Greenery systems in historical urban centres: soundscape evaluation, design acoustic proposals

European cities are fast growing and noise pollution is becoming a major environmental problem. On the other hand, not many green areas remain in cities. The innovative proposal of this contribute consists in the use of green surfaces on buildings façades to abate traffic noise. Vegetation as sustainable element has gathered an increased attention for potential benefit in enhanced well-being of citizens and also for the resulting soundscape, with sounds and also aural visual interaction, useful for biodiversity. The main aim is the reduction of road traffic noise in the city centre of European cities, characterized by historical constrained buildings. Two real case studies, a square and an urban courtyard, respectively placed in Italy and in England, have been evaluated. For each case study, in situ measurements and acoustic numerical simulations have been performed. To run simulations it has been chosen the software CATT-Acoustic; then, as results check, simulations have been repeated by using CRR (Combined Ray-tracing and Radiosity) and Odeon. Acoustic properties of vegetation had been previously analyzed in laboratory. Effectiveness of various types of vegetation and their spatial distribution on the buildings facades to reduce traffic noise have been evaluated.