COP v3.0:natural-light; light-transmission

11.5 Light Transmission 

The amount of roof lighting required in a building depends on the building design or use, the external light conditions of the location, and the reflectance of internal surfaces. Regular roof light areas range from 5% of the floor area for warehouses to 10 – 15% for industrial buildings, and 20% for sports halls and factories where intricate work is done.

Proprietary skylights are usually strategically positioned to bring borrowed light into specific areas that are not otherwise naturally lit. Often these are also designed to provide ventilation.