A Selective Window for Indoor Thermal Comfort in Building

Abstract

Buildings in Sudan experience significant amount of heat gain through windows and this affects the thermal comfort of buildings' occupants. There are many commercially available smart windows that control the reflection and transmission of visible light and infrared radiation, but they suffer from the high cost, low transmission of the visible light and some of them require external power for operation. The proposed glazing is relatively simple and it does not need any external source of energy to control its optical properties. Rigorous coupled-wave analysis (RCWA) has been used to design the glazing. The glazing consists of Induim Tin Oxide (ITO) and four periodic pairs of Si/SiO2, deposited on a glass sheet. The optimum thicknesses of Indium tin oxide ITO, Si and SiO2, obtained from the simulation, are ( 0.1 , 0.15 and o.4) μm respectively. The simulation has also shown that the filter transmits 70-80% of the visible light and reflects almost all the infrared radiation. The preparation of the filter and the testing has been performed at the laboratories of the Faculty of Science, University of Witwatersrand (Wits), South Africa. Magnetron sputtering technique has been used for the fabrication. Indium tin oxide (ITO), silicon (Si) and silicon dioxide (SiO2) have been used as sputtering targets. The magnetron sputtering system has been used to deposit a thin film from the sputtering targets onto the substrate. The fabricated filter has transmitted about 78% of the incident light and reflected almost all the infrared radiation. The experimental results have been almost typical to the simulation results.