Abstract: When appropriately coated, suspended polymeric films can substantially improve the energy efficiency of insulated glass units or IGUs. For example, when an induced-transmission low- emissivity film, such as PET coated with a dielectric/metal/dielectric or DMD stack, it suspended within an IGU, the thermal conductivity of the unit is reduced considerably. This is a consequence of both the attenuation of heat radiation from the low-emissivity surface and the reduction of convective heat transfer due to the additional partition created by the suspended film. If an IGU with more solar screening is desired, the low-=emissivity DMD coating can be tuned to decrease solar and visible transmission while maintaining relatively constant coloration. An alternative approach for increasing solar screening which affects visible optics less, is to replace the DMD coating with a Fabry Perot or DMDMD filter. As a final example of the utility of coated suspended films, an IGU with an exceptionally high energy rating can be obtained by combining an antireflected film with a pyrolytic low-emissivity glass. The antireflected film serves as a light weight `invisible' partition which decreases thermal conductivity with an insignificant attenuation of solar radiation. !8
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