ENABLING THIN-FILMS FOR SOLAR CONTROL TRANSPARENCIES - A REVIEW

The science of thin films has virtually become a field of study in itself in the second half of the 20th century. One outcome of this is the large-scale commercial application of transparent, inorganic films onto soda-lime-silica flat glass. The various reflecting and absorbing surface properties have modified our perception of what a window is. Thin films deposited onto glass by pyrolytic, electroless, vacuum, and chemical vapor deposition techniques have led to new aesthetic effects and some ability to manage solar energy for buildings and automobiles. The strategy has been to shade some of the visible, while maximizing attenuation of the solar infrared, and do both by reflection if possible. Improved attenuation of solar energy is calculated from spectral properties under standard conditions and expressed as a desirably low shading coefficient. A few important enabling thin film materials, ones exhibiting acceptable durability, have driven these developments. Some are discussed herein in context with present and future energy budgets. Possibilities for advancing the solar control strategy with switchable transparencies are also considered.