number of skylights

The number of skylights is the total quantity of distinct openings in the horizontal or slanted roof of a structure or module which are filled with glass (possibly along with framing elements) and allow light into the structure.

Skylights are counted in a manner similar to window apertures, and thus may include multiple individual panes of glass or multiple framing units, as long as they are not separated by structural beams, walls, or sections of opaque roofing. A single skylight may thus be a single small pane of glass or a giant atrium-spanning glass roof.

Windows installed in a roof, such as dormer windows, are not considered skylights.