Traffic noise level predictions for buildings with windows opened for natural ventilation in urban environments

The aims of this research are to discuss acoustical building performance for natural ventilation systems and to predict traffic noise level for inhabitants residing in urban settlements. Natural ventilation systems use outdoor air to improve the quality of indoor environments and can reduce energy consumption. However, natural ventilation systems create an acoustical problem. For example, if windows are opened for natural ventilation, outdoor traffic noise can disrupt people working and sleeping in the building. In this study, a new method that combines an algorithm to predict traffic noise levels (calculation of road traffic noise) with the Federal Highway Administration Traffic Noise Model's vehicle noise spectra correctly predicts the properties of noise propagation and attenuation through openings in urban environments, as well as outdoor sound propagation, sound reduction index, and indoor sound transmission. In order to develop this method, various traffic noise prediction methods to calculate sound attenuation during propagation outdoors based on International Organization for Standardization 9613 were analyzed. This study also describes the noise attenuation effect from surrounding elements, such as building envelope, location of openings, opening ratio, and indoor boundary conditions. The results of the simulations indicate that the integrated noise evaluation method can successfully predict the acoustic performance of natural ventilation systems in urban areas.