This article presents an energy-saving window coating consisting of a shielding agent against both ultraviolet and infrared based on a nano-technology of conductive metal oxide. Coated windowpanes absorb the infrared rays from the sun and keep out the heat flowing into a room. A windowpane can be turned into a transparent parasol. The coating can be applicable from either outside or inside of windowpanes simply using a specially optimized spray gun. A uniform transparent film can be made on wide varieties of glass and film including wire glass, curved glass, large glass and resin. In cold winters, the heat-absorbing windowpanes reduce the outflow of heat from a room, and prevent condensation. Additionally, this film prevent bugs, such as moths, insects, bees, and brown marmorated stink bugs that have a habit of flying towards the UV light emitted by fluorescent lights, from approaching glass. Several works done for existing or newly constructed buildings are illustrated: a work done for a national museum has achieved 17.5% of reduction in electric consumption.