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 Sound Protection in the Lightweight Building Laws, Norms and Regulations Spatial acoustics also have to be taken into account in the case of high-demand buildings, exhibition halls and sports centres. Through planned absorption, they can lead to a reduction in noise level, for example in factories and offices. With the help of targeted reflection and absorption, they can also enhance the acoustics in theatres and auditoria. The following laws, norms and prescriptions only include the most important regulations
Important Excerpts from the UVV Lärm in brief: § 1 Area of Application This UVV applies to companies, provided that insured persons are employed subject to noise hazard. § 2 Establishing Terms Noise hazard in the sense of the UVV is the effect of noise on insured persons that can lead to the impairment of health, especially in the sense of a hearing impairment, or lead to an increased risk of an accident. § 15 Protection against Noise 1. The noise level in offices must be kept as low as the type of operations taking place there permit. Including noises from outside, the measurement level in offices at the workplace may not exceed:
Emission Limits in Accordance with § 15 of the Arbeitstättungsverordnung [workplace regulation]
Limits of the Ability to Withstand Noise The limits of the laws, standards and regulations previously cited are thoroughly justified, as damage to hearing as a consequence of noise cannot be reversed. For this reason, workplaces must be designed to exclude risks to health. In the case of severe damage to hearing, more than 50% of language can no longer be understood, as can be seen in Fig. 7.4.1. For this reason, employees in noisy areas above a location-related (person-related) evaluated level of 85 dB (A) must undergo prior and regular subsequent examinations. See UVV Arbeitsmedizinische Vorsorge [occupational medicine and health care precautions].
Fig. 7.4.1 Loss of Hearing in Decibels
The UVV Lärm [noise] states: The higher the noise level is, i.e. the louder it is, the quicker an evaluated level of 85 dB (A) is reached or exceeded, from which level a danger of hearing impairment arises. This means that a noise level of 115 dB (A) for 0.5 minutes will have the same damaging effect as an evaluated level of 85 dB (A) throughout a whole working day of 8 hours.
Planning Preparation Buildings must be given noise protection suitable to their function. According to the legal regulations, the industry, as well as the employer, is directly responsible for keeping damaging environmental influences, in this case the effect of noise, away from the neighbourhood, but also away from employees. At the moment, the building authorities do not yet set any conditions for noise protection. The factory inspectorates are responsible for the observation of the protection of health and safety standards at work and protection against emissions. The following conditions must usually be observed:
The reduction of the pressure caused by sound can take place in different ways. For this reason, the measures with which it will be possible to achieve an effective and reasonably priced reduction should be tested initially (see the graph below for this).
Note on Planning All the parameters of a building structure must be included in the technical sound considerations for an appropriate development of the components enclosing a space. Thus, the acoustic behaviour of walls and floor and windows, doors, gateways and penetrations must be taken into account. Machines set up, devices and stored goods must also be included. Firstly, it must be checked whether
Combinations of air and structure-borne noise and of absorption and insulation usually arise. In general, the reduction in airborne noise is the priority. The indices are:
Absorption of Airborne Sound The absorption of airborne sound can only be achieved through sound-deadening materials such as special soft foams or mineral wool (see Fig. 7.4.2). Insulation of Airborne Sound In contrast, mass is needed for sound insulation. The greater the mass and the higher the frequency, the better the measure of sound absorption, R w will be (see Fig. 7.4.3).
Fig. 7.4.2 Principle of the Absorption of Airborne Sound
Fig. 7.4.3 Principle of the Insulation of Airborne Sound
Products for Sound Absorption As has already been explained, the different parameters of a building structure must be included in the technical sound considerations to reduce the sound or the spreading of sound. The need for structural elements for sound absorption or sound insulation or both can arise from this. Different sandwich elements are available as required. G4 Acoustic Roof Element
Abb. 7.4.4 Dachelement G4-Akustik The G4 Acoustic Element consists of two steel covering shells with an insulating core of PUR hard foam and has two inserted soft foam strips made of melamine resin on its lower side. With this element, the absorption of sound at a frequency of 2000 hertz can be reduced by 60% in comparison to a normal sandwich element.
Fig. 7.4.5 Diagram of Sound Absorption Values for G4 Acoustic Elements in Comparison with Normal Sandwich Elements; Test Institute: Frauenhofer-Institut für Bauphysik, Stuttgart
HIPERTEC-Sound Wall and Ceiling Element
Fig. 7.4.6 HIPERTEC-Sound Wall and Ceiling Element The HIPERTEC-Sound is suitable both as a wall or a ceiling, everywhere where inner facings, separating walls or similar features with a high level of sound absorption and non-combustible insulation are required. The inner shell of the HIPERTEC-Sound element is perforated, with a proportion of holes of approx. 34%. The insulating core, made of mineral wool, building material Class A1, improves the sound absorption by approx. 91% (αs = 0.91) at a frequency of 2000 Hz. The fleece between the mineral wool and the perforated sheet prevents the escape of mineral fibre particles.
Fig. 7.4.7 Diagram of Sound Absorption Values for HIPERTEC-Sound Elements; Test Institute: Frauenhofer-Institut für Bauphysik, Stuttgart
Products for Sound Insulation In contrast to sound absorption, more mass is needed for sound insulation. The HIPERTEC roof and wall elements fulfil this requirement. These elements, with closed covering shells on both sides, have an insulating core of A1 mineral wool, weight by volume 100kg/m3. The high weight makes a significant contribution to improving the sound insulation values.
Fig. 7.4.8 HIPERTEC Roof Element
Fig. 7.4.8 HIPERTEC Wall Element
Sound Insulation Values The assessed sound insulation measure R w for the different thicknesses and versions of the HIPERTEC type roof and wall elements is:
Test Institute: Frauenhofer-Institut für Bauphysik, Stuttgart Often, too little attention to noise protection is paid during the planning and construction of buildings. Apart from this, planner and those putting the plans into action are frequently unsure about it. Both the contributions Grundlagen der Akustik [Basic acoustics] and Schallschutz im Leichtbau [Noise protection in lightweight buildings] are intended to make this complex subject easier to understand and to highlight a way in which parameters can already be considered in advance. Suitable sandwich elements are available for the different demands in lightweight buildings. Let us point out again that, in case of any doubt, an acoustic engineer should be brought in, because changes or improvements to the noise protection measures are not always possible later. Even if they were, they would represent longer deadlines and higher costs.
Author
List of Sources Laws / Regulations Bookshop or Carl Heymanns Verlag KG, Luxemburger Str. 449, 50939 Cologne, Germany Accident Avoidance Regulations Principles of Professional Associations for Occupational Medicine and Health Care Precautionary Examinations Noise Protection Worksheets DIN Standards VDI Guidelines EU Guidelines
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