Solar heat gain coefficient and heat transmission coefficient of Al-doped ZnO thin-film coated low-emissivity glass

Abstract

In this study, we investigated the solar heat gain coefficient of aluminum-doped ZnO (AZO) low-emissivity (low-e) glass. Silver-based low-e glass has excellent solar heat shading performance. However, this is undesirable in winter. When the outside temperature is low, low-e glass should allow the passage solar heat into a building. Transparent conductive oxides can be applied for this purpose, as they transmit near-infrared light. Indium tin oxide (ITO) has already been used in this way. However, ITO is toxic, and the availability of indium is limited, making it expensive. As an alternative material, AZO is promising. We fabricated AZO films on glass substrates and measured their transmittance, specular reflectance and absorbance. The solar heat gain coefficient and the heat transmission coefficient were then calculated.