Façade sound pressure level variations due to an external shading system: study with a calibrated finite element model

External shading devices can be used to reduce energy consumption and glare effects. Despite their large diffusion, acoustic effects of building shading devices have not yet been studied in details. This work presents a bi-dimensional finite element model developed to study the effects of dimensions, spacing and tilt angle of louvres in a simple shading system, compared with an identical one with sound absorbing louvres. The model was calibrated with experimental measurements carried out on a 1:1 scale model of a shading device, conducted in a semi-anechoic chamber. An extended microphone grid was used during measurements and sound pressure levels were averaged line by line to take into account differences between real 3D situation and virtual 2D domain. A good correspondence between measurements and the calibration model was found in the frequency range from 100 to 800 Hz, for both the traditional and the sound absorbing shading systems. Results of further simulations were expressed in terms of insertion losses, using as reference values the sound pressure levels simulated without the shading device.