Sound insulation improvements in lift-and-slide window systems

In recent years, significant attention has been directed towards enhancing indoor comfort in buildings, with acoustic comfort emerging as a key area of study. The sound insulation properties of building façades have a considerable influence on acoustic comfort, with glazing system often representing the most critical components. Meanwhile, the ever increasing demand for larger window surfaces to improve visual comfort, has led to a growing prevalence of thermal break lift-and-slide systems. The choice of window frame design for this window system is of paramount importance to achieve high sound insulation performance, as this depends on the closure system, the frame cross section, and the glass configuration in the frame. This paper aims to highlight critical issues of large sliding windows, exploring the acoustic performance of a lift-and-slide window through experimental assessments according to the ISO 10140 standard. The weighted sound reduction index (R_w) was assessed in laboratory; then, several modifications were implemented to improve the acoustic performance of lift-and-slide windows. Notably, the incorporation of sound-absorbing materials within the upper section of the frame yielded an R_w enhancement of 2 dB on average. Conversely, deficiencies such as improper glass orientation or improper frame closure systems led to R_w reductions of up to 4 dB. Finally, this study underlines the critical issues identified during the tests and provides practical recommendations to mitigate common installation errors.