This is also true in tall buildings, however because the occupants in different parts of the building can be affected by significantly different noise levels depending on the distance between their occupied space and the road below, for example, it is not simply a case that a single sound insulation rating can be applied to the whole building.
Applying a uniform sound insulation performance rating to the entire building façade can also be unnecessarily expensive, particularly if that rating is based on those floors of a façade that are adjacent to a road. In tall towers there can also be a substantial difference in noise levels between the top & bottom floors.
To ensure that the façade is correctly specified to attenuate noise, we use a combination of on-site noise measurements and noise modelling software to accurately predict noise levels incident onto the development and façade of the building. We can even go so far as to predict noise levels within individual rooms.
Where external noise levels are high it is often necessary to use specialist acoustic laminated glass which is approximately double the cost of equivalent thickness non-laminated glass. Therefore it makes sense to tailor the façade specification depending on external noise levels and minimise the use of expensive laminated glass wherever possible.
The noise modelling image below illustrates the substantial difference in noise levels across the façade of a building and it demonstrates that the highest noise levels will be experienced closest to the main road and the lowest noise levels will be experienced in areas that are most shielded from the road network. For this particular building there is significant variance between the worst and least affected areas.
For the project illustrated in the image below we used a tailored approach and considered each room type within the building to ensure that higher sound attenuating glazing was applied for bedrooms and office spaces and a lower specification glazing was used for back-of-house spaces.
As is often the case the upper floors of this tower had sight-lines to the wider road traffic network and were, therefore, subjected to higher noise levels.
This concept can also be applied to buildings located next to a specific noise source such as a large night club; for a tall tower project in the UK one whole façade was upgraded with acoustic glazing due to the impact of a local night club and a more cost-effective less sound attenuating glazing solution was used for the rest of the building.
Our models also take account of the canyoning effect, whereby sound bounces between the facades of adjacent buildings, that is experienced when two tall buildings are located directly adjacent to each other with parallel façades. In these cases it is not unusual for a sidewalk conversation to be heard on the 15th floor or for noise from your own building’s roof top A/C plant to be bounced back at you.
By using our acoustic modelling software and carefully analysing each area of the building façade we give our clients the opportunity to move away from the use of one whole-sale acoustic solution for the entire façade and employ a tailored solution where standard glazing is used wherever possible and acoustic glazing is only used where absolutely necessary.
We can use our modelling software to enable clients to hear or ‘auralise’ the acoustics of a space long before the designs have been finalised and the building is constructed. This enables the fine tuning of a room’s sound characteristics and if we can influence the building layout and the materials used from the outset it can save time and money on expensive remedial treatments when the project is finished.
As part of a multi-disciplinary design team our 150 strong acoustics team across the globe work closely with our colleagues throughout the business to consider all acoustic aspects of tall building designs including building services noise and vibration, sound insulation between individual occupancies within the building, intelligibility of PA/VA systems and room acoustic comfort to meet the requirements of the end user.