Lightwell

In architecture, a lightwell,[NB 1] sky-well,[NB 2] or air shaft is an unroofed or roofed external space provided within the volume of a large building to allow light and air to reach what would otherwise be a dark or unventilated area.

Lightwells may be lined with glazed bricks to increase the reflection of sunlight within the space.

[1] Lightwells serve to reduce the necessity for electric lighting, add a central space within the building, and provide an internal open space for windows to give an illusion of having a view outside.

A subterranean lightwell by any frontage of a building for light to a basement is also called an area (or areaway in North American usage).

The lightwell was used in ancient civilizations, such as the Egyptians[2] and at the Palace of Knossos on Minoan Crete.