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.