Introducing vegetation is an effective strategy for improving air quality and mitigating the heat island effect. Green modules, which consist of modules that support substrates and various plant species, integrate these elements. This study analyzes the acoustic absorption properties of a specific green wall module using an impedance gun and the Scan and Paint method for laboratory and on-site measurements. The impedance gun method is effective for in situ analysis, offering advantages over standardized techniques for inhomogeneous samples. The sound absorption coefficient of the substrate and the effects of different plant species were measured. Key findings reveal that the substrate primarily influences sound absorption, with its coefficient increasing with frequency, similar to porous materials. Vegetation enhances the acoustic absorption of the substrate, depending on coverage and thickness, with 80–90% of absorption attributed to the substrate and 4–20% to vegetation. However, not all dense plant species improve absorption; some configurations may decrease it. Improvement correlates with substrate coverage and vegetation layer thickness, while the impact of plant morphology remains unclear. These findings confirm vegetation’s potential as an acoustic absorption tool in urban settings. Additionally, green walls can enhance acoustic comfort in indoor environments such as offices and schools by reducing reverberation. They also improve air quality and provide aesthetic appeal, making them a multifunctional solution for modern architecture.

Systemic innovation must be the driving force behind actions to transform cities to address climate change. It includes transformations of environmental, social, economic, financial, technical, regulatory, and governance nature, supporting the permanent change of cities. Nature-Based Solutions (NBS), can be part of the tools to address the challenges ahead. This research aims to define a framework of action in cities for the implementation of NBS, demonstrating the importance of quantifying its benefits in environmental and socio-economic terms, to boost public policy design and investment in this field. This work is divided into two parts. The first part, analyses some of the European measures in the field of sustainable development in cities, focusing the research on the case of Madrid. And in the second part, some case studies are presented to reflect the measures and actions taken to promote the implementation of NBS in the city of Madrid. As a result, the potential levers of change for the implementation of NBS are identified, highlighting the importance of quantifying their effects to demonstrate the potential value that can be generated within cities.