Ornamental illumination is any major permanently installed set of lighting fixtures on the facade which produce their own light and do not serve as an identifying logo. This does not include floodlighting; the light it produces must be visible at the source rather than reflecting off of the facade.

Common forms of ornamental illumination include neon strips, LED lighting, moving light displays, and glowing panels. Moving picture monitors (e.g. television screens or billboards) do not count as ornamental. Illuminated clocks and any types of functional lighting are also not counted, nor are patterns of regularly illuminated windows.

The fixtures themselves create the visible decorative light. Floodlighting instead illuminates the facade by reflection, while the functional displays and moving-picture screens excluded above have other defined purposes.