In this sort of window, either the left or right frame serves as the axis of rotation: it moves to the left or right along a groove or rail attached to the top and bottom of the window frame. The other frame allows the window to open by rotating onto the exterior. The rotation and the horizontal movement occurs simultaneously.
Windows that open and close mainly through electric power using a switch or remote control to operate them are called power windows. As they can be opened and closed without touching them directly, they are used in situations where the window is question is rather heavy, or installed in locations where it is hard to reach. In recent years it has also become possible to operate such windows from a smartphone by linking them to internet technologies.
Installed in a high place such as the top of a stairwell, this sort of window facilitates “gravitational ventilation” by making use of how warm air rises. They are opened and closed using a switch or remote control, or using ball chains (operated manually). The ball chain mechanism is unique: the axis and chain that open and close the window are connected to each other, so that it opens when one pulls the chain from a distance.
Casement windows open by rotating horizontally to the left and right from the center, taking either the left or right edge as an axis. Some open into the interior, while others open onto the exterior. Both the left and right panels have the same dimensions: those that only open in one direction are called kannon-biraki (“goddess of mercy”), while those where one side is larger than the other are called oyako-biraki (“parent-and-child”). The ones opening in only one direction used in France since the 16th century are known as French windows.
A window that opens and closes by moving two or more parallel panels vertically over two or more grooves or rails is called a double sliding window, where both the top and bottom panels move. These sorts of windows developed primarily in the context of English stone built houses, and are commonly used even today in England as well as North America.
A window that opens and closes by moving two or more parallel panels horizontally over two or more grooves or rails is called a double sliding window, where both the left and right panels move. This sort of window is an ancient Japanese mechanism for opening and closing, and its original form can be traced back to the yarido sliding panels of the Heian era (B.C. 794 to 1185). They are commonly used even today in Japanese homes.