Noise from facilities (e.g. industrial, artisanal, commercial, agricultural) is subject to regulation, particularly in the case of Establishments Classified for Environmental Protection (ECEP) subject to authorization put into service or modified after 1 July 1997 (in France, see the Order of 23 January 1997). This is why, in a preventive approach or if there is a complaint from the neighborhood: with regard to facilies noise, ITS offers an impact assessment and solutions to reduce sound annoyance.
Noisy facilities environmental impact
For installations, the prefectural authorization decree sets, for each period of the day (daytime and nighttime), noise levels (not exceeding 70 dB (A) for the daytime period and 60 dB (A) for the night period, unless the residual noise for the period considered is greater than this limit) not to exceed the establishment's property limits.
But in addition, the facility's compliance in terms of noise emissions is based on the consideration of emergence in Areas with Restrcicted Emergences (AREs).
Emergence is defined as (being) the difference between the A-weighted equivalent continuous pressure levels of the ambient noise (establishment in operation) and the residual noise (in the absence of the noise generated by the facility).
The zones with regulated emergence (ZER) consist on the one hand of the interior of buildings inhabited or occupied by thirds, existing on the date of the decree of authorization of the installation and their nearest possible external parts (courtyard, garden, terrace); on the other hand, building zones defined by planning documents enforceable against third parties and published on the date of the authorization order; and finally by the interior of inhabited or occupied buildings by third parties which were established after the date of the authorization order in the building zones defined above and their nearest possible external parts (courtyard, garden, terrace) , excluding those of buildings located in areas intended to receive craft or industrial activities.
Limitation of facility noise
For the daytime period, i.e. from 7 am to 10 pm, except Sundays and public holidays, the permissible emergence is 6 dB (A) when the ambient noise level is above 35 dB (A) but not greater than 45 dB ( AT) ; it is 5 dB (A) when the ambient noise level is above 45 dB (A).
For the night period i.e. from 10 pm - am and for Sundays and public holidays, the admissible emergence is 4 dB (A) when the ambient noise level is beyond 35 dB (A) but not greater than 45 dB (AT) ; it is 3 dB (A) when the ambient noise level is above 45 dB (A).
In addition, for noise from installations, the marked tone is detected in an unweighted third octave spectrum when the difference in level between the third octave band and the four nearest third octave bands (the two immediately lower bands and the two immediately higher bands) reaches or exceeds the following levels for the considered band: 10 dB from 50 Hz to 315 Hz, 5 dB from 400 Hz to 1250 Hz, 5 dB from 50 Hz to 315 Hz.
Noisy facilities environmental impact assessment
Depending on the context, the study of the environmental impact of noisy installations may include:
- on-site measurements of the sound pressure level e.g. near noise sources, on the property boundary, at the home of complainants. They are carried out (using regularly calibrated and verified sound level meters) by a human resource employed by ITS, experienced in physical measurements, specialized in instrumental techniques. These measurements are not only carried out to provide a (binary) answer to the question of the conformity of a facility, or to produce noise maps: they are sufficiently complete to allow use in the context of the search of solutions for noise reduction, which often motivates the recourse to ITS. In addition to the determination of the fundamental acoustic indicators which are the A-weighted equivalent continuous level, the emergence and the detection of marked tones, they may relate to the evaluation of the sound power level of noise sources, or the quantification of the sound decay by doubling the distance
- calculations of the sound propagation of the noise emitted by noisy equipment, for the evaluation (predictive or, for the purposes of comparison with the results of measurements in the case of modeling of facilities or sites) of the sound levels at specified locations e.g. property line, restricted emergence zones (REZ). This design office work is carried out at ITS by an acoustic engineer, with a degree in building physics, using specific simulation software
Noise studies in terms of environmental impact carried out by ITS relate to all types of facilties:
- those encountered in industry:
- outdoors e.g. including fans: air condensers, cooling towers, waste suction networks, extractions from paint booths or ventilation networks, or other noisy equipment e.g. grinders, crushers
- inside buildings, if their acoustic performance leaves something to be desired and does not sufficiently oppose the transmission of noise from machines (of all kinds) and production lines
Energy production occupies a very special place (due to the very high acoustic power of the noise sources involved, and their large size) not only for the noise radiated by the body of engines and turbomachines (compressors, combustion turbines) but also for the air intake, the exhaust (with chimneys) to which are associated very high noise emissions.
- those related to Heating Ventilation Air Conditioning (HVAC) of buildings and craft businesses:
- outdoors e.g. including fans: heat pumps, air conditioners, refrigeration units
- inside technical rooms, if their quality in terms of sound insulation is not sufficient and only imperfectly limits the propagation of noise from boilers, compressors, pumps, generators
Sound annoyance reduction solutions for noisy facilities
ITS can intervene not only to evaluate the compliance of a facility in terms of noise but also, where appropriate, to size and market soundproofing equipment to reduce noise annoyance.
In the case of facilities whose noise is (at least partly) related to the transport / discharge of fluids, ITS offers silencers (sometimes called "sound traps") e.g. for ventilation, exhaust, venting of pressurized gases and doublings of pipes and ducts. In other cases, the noise reduction means envisaged are often enclosures (sometimes referred to as "sound-reducing canopies") or acoustic screens (sometimes referred to as "noise barriers").
The development of sound annoyance reduction solutions for noisy facilities is often multi-disciplinary, since it must take into account the constraints linked to the operation and maintenance of the hardware and organs that compose them, and also calls upon know-how not only in terms of acoustics, but also in terms of aeraulics, fluid mechanics, thermics, construction technology; human resources have extensive experience in all these fields.
Any soundproofing equipment offered by ITS to limit the noise of installations is subject to a guarantee of acoustic performance.
Spread the word !