Prasanta Kumar Biswas
Solar radiation (~0.2–2.5 µm) on earth surface involves illumination and heat generation as it covers the electromagnetic waves of visible and near-IR region. The Air Mass (AM) spectrum of solar radiation shows irradiance decreases with the increase in tilted angle. Hence, designing of window glass system should be made in such a manner that solar radiation should enter the room at high angle of incidence highlighting reasonable illumination (100–300 lux) and suitable thermal comfort. To remove the unwanted heat absorption by glass, a suitable layer of low thermal emissivity with heat reflection property should be deposited onto the window glass. On the basis of this idea a low-e material, Indium Antimony Oxide (IAO) (In: Sb=97:07), a wide band gap semiconductor (band gap, ~3.5 eV) has been chosen and deposited on to window glass of dimensions, 500mm x 500 mm by soft chemistry method. The developed film is transparent in the visible and electrically conducting with>25% reflection in the Mid-IR region. The performance of the film as window glass fenestration in day time is characterized by evaluating direct solar optical properties from the spectral data measured at different angles of incidence by UV–VIS–NIR
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