Paper Conference

Proceedings of BSA Conference 2015: Second Conference of IBPSA-Italy


Prediction of the Sound Insulation of Double Leaf Facades with Openings for Natural Ventilation

Egzon Bajraktari, Josef Lechleitner, Ardeshir Mahdavi

Abstract: This paper explores the reliability of acoustical simulation for the prediction of the sound insulation of double leaf facades with openings for natural ventilation. The subject of the study is an experimental modular double-leaf wall with multiple opening possibilities. Different elements can be opened in both (i.e., internal and external) layers, so that multiple opening configurations can be studied both empirically and computationally. The actual acoustical performance of the wall was captured through parametric laboratory measurements. The respective configurations were then modelled using a state-of-the-art room acoustics simulation program. Thereby, alternative representations of the double leaf facade were considered. In one representation, the facade layers were explicitly modelled in terms of two separate entities with the facade cavity as an interstitial space. In other representations, the sound transmission through the wall and the acoustical coupling between openings on the two layers were modelled as separate processes. The initial acoustical model was calibrated by comparing the measured and the simulated reverberation times in the laboratory's two chambers. Specifically, the calibration involved the adjustment of the absorption properties of surfaces of the laboratory chambers so that an improved match between the measured and simulated reverberation times could be achieved. Computer simulation and laboratory measurement results pertaining to the sound insulation of the experimental wall were compared for multiple opening configurations. The results illustrate the potential as well as the considerable limitations of acoustical performance simulation toward prediction of the sound insulation of double-leaf wall systems. Likely reasons for this circumstance as well as potential improvements are discussed.
Pages: 59 - 65