A Guide To Acoustics In Buildings For Specifying Movable Wall Systems.

ACOUSTICS IN BUILDINGS

A GUIDE TO THE SPECIFICATION OF MOVABLE WALLS

When considering what type of movable partition to use within a building it is important to bear in mind all aspects of the specification, particularly in relation to:

• The expected level of on-site performance regardless of how individual rooms/areas are to be used.
• The ease of operation of the movable wall.
• The ability to store the panels when the rooms are opened up.

Although the above are important in relation to general use, many other factors can have a significant impact on the overall performance of a product. It is of critical therefore that these factors are given full consideration before a specification is issued so that the installation provides the levels of acoustic performance that is acceptable in operation.

Before considering the complexities of controlling sound in buildings it is important to have an understanding of the basic principles and terminology of acoustics and how performance values are arrived at.

What is Sound?

Sound is a form of energy created when air is disturbed in some way causing changes in air pressure that radiate from the source
of the sound in waves. Sound can be airborne; typically that of a human voice or impact: for instance the sound of heavy footsteps on a floor.

Sound waves vibrate at different rates or frequencies as they move through the air and are measured in cycles per second or Hertz; the faster a sound wave passes a given point, the shorter the wavelength and in turn the higher the frequency.

Vibrations in the air caused by the sound determine how loud it is; the stronger the vibrations the greater the ’amplitude’. The length or duration of a sound i.e. it’s reverberation time or echo, is determined by the extent to which the energy is expended on contact with surfaces within a room.

The Role of the Partition Wall

In commercial buildings the layout of an office is required to create areas that provide varying degrees of function and privacy. In relation to sound insulation, a partition is expected to deal with airborne sound and prevent or reduce noise travelling from one room to another. The type of activity to be carried out and the level of mutual noise disturbance that can be tolerated determines the appropriate standard of privacy between rooms.

Where a partition is made up of different elements i.e. including doors and glazing, with different sound reduction characteristics the overall level of reduction will be lower than that of the highest rated part regardless of the relative size of lower rated product.

Acoustics & Building Regulations

Part E of the Building Regulations was updated in 2003 to include details of minimum levels of acceptable sound performance in certain types of buildings, particularly schools (Building Bulletin 93 [BB93] provides more detailed guidance for acoustic planning and design in schools). However there is little mention of In commercial buildings legislation covers maximum noise levels from a health and safety perspective but there is no regulation for minimum levels of sound reduction; however the use of specific areas such as conference/meeting rooms etc. makes the need for good levels of sound insulation in practice no less important.

Below is a list of the recommended maximum noise levels acceptable in various environments: –

Specifying Movable Walls

Movable walls are an increasingly important part of building design, allowing architects and designers the freedom to fully utilise space within buildings while providing end users with flexibility of usage. Focus on acoustic control and product performance is essential in the development of specifications that deliver buildings that are fit for purpose. The desired flexibility can only be achieved in practice if the Movable Wall product chosen reconciles the expectations users have with the space concerned.

High Performance Movable Walls

In buildings where a very high degree of sound insulation is required, there may be a need for ratings in excess of 50dB(DnTw). Due to the influence of site conditions and flanking structures, this is unlikely to be provided by a single movable wall. In such cases two movable walls would need to be installed independently with the tracks separated by about 300mm. The existence of gaps, even a few millimetres, has an increasingly dramatic effect on overall sound insulation as the dB(Rw) rating of the product rises.

Where high performance walls are installed regular maintenance is essential to ensure that all seals continue operating to the highest standards.

For further information on moveable wall installations please see here.

Please view and download our brochure A Guide To Acoustics In Buildings .

A Guide To Acoustics In Buildings For Specifying Movable Wall Systems