The term reflective glass does not refer to mirrors only, though such glass can provide mirror-like qualities. Reflective glass has a metallic coating to help reflect heat, which in turn lowers energy costs for the building, as it takes less energy to regulate the building’s interior temperature. Reflective glass can give the appearance of a one-way mirror, providing added privacy for building occupants. It is most frequently used for building facades.
The metal coating on reflective glass can be added to the hot glass during the float process. This kind of coating is called a hard coat and reflective glass with a hard coat can be cut, heat strengthened or toughened (tempered). The other way of adding a metal coating to glass is by adding it via a vacuum after the glass has been finished. This is called a soft coat. A soft coat is more susceptible to scratches and other damage, so is usually applied to the inside surface of a glass pane as part of a double-glazed system.