Taking into account acoustics of aeraulic networks is essential, especially for applications in the building sector, both for construction projects and for renovations.
In particular, inside the buildings, it is a question of ensuring:
- on the one hand: that the noise levels at the various delivery points of fresh air (air inlet) and also at the sucking points of stale air (air outlet) of Heating Ventilation Air conditioning (HVAC) installations i.e. the aeraulic networks ends, are compatible with the destination of the premises for which they provide air renewal
- on the other hand: that the noise transmitted by the casing of the ventilation network (i.e. by the ventilation ducts partitions) does not exceed some limit values in terms of noise with regard to spaces where they extend, which may be more or less sensitive at too high noise levels
Indeed, in many premises, the value of the normalized sound pressure level of the noise generated by building equipment:
- must not exceed some regulatory limits (in France) fixed by ministerial orders:
- in educational establishments e.g. in libraries, documentation and information centers, medical premises, infirmaries and rest rooms, music rooms: 33 dB (A) to 38 dB (A)
- in hotels e.g. in rooms 30 dB (A) to 35 dB (A)
- in health establishments e.g. examination and consultation rooms, medical offices and care offices, waiting rooms 35 dB (A); in treatment rooms: 40 dB (A); in operating rooms, obstetrics and work rooms: 40 dB (A)
- must not exceed some limits if the existing standardization is taken into account (in France):
- in offices and associated spaces: individual and collective offices, open spaces, meeting and training rooms, relaxation spaces, restaurants, circulation, naked stages: NR 30 to 50 dB (A)
- in the sports halls reserved for the practice of gymnastics, athletics, volleyball, handball, basketball, tennis, fencing, table tennis: 45 dB (A )
Of course, in many other rooms, noise reduction is desirable too, and outside buildings, one must also consider the acoustics of aeraulic networks and limit the noise for the same reasons and, in addition, so as not to disturb the neighborhood, respecting the emergence limit values: 3 to 6 dB (A); it is the difference between the A-weighted equivalent continuous pressure levels of ambient noise (installation in operation) and residual noise (in the absence of noise generated by the installation, but measured over its period of operation).
The acoustics of aeraulic networks is one of the main areas of intervention for ITS, with different activities:
- development of specific simulation software as part of R & D work (see Modules 1 to 8 of the SILDIS® software)
- simulation of the impact of aeraulic networks (as a whole, considering all the components) in terms of noise (the issue being acoustic comfort); drafting (using calculation software developed in-house or those of other publishers, including CFD, FEM, BEM) of calculation notes including for aerodynamics i.e. evaluation of the total pressure loss; acoustical engineering: measurements, study and advice
- dimensioning and marketing of soundproofing equipment (e.g. mufflers, canopies, other acoustic attenuation devices)
The acoustics of aeraulic networks as practiced by ITS also concerns industrial processes e.g. if they involve refrigeration or heating units, air intake or exhaust gas systems (e.g. for heat engines, combustion turbines), ventilation systems or other facilities with fans, axial or centrifugal.