Multi-objective optimization of an anti-reflection AlN/VO2/AlN thermochromic window for building energy saving

The thermochromic smart window has shown potential for building energy saving by regulating optical characteristics according to real-time temperature. However, most existing studies on smart windows were conducted using an annual building energy-saving analysis. However, the ideal performance of a smart window that strikes a good balance between reducing energy consumption, eliminating the discomfort glare, and providing adequate daylight remains unclear. In this study, a novel AlN/VO2/AlN (AVA) multilayer thermochromic glass with improved transmission by using the thin-film interference principle is proposed, and the energy consumption and daylighting performance of the AVA windows are investigated using a multi-objective optimization method, considering different structural parameters in heating/cooling modes. The effect of different optical characteristics of the AVA glass on building energy consumption and the required annual daylight hours within the useful daylight illuminance (UDI300-2000) is analyzed to find out the Pareto frontier of the AVA windows. The Pareto Optimal Solution (POS) shows the best energy-saving AVA window should possess tau lum = 0.58 and Delta tau NIR = 0.33, which results in a maximum energy saving of 12.13 % for the office. This solution will strike a good balance between reducing energy consumption, eliminating the discomfort glare, and providing sufficient daylight.