Assessing the Performance of a Thermoresponsive Liquid‐Based Smart Windows for Building Thermal Regulation through Outdoor Experimentation and Computational Modeling

Abstract Smart windows have the potential to respond dynamically and passively to external stimuli, controlling the amount of light passing through the window. When a smart window switches from a clear to a translucent state, energy flow through the window is partially attenuated, allowing a room to cool down passively, thereby reducing the energy and fossil fuel consumption for air conditioning. The smart window demonstrated here consists of a thermoresponsive liquid consisting of Tergitol 15‐S‐7, which can dynamically and passively switch the window's transmittance when a temperature of 39 °C is reached. It is also demonstrated how the transition temperature can be lowered by adding salts. Outdoor experiments in realistic environments show that the temperature of a model house built with a thermo‐responsive window can achieve an indoor temperature of 7 °C less than a control house with an ordinary window. This study quantifies the energy savings possible using such windows at the building scale for cooling and heating in different climates and times of the year.