A review of complex window-glazing systems for building energy saving and daylight comfort: Glazing technologies and their building performance prediction

The increasing energy consumption and detrimental CO2 emissions contributing to global warming underscore the urgent necessity for energy conservation, especially within buildings. Among different building components, fenestration plays a pivotal role as it accounts for the majority of heat transfer across the building envelope. This emphasises the significance of window-glazing technologies in enhancing their thermal performance. Furthermore, window-glazing systems can lead to overheating issues, particularly in summer, and glare issues, especially in winter. These challenges have spurred the development of various advanced glazing systems. This paper provides a comprehensive review of these advanced glazing technologies based on their functionalities and working principles, with a focus on parameters such as U-value, solar heat gain coefficient and visible transmittance. Among these technologies, vacuum and aerogel glazing systems exhibit superior thermal insulation properties, with U-values below 1 W/m2 K, making them suitable for heating-dominated climates. Smart window systems, such as electrochromic windows, are ideal for cooling-dominated climates due to their low solar heat gain coefficient (0.09–0.47) and visible transmittance (0.02–0.62). Photovoltaic window systems not only provide effective thermal insulation and solar shading but also produce additional power for on-site use. Some of these glazing systems feature complex structures, which present challenges when integrating them into existing building simulation software to assess their impact on building performance. Therefore, this paper also examines techniques for conducting energy and daylight performance simulations for buildings that make use of complex window systems. Ultimately, the authors propose an approach to characterise the thermal, optical and electrical properties of a complex photovoltaic window system within existing building simulation software, such as EnergyPlus. This approach facilitates a thorough investigation into the effects of complex window systems on building energy efficiency and indoor comfort.