Home Engineering Building Acoustics
Description of the Operation
The management has decided to have a new meeting room on a floor of an office building. The initial brief simply says: “We do not want to hear anything!” The location of the meeting room with regard to other spaces of the office floor is displayed in Figure 18.2.
Diagnosis and Feasibility
First, a meeting is held with the client’s officer responsible for construction work inside the building. One has to explain to the management that “not hearing anything” is a bit complicated and awfully expensive. After pointing out the standards’ recommendations, the acoustician gives a choice of privacy level (meaning a sound insulation of 45 dB at a minimum) or security level (meaning a sound insulation of 55 dB at a minimum). He also points out right from the start that removable partitions are out of the question due to their poor acoustic performance. Eventually, the client decides on a privacy level quality.
The acoustician defines a background noise level inside the meeting room (35 dB(A) from mechanical equipment) and a reverberation time (1.0 s in the 1000 Hz octave band).
Prior to the operation taking place, the acoustician checks through a diagnosis on the existing rooms whether the acoustic performances of the fagade and floors are compatible with those objectives (e.g., if the fagade or the floors are too weak, there will be such a flanking transmission that the sound insulation target will not be met). He will also look for such singularities as a thermal insulation along the fagade (in the affirmative, he will have to further check whether it is made of mineral wool or only of simple polystyrene) or a technical space along the fagade (that will have to be closed later on). More to the point, with the help from maintenance people or his colleague from HVAC, he checks that there is no ducting network transiting through the ceiling and floor voids.
Once this has been checked, a meeting is held between the acoustician and the end user. If some improvements are needed on the existing floors and walls, they are then identified. A last check is made to ensure that everything wanted, from the number of seats and tables to the video equipment and the eventual specific air handling unit, can be accommodated in compliance with the regulations (including safety requirements).
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