Environmental noise is a pervasive and significant issue in urban areas, negatively affecting the health and well-being of both residents and wildlife. Despite efforts under the European Noise Directive to reduce noise from sources such as road, rail, air traffic, and industrial activities, around 20% of the EU population still lives in areas where noise levels exceed health-based guidelines. The dense infrastructure and reflective surfaces in urban environments amplify noise levels, highlighting the urgent need for effective noise reduction strategies.

Vertical Greenery Systems (VGSs) can effectively reduce urban noise pollution when implemented thoughtfully. State-of-the-art VGS designs commonly incorporate multi-layer structures comprising a bearing wall, substrate layer, and foliage layer. This research aimed to optimize such VGSs in the early design stages to enhance their noise mitigation capabilities. Among the available generic models, the Transfer Matrix Method (TMM) offers the most comprehensive approach for modelling the acoustic characteristics of these structures. TMM allows for the modelling of acoustic properties on both sides of a one-dimensional fluid-like layer using effective, frequency-dependent parameters encapsulated within a 2 × 2 matrix. The total transfer matrix of the VGS results from the product of its individual layer transfer matrices.

It was established that to accurately evaluate the acoustic effectiveness of multi-layered VGSs, it is imperative to concentrate on the performance resulting from the superposition of layers under specific boundary conditions, rather than analysing individual layer parameters in isolation. This approach recognizes that there is no definitive answer regarding which specific components demonstrate superior performance. Instead, the intricate nature of superposition underscores the necessity for systematic experimentation with various component combinations and the manipulation of extrinsic variables, such as layer thicknesses, to optimize VGS performance.

In this research, the TMM was utilized to develop a tool for evaluating the acoustic performance of VGS designs, suitable for deployment during the early phase of the design process. The tool includes a comprehensive material library that allows stakeholders to explore various design options, making the approach more adaptable. It enables the evaluation of VGS design feasibility by examining the normal incidence weighted sound absorption coefficient and its corresponding absorption class. Additionally, the tool serves as a framework for conducting further analysis on the long-term environmental impact and economic viability of VGSs.