Evaluation of Noise Mitigation by Different Materials and Balcony Configurations in Urban Street Canyon Facades: Casework in Aburrá Valley, Colombia

Abstract

The following work evaluates the acoustic performance of different sound-absorbing materials and balcony configurations used in the facades of urban street canyons in the Valle de Aburrá (AV) Colombia. The main insertion loss in the urban canyons was achieved by placing materials such as pumice stone and refractory brick on 16.7% and 8.3% of the facade surfaces. This obtained an environmental noise mitigation of up to 5.1 dB at a 5 kHz frequency and up to 3.6 dB at a frequency of 1.25 kHz. With other materials such as cork wood and metal wool, mitigations of up to 3.9 and 3.7 dB were achieved at the frequencies of 5 and 1.25 kHz, respectively. However, balconies caused an increase in ambient noise levels on pedestrian walkways with increases of up to 4.7 and 3.6 dB at a frequency of 1.6 kHz, regardless of whether materials such as pumice stone or cork wood were adhered to their surface. In recent decades, noise has become one of the most harmful pollutants for urban residents. Among the different sources of noise, car traffic has been identified as the main contributor. This can be aggravated by conditions commonly found on city streets, where tall, hard, close-spaced facades increase noise due to the different reflections that these conditions cause. This work shows the benefits that certain materials such as pumice stone, refractory brick, cork wood, and metal wool can provide in mitigating urban noise when placed in strips along the facade of a building. These materials stood out among others under conditions that might have resistance to weather. However, balconies projecting onto walkways could be counterproductive for pedestrians, since these features tend to increase the noise generated by cars circulating on the road. The potential application of this work is to mitigate noise pollution on urban street canyons.