buildings is instead covered within BS 8233:2014, which deals with the control of noise from outside the building, noise from plant and services within it, and room acoustics for non-critical situations.
As many engineers will be aware, BS 8233 is a code of practice that is intended for use by non-specialist designers and constructors of buildings and those concerned with building control, planning and environmental health. The code suggests appropriate criteria and limits for different situations, which are primarily planned to guide the design of new or refurbished buildings undergoing a change of use.
The British Council for Offices (BCO) Guide to specification 2009 also provides essential acoustic guidance for external noise intrusion, internal noise and noise from building services. But in the absence of any real mandatory requirements, which noise reduction methods need to be considered?
In practice, the acoustic needs of specific commercial buildings go a lot further than the guidelines suggest. There are many influential factors that come into play, meaning that every application needs to be looked at separately. The practical measures for an office, bank, shop, court room or distribution centre, for example, are all very different and must be managed by varying acoustic attenuation methods if the exacting demands are to be achieved.
Retail spaces for example, vary enormously in their nature; from small individual shops to large department stores to open plan shopping centres to industrial warehouse style retail premises. The type of retail space will affect the desired and acceptable acoustic properties, which in turn will dictate what solutions are used. Additional considerations need to be added into the mix when residential and commercial co-exist in the same structure, such as apartments sitting above retail facilities.
All things taken into account
Effective acoustic management can only be achieved when all of the specific considerations are taken into account, which include:
- Sound Insulation; the passage of sound between buildings or from street to a room, from room to room or between floors.
- Reverberation; a re-echoed sound that is persistent after its source has stopped, which is caused by reflection of the sound within a closed space. Reverberation can be controlled with the specification of suitable wall, floor and ceiling finishes. It is crucial that the reverberation of sound is controlled in spaces where speech intelligibility is important, such as in meeting rooms.
- Ambience; correct specification of materials can significantly affect the acoustic performance of the space and the ambience that is created. This is particularly the case in large open spaces such as car show-rooms, in areas with large hard surfaces and in stores where the quality of music and/or PA system is important.
- External noise intrusion; any external noise in your surroundings created by people and the nearby environment.
Selecting the correct attenuating solutions
Within the HVAC industry, the focus is on mechanical powered ventilation and the management of the sound propagation. Over the last few years considerable product development has taken place; partly driven by product regulations and partly by consumer demand specifically for energy consumption and environmental acoustic performance. This requirement has ensured an increased level of acoustic attenuation has been incorporated into many of the primary product sound sources. However in many cases this isn’t sufficient and additional attenuation is required in the form of Cylindrical and Rectangular duct attenuators, Acoustic Louvres and Acoustic Enclosures.
The demand for acoustic attenuation is increasing through integration into mechanical noise sources, supplementary attenuation methods within a ducted system, acoustic barriers, noise source enclosures or absorption within the fabric of the building. Whilst the preference for attenuation is to be built in at the building design stage, it is increasingly common for it to become a requirement further down the line. This allows for full testing to be practically carried out in the actual environment, as well as for real acoustic influencing factors to be accounted for.
The current proximity of residential dwellings demands that the commercial noise impact is also compliant with the environmental legislation of the local authority. This is a challenging task in many cases, but one that can be overcome with a combination of attenuation techniques and products. Key to adhering to the vast requirements set by local authorities, is to ensure that an acoustic solution is available before planning consent is given.
There are many factors that can affect the noise levels, so it is therefore advised that a customised solution to suit the individual building is found.