Balancing ventilation and sound insulation in windows by means of metamaterials: A review of the state of the art

In buildings, natural ventilation plays a major role in ensuring satisfactory indoor air quality levels, but increased noise levels due to urban noise may become an unwanted side effect. Hence, optimizing at the same time both noise reduction and ventilation represents a challenge in the sustainable design of innovative windows. A comprehensive understanding of the current state of the art, the design criteria most frequently used, and the correlations existing between the acoustic and ventilation performances is an essential step towards the development of window solutions for an efficient building envelope. Among the possible solutions, metamaterials offer new opportunities and customized solutions to solve this issue. This review aims to provide an accessible and updated overview of the criteria to adopt when developing efficient windows, focusing on metamaterial applications for designing innovative components able to promote effective ventilation simultaneously with sound attenuation. A total of 56 studies were reviewed to identify current research trends to address sound insulation and ventilation in windows using conventional approaches and metamaterials. The main streams of current research, the knowledge gaps, and the areas still to be explored are finally highlighted. • A review of studies on ventilation and acoustic properties of windows is carried out. • Sound insulated open windows may contribute to increase sustainability and IAQ. • Conventional and Innovative solutions based on acoustic metamaterials are studied. • Review shows promising results although often limited in frequency band extension. • Difficulties in characterizing proposed solutions in consistent ways are outlined.