Development of a window system with optimised ventilation and noise-reduction performance: an approach using metamaterials.

Noise transmission is a key factor regarding indoor comfort and energy-smart Architecture and Engineering. In most cases, occupants of the building must choose between a naturally ventilated indoor environment or a quiet one. On the other hand, the acoustic metamaterials (AMMs) allow more customisable physical properties according to their spatial configurations, proving significant merits over traditional architecture and engineering materials. This PhD study will investigate AMMs techniques to develop a window system that can control the incoming noise while allowing natural ventilation. This is a crucial point for AMMs research. So far, even if many solutions have been developed to pursue this objective, they still lack ergonomics and human perception analysis. Through a multi-disciplinary methodology, the author first a) highlighted which are the ergonomic principles that add value to the window system from the users perspective, then b) investigated a series of suitable AMMs techniques to be applied for noise reduction and natural ventilation, c) developed a specific AMM design suitable to follow those ergonomic principles previously highlighted and assessed it through human perception, and finally d) optimised a full-scale prototype for a broad acoustic range and customisable ergonomic application. Social science, ergonomic, numerical, analytical and experimental studies were used throughout the PhD project to draw a full-scale window prototype using AMMs to allow natural ventilation independently from the outdoor noise situation. The so-called acoustic metawindow (AMW) allows Transmission Loss (TL) of 10-80dB on a significant frequency range for human hearing (50-5000Hz) in an open configuration while allowing sufficient natural ventilation. In addition, the AMW is proved to positively impact the indoor environment from both physical and human perception points of view thanks to its ergonomic nature. This project will open a new AMMs field of investigation that is not limited to noise reduction but also includes outdoor stimuli optimisation towards a more comprehensive indoor comfort.