Jalousie

Jalousie refers to a window or blind that uses adjustable horizontal slats, called louvers, to control light, air, and privacy. There are two main forms: jalousie windows, which use multiple glass louvers set in a frame and opened with a crank or lever; and jalousie blinds, which are interior or exterior coverings of horizontal slats that can be tilted to regulate visibility and ventilation.

Etymology and concept: The term jalousie comes from the French word meaning jealousy or privacy, reflecting the slats’ ability to provide privacy while permitting airflow. The concept is closely related to the broader category of louvered openings.

History and use: Jalousie windows and blinds were developed in the late 19th and early 20th centuries and became popular in warm and humid climates where ventilation was important. They were widely installed in tropical regions and throughout mid‑century architecture. Older designs often faced weather sealing and security challenges, and some models are prone to air or water leakage if not well maintained.

Construction and operation: Louvers may be made of glass, wood, aluminum, or vinyl, mounted in a frame that allows tilt adjustment. In windows, a mechanism such as a crank, lever, or rod tilts the entire array; in blinds, cords or a wand control the slats. When closed, slats can reduce rain intrusion, but sealing effectiveness varies by design and condition.

Advantages and drawbacks: Jalousie systems provide adjustable airflow and light control without fully opening the opening, and can offer privacy. Drawbacks include potential air and water leakage, maintenance requirements, and lower energy efficiency compared with modern sealed windows. Cleaning can be difficult, particularly for glass louvers.

Modern usage: While less common in new construction, jalousie designs persist in historic restorations and in regions that favor ventilation, and are still referred to as louvered or louvre windows in some markets.