The Impact of Different Climates On Energy Efficiency of TiO2@W-VO2 Thermochromic Thin Film for the Application of Energy Efficient Smart Windows

Windows provide natural light and view of the outdoors in buildings that affect human health, satisfaction, and productivity. Nonetheless, poor thermal performance of windows is one of the most important factors which has limited architects to take the best advantages of windows in buildings. Employing enhanced glazing technologies such as smart and switchable glazing is an effective solution to this problem that can significantly decrease energy consumption in buildings while improving indoor environment quality. Various types of smart glazing have been proposed in this regard, among which thermochromic (TC) glazing due to its high energy saving and passive function with no activation electricity is considered as one of the most promising type of smart glazing. Thermochromic glazing through a reversible phenomenon changes its reflectance rate for solar infrared light in accordance to outdoor temperature. As the result, by reflecting solar heat radiation during summertime and transmitting that during wintertime, thermochromic glazing reduces energy consumption in buildings. Based on the thermochromic property of vanadium dioxide, the authors reported a type of TC coating by sol-gel method. After preparing the chemical solution and coating a fused silica substrate in the lab, XRD, SEM, photocatalytic, and spectrophotometry tests were carried out to characterize the fabricated TC glazing. In this research, we use a series of energy modeling studies to evaluate the performance of the fabricated TC glazing and quantify energy saving achieved by that in different climates and different geographical directions in an office room. The results suggest that the fabricated thermochromic glazing is more suitable to be applied in regions with hot climates. In addition, while in hot climates the TC glazing comes with higher efficiency on south facing windows, in cold climates, it performs slightly better on east and west windows.