The Need of Innovation for Solar Control Technologies

Giovanni Manfrè, Co/ MG Consult Srl

A deep investigation of solar control technologies to increase their market penetration has found technical and cost limits, in automotive and building fields. Their subdivision between IR absorption and/or reflection, seems not able to overcome the above limits to obtain the so called ¡°solar control efficient factor¡± (SCEF) TV/TE = 2 with TV ¡Ý 75% visible light transmission and TE whole sun integral energy transmission TE < 40%.

It is possible to show, theoretically and experimentally, that the highly requested SCEF by automotive and building architects, can be, at present, achieved only if the IR absorbing glazing (colored and/or nanoparticles embedded in PVB S-LEC by Sekisui) is suitably, complementary and simultaneously used in addition with at least one of the IR reflecting technologies (direct coating on glass; PET metallized film embedded in PVB South wall; PET metal free film (3 M)) to realize a unic solar control system.

As a consequence, the solar control glass becomes a complex system with the high cost and so quite difficult to get the market penetration for massive industrial products. Further, any of the above solutions are mainly suitable only with laminated glass, leaving the monolithic and the tempered glazing difficult to realize as a solar control.

Thus the author, since ten years, has investigated not classical routes and only recently his innovative investigation predicts that in the optical solar spectrum, in order to balance the whole incident light, a new fourth additional optical parameter is necessary to take into account: the light scattering involved together absorption, transmission and reflection especially by nanotechnology which starts predicting IR cut off even in their low and medium range 800-1.500 nm.

An alternative way to reduce the above limits is to realize a coating with by the multifunctional performances and in particularly suitable symbiosis between a solar control and heatable features. The author shows that this approach is so far not duly faced technically by the glass makers, at least for the automotive windscreen, leaving solutions as a compromise, difficult to satisfy the market demand.

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