Low emissivity and EMI shielding window films

A method for selectively reducing emissivity through a surface, the method comprising:

• providing a low emissivity composite film, comprising:
• a film substrate;
• an underlayer of abrasion resistant hardcoat material coated on the film substrate and comprising a crosslinked acrylate polymer and metal oxide nanoparticles, the underlayer having a dried thickness of about 2 to about 6 microns and an abrasion delta haze of about 3 to about 5%;
• and
• at least one infrared reflective layer;
• a transparent protective top coat comprising a polysilazane, fluoro silane, fluoroalkyl silane, or combination thereof, wherein the protective top coat has a thickness of less than about 0.5 microns and is disposed over the infrared reflective layer;
• wherein the composite film has an emissivity of less than about 0.30;
• and
• wherein the underlayer is disposed between the film substrate and the infrared reflective layer;
• and
• selectively positioning the low emissivity composite film relative to a generally planar surface so that either;
• the low emissivity composite film is arranged in a first position generally coplanar with the surface to reduce emissivity through the surface;
• or
• the low emissivity composite film is arranged in a second position generally non-coplanar with the surface to not reduce emissivity through the surface.