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

Abstract

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 τlum = 0.58 and ΔτNIR = 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.