Analysis of Direct and Flanking Sound Transmission Between Rooms with Curtain Wall Facades

Curtain walls have nowadays reached good performance in terms of façade sound insulation, thermal insulation and solar protection. In this work, flanking and direct structural transmission are analysed with reference to the joints of the mullion of the curtain wall with lightweight plasterboard partitions. Airborne sound insulation and vibrational measurements were made in two adjacent rooms affected by the acoustic problems determined by the curtain wall joint. Traditional acoustic measurements carried out according to EN ISO 16283-1 highlight problems in sound insulation between rooms, but without any indication on different sound transmission paths through the wall. Vibrational measurements were made for every part of the system (frame columns and beams, windows’ glasses, plasterboard wall, plasterboard false ceiling, etc.) to better understand the sound transmission paths in these kinds of structures. Taking into account previous works and measurements made in this research field, different solutions for curtain wall structures are analysed and technical suggestions are given to improve airborne sound insulation between rooms separated by partitions mounted up to metal frames

A Psychoacoustic Investigation on the Effect of External Shading Devices on Building Facades

Due to energetic and natural lighting factors, building facades often present external shading devices, but the acoustic properties of such devices have not yet been well studied. This study was carried out using a full-scale model of a portion of a shading device, in a semi-anechoic chamber, using traditional and sound absorbing louvres. The psychoacoustic effects produced by the shading system were evaluated through comparisons between averaged values of loudness, roughness and sharpness levels, as well as sound pressure levels as reference. Results highlighted that the sound absorbing shading device offers good attenuation in terms of loudness, roughness and sound pressure level, with a small reduction in sharpness. The traditional shading system studied does not efficiently reduce the analysed parameters, or even worsens the situation. Several analyses of variance were carried out, one for each situation studied. The sound source position and the louvres’ tilt angle both produce statistically significant effects on almost all of the variations of the parameters studied. The analyses of the partial eta squared factors highlighted that source position and louvre tilt angle affect the variations of the parameters studied to a different degree in respect of the two types of louvres

The use of façade sun shading systems for the reduction of indoor and outdoor sound pressure levels

External shading devices are widely used in recent buildings because they reduce the greenhouse effect due to the solar irradiation through transparent surfaces and the glare effects in interiors. The acoustic effects of these devices have not been well investigated in the literature. In this article, we use a bi-dimensional pressure acoustics finite element model of a shading device attached to a building facade, in frequency domain, to analyse the effects both in the indoor and in the outdoor environments. The finite element model was validated with experimental measurements carried out in a semi-anechoic chamber and then extended to an urban scale to evaluate the effect in the reduction of outdoor noise due to traffic. To improve the acoustic effect of the shading device, a sound absorbing material was added to the bottom side of each louvre. Results of the simulations show that external shading devices tend to increase the sound pressure level over the building facade, while the introduction of the sound absorbing material behind each louvre reduces this problem. The dependencies of the sound pressure level reduction to the geometrical factors of the shading device were investigated by means of the finite element model. The installation of louvres on a building facade can affect also the sound pressure level over a facade of a building placed 20 m away, across a road. In this article, both the effect over the facade of the opposite building and the effect over the urban area between the two buildings are analysed

Experimental analysis of sound absorbing shading systems for the acoustic protection of façades

The problem of solar irradiation in building façades with large windows is often solved with the use of shading devices, such as brise-soleil systems, but their potential acoustic effects on buildings are usually neglected. The purpose of this work is a preliminary consideration of the acoustic behaviour of brise-soleil systems, and, furthermore, the evaluation of the possi- bility to improve their performances, in term of SPL abatement over the glass surfaces and overall enhancement of façade sound insulation. The paper reports the results of a study on two portions of the same office building, with shading devices installed in front of large windows. The system consists of lightweight metal louvers, manually adjustable in height and tilt angle. Both airborne sound insulation measurements (ISO 140-5:1998) and SPL measurements over the glass surfaces of the windows were carried out: results show that the louvers presence can produce an increase of the SPL over the glass surface as a consequence of the reflection of the sound. The bottom sides of each louver were modified, giving it sound absorbing properties, to try to improve the façade's sound insulation capability. Meas- urements were carried out with and without the absorbing material layer. Results show that the sound absorbing louvers improve the noise protection of the system, in terms of overall sound insulation and SPL reduction over the glass surfaces as well, cancelling out the nega- tive effect of the shading devices when installed without absorbing material

Le prestazioni acustiche di pareti: il confronto in Europa

The study, carried out between 2009 and 2013 as part of the European COST Action TU0901, concerning the Integration and Harmonization of Sound Insulation Aspects in Sustainable Urban Housing Constructions, led to the definition of a database of construction solutions and guidelines of good practice for sound insulation of buildings, at the European level. The outcomes of the research were the definition of harmonized indicators of acoustic performance of buildings, the elaboration of a draft of a European acoustic classification for dwellings, the definition of the correlation between acoustic performance of buildings and acoustic disturbance perceived by the population and finally the set-up of a compendium of constructive solutions in the various European countries for airborne and impact sound insulation in buildings. The article is organized in two parts, concerning the description of brick walls realized in different European countries (part 1) and the definition of the possibilities for improving the acoustic performances of brick walls mainly used in Italy (part 2). In the first part, the Italian scheme of acoustic classification of buildings is compared with the new proposal for acoustic classification elaborated by COST Action TU 0901, which is part of a new proposal for an International standard. The acoustic performances of typical brick walls realized in European countries are compared. Finally, some brick walls frequently realized in Italy, Spain and Belgium are analyzed in detail

Noise generated from large construction sites: Measurements and possible mitigations

In this study, the issue of noise arising from the activities of large construction sites is analysed. The problem is particularly significant when the sites are close to protected natural areas or to residential areas and also when the duration of the construction works is very large. The case of the construction of a mobile barrier system, known as the MoSE, for the safeguard of the city of Venice from intruding tidal waters, is here reported. Since the early beginning of the construction activities, in April 2005, noise emission monitoring was conducted in order to evaluate possible effects on the presence of bird communities in the surrounding areas and also to evaluate the noise disturbance in some of the residential buildings close to the sites. During the monitoring activity, it was possible to measure the noise levels, the noise spectra and spectrograms in real-time and occasionally even the audio signal for particular activities was recorded. The analysis of data collected in different periods defined the pile driving and some other activities as the most significant from the standpoint of noise emission, therefore the possibility to mitigate their emission was investigated