The size and number of skylights are the most important decisions to make. Consideration also needs to be given to the position of light. For example, where the windows are facing east and there is good light in the morning, a room becomes dark in the afternoon.
For best results there should be one skylight in every 3 – 5 m of room length to distribute the light across the room. The total area of skylight should be 5 to 15% of the floor area of the room, depending on the number and size of the existing windows in that area.