Reflective glass on window, door and fixed glass panel are chosen to complement the colour or design theme of a house or an office.
The glass, with it's reflective coat, is able to cut down the light and temperature from outside passing in.
Some people got mistaken that with reflective glass on the window, they do not need curtain for their room/house!
In daylight, the reflective glass appears to be a mirror from the outside because it is darker inside the house. At night, the role reverses ; when the light is switched on and without curtain, everything inside the house or room is very clear and sharp to the outside.