Impact of building façade design on road and rooftop noises using the discontinuous Galerkin finite element method

Noise pollution in cities impacts inhabitants' well-being and health, so reducing their noise exposure is a matter of public health. At the design stage, architects and engineers can exploit environmental acoustics simulation tools that can accurately predict the sound level resulting from a building façade design. This study numerically assesses the acoustic impact of different building façade design strategies for two sound source locations: one corresponding to road traffic noise and another to noise emitted by building services equipment, mounted on a rooftop. The outdoor sound propagation from a noise source in an urban setting is simulated in 3D using the nodal discontinuous Galerkin finite element method that captures wave phenomena at low frequencies more accurately than geometrical acoustics methods. This study finds that reflections from an opposite building in a narrow street canyon increase the sound level by up to 12 dB for a rooftop source. Also, it is found that balconies can have a screening or intensifying effect on the noise by −3.5 dB to 6.3 dB, depending on the location of the source. Furthermore, balconies can amplify the sound level at low frequencies due to resonances specific to the balcony dimensions. The balcony elements and the building façade redirect the sound. For balconies, the effect is minor, producing a maximum ±1 dB deviation, while the façade tilting has significant impacts regardless of the receivers for rooftop sources, −8.4 dB to 4.6 dB. The balcony elements and the building façade have mixed effects for road traffic sources. The numerical results were validated experimentally with a 1:10 scale model.