Acoustical Evaluations of a Double Skin Façade as a Noise Barrier of a Naturally-Ventilated Facade

Abstract

Urban traffic noise deters building occupants from utilizing window ventilation that helps lower the concentrations of indoor air pollutants. Traffic noise transmission via operable windows has become an environmental hazard, degrading the indoor acoustic quality of built environments. The objective of this study is to investigate the acoustical performance of shading louvers and air vents in a double skin facade (DSF) along with natural ventilation performance. A DSF mock-up was tested for noise reduction at the reverberation chamber depending on the percentage of air vent open surface area (e.g., 100% versus 40%), type of shading louvers (e.g., vertical versus horizontal), orientation of shading louvers (e.g., closed versus open position), and surface material of shading louvers (e.g., wood versus acoustic fabric-wrapped). In addition, a preliminary simulation study using computational fluid dynamics (CFD) software was performed to predict air velocity and air temperature distributions inside the DSF air cavity. The results showed that a DSF mock-up achieved noise reduction by approximately 33 to 36 dB(A). Vertical shading louvers tilted at a 90-degree angle, which is a closed position, was effective in noise reduction by 3 to 6 dB(A) at a lower mid- (500 Hz), a mid- (1000 Hz), a higher mid-frequency (2000 Hz and 4000 Hz) when compared to shading louvers tilted at a 0-degree angle (open position). However, the percentage of air vent open surface area, acoustic fabric of shading louvers, and type of shading louvers were not significant contributors to noise reduction. The outcomes of a preliminary CFD simulation study also showed that air vent configurations can improve the inflow of outdoor air volume with a comfort air velocity of 1.5 m/s.