Jalousie Window

A jalousie window ( /ˈdʒæləsiː/) or louvre window (UK) is a window which consists of parallel glass, acrylic, or wooden louvers set in a frame. The louvers are locked together onto a track, so that they may be tilted open and shut in unison, to control airflow through the window. They are usually controlled by a crank mechanism.

A patent for a louvered window was applied for in the US in 1900 and patented Nov. 26, 1901. Patent # 687705 by Joseph W. Walker, of Malden, Massachusetts.

Jalousie windows are best-suited for porches that are not climate-controlled and are located in mild-winter climates, and thus were very common on mid-20th-century homes in Florida, southern California, the deep South, and Latin America. They can remain open during heavy rains and (because the glass louvers protrude outward) keep most of the rain from entering in through the windows. It is impossible to achieve a good seal between panes. It is also very hard to secure this design, as the slats are easily and silently removed.

They were also widely used in mobile homes during the 1950s and 1960s before most mobile home manufacturers began switching to sliding and sash windows in the 1970s and 1980s.

They are also called louver/slated/glass crankout windows in certain legal circles; jalousie windows with extremely wide louvered panels (e.g. over six inches) are frequently called awning windows.