Polymer-Dispersed Liquid Crystal (PDLC) smart switchable windows for less-energy hungry buildings and visual comfort in hot desert climate

Smart switchable glazing windows have become an alternative energy-saving solution for achieving visual comfort and reducing energy consumption. In Saudi Arabia, significant amounts of energy are lost through external envelope facades due to the integration of conventional glazing systems. Thus, in this work, experimental characterisation and numerical analysis were carried out on a scale model integrated with a Polymer-Dispersed Liquid Crystal (PDLC) smart window in a hot desert climate. In the first part of this paper, an outdoor scale model was used to evaluate the thermos-optical properties of a PDLC smart window. The experiments were conducted in the spring season in actual conditions, while the state of the window (transparent and opaque) was adjusted. The data were validated and employed to develop a numerical model for energy consumption and visual comfort analysis. A comprehensive parametric analysis of the window-to-wall ratio (WWR) in cardinal orientation was carried out using the EnergyPlus9.4 and Climate Studio packages. The results indicated that the PDLC glazing in the system was able to achieve the Leadership in Energy and Environmental Design (LEED) LEED4.1 standard partially due to the increased Annual Sunlight Exposure ASE(> 1000lx 250h), even with low transmittance and WWR in both states. The binary behaviour of the PDLC glazing was able to reduce the emission of CO2 from 32.5-89 kg CO2/m(2) using the WWR fully for the transparent and opaque states, respectively. Overall, this study contributed to the knowledge on the integration of smart glazing in buildings with low energy consumption and indoor daylighting in a hot desert climate.