Low-e glass or low-emission glass.
Glass used for production of IZO glass which is very efficient when talking about preserving heat in a room, lets light through and solar energy too into interior and prevents heat outflow. Low-e glass is transparent flot glass coated with metal oxydes by by the method of cathode vapour disposition in vacuum conditions. This vapoured layer blocks long-wave heat radiation and is known as low-emission layer.
It increases energy savings up to 70% when compared with standard IZO glass. (picture of LOW-E).