Author: Yuen, Ka Chun
Title: Performance of ventilation-enabled noise barrier for residential development
Advisors: Tang, Shiu Keung (BEEE)
Kam, Ka Se (CEE)
Degree: Ph.D.
Year: 2022
Subject: Dwellings -- Soundproofing -- Design and construction
Buildings -- Environmental engineering
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Environment and Energy Engineering
Pages: xxii, 238 pages : color illustrations
Language: English
Abstract: In order to enhance the ventilation in the shadow zone of typical barrier design in residential development, new noise barrier design named "Ventilation­-enabled Noise Barrier" (VNB) is proposed. The design of a VNB similar to that of a plenum window: consisting of two rigid walls, with an inlet at top of source side and an outlet at bottom of receiver side, such that a passage with overlapping is created. By creating inner passage for air movement and sound transmission, the VNB modules achieve in balancing its acoustical performance and ventilation performance. This study focuses on the VNB acoustical performance. Laboratory measurement is used to assess the performance of the VNB modules, regarding the insertion loss of the measurement array behind the 1:4 barrier model. Cases of singular-modules of different overlapping, combinations of different singular-modules of same overlapping and different overlapping are put into test. The relative insertion loss of a VNB is the comparison between the insertion loss of VNB to that of a typical noise barrier design. Providing that the performance of the VNB modules is expected to be worse than the typical noise barrier design because of the additional opening, result shows that the performance of the VNB modules are generally better with increasing module overlapping. In the shadow zone of the barrier model, a large negative relative insertion loss zone created by the module outlets dominates the performance of the noise barrier model. In cases with twin- and dual- modules, a significant positive relative insertion loss zone is found, topped on the dominant negative relative insertion loss zone. By changing the overlapping length of the modules, the interference pattern behind the barrier model changes and thus affecting the location of insertion loss zones. The scaled-down modelling result is coherent with the computational simulation of the barrier model, which supported that in near field the increase of sound pressure level would not be greater than 1 dB(A). Numerical modelling by computational simulation is done to investigate the acoustic properties of the individual VNB modules and the combination of them. In low frequency range of 100 – 500Hz, peaks of radiated energy transmission from the outlets of the VNB modules are found. The number of peaks and the frequency which the peaks are located different for different VNB combination of various overlapping length. In the aim of a feasibility study of the VNB, further on-site validation of the VNB prototype has been carried out, where results matched the above-mentioned assessment results. The above collection of research proved that the VNB design has succeeded in taking good balance between its acoustical and ventilation performance, by sacrificing its acoustical performance in a small scale. The VNB can be a reference design in the barrier application of development with sensitive receivers in urban cities to provide better and sustainable living environment.
Rights: All rights reserved
Access: open access

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