A review of the application of green walls in the acoustic field

Abstract

Green wall technology, including green façades and living walls, presents a promising solution to encounter the negative impacts of noise pollution. Research and development of green walls are steadily progressing in multiple fields, including but not limited to the environmental, social, and economic areas. Compared to other themes, the number of acoustic studies of green walls is relatively low and lacks relevant review papers. The purpose of this paper is to give a systematic review of the application of green walls in the acoustic field and clarify the key factors that influence the acoustic performance of green walls and the main obstacles that obstruct the broader application of green walls. A total number of 34 papers published in the past 10 years are reviewed. This study identifies that the acoustic applications of green walls are mainly in four aspects, namely laboratory applications, outdoor applications, indoor applications, and audio-visual applications. Vegetation morphology and properties of substrates are the two crucial factors determining green facades and living walls’ acoustic properties, respectively. High installation, operation, and maintenance costs and plant-induced problems are recognized as the main obstructions. A few possible topics are recommended for future study as well.

Applying vertical greening systems to reduce traffic noise in outdoor environments: Overview of key design parameters and research methods

“…Studies addressing the acoustics of green walls about outdoor applications will therefore be reviewed in this paper. Different from two other review studies by Yan et al 25 and Oquendo-Di Cosola et al, 26 this article puts the emphasis on the application of underlying acoustic principles and research methods by design and engineering scholars and practitioners.…”

Vertical Greening Systems: A Perspective on Existing Technologies and New Design Recommendation

“…Both types of green walls provide similar benefits in terms of building thermal performance and energy savings [32], but are not as effective in reducing noise penetration and reverberation compared to other systems due to the lack of plant-growing medium which acts as an insulating barrier for the building façade [33]. Irrigation at height for these green walls is typically not required, and manual irrigation is sufficient; however, if automated watering is required, irrigation systems such as drip, sprinkler, or wicking can be installed within the planter box.…”

Vertical Greening Systems: Technological Benefits, Progresses and Prospects

“…In addition, a green wall is an alternative form of constructed textiles, which has been well recognized and widely applied worldwide for various wastewater treatments, particularly in green water treatment [16,35]. In terms of social health, it provides aesthetic and therapeutic benefits, improves the city image [21,36,37], reduces noise [38,39], improves the lifestyle of residents, increases architectural value [40] and complements thermal [41] and acoustic protection [42,43]. Economically, cooling can save energy, reduce energy consumption [25,44,45] and prolong the service life of the roof membrane [35,46,47].…”