In order to provide natural light where there are no opportunities to install roof or vertical windows, an effective solution can be a Light Tunnel

Thanks to the light tunnel, natural light gets into the building illuminating its interior. In the other rooms light tunnel can be an additional source of light.

The amount of light which enters the room via the light tunnels depends on the light intensity outside the building. The more light that illuminates the dome of the light tunnel, the more light is conveyed to the building interior. The below diagram illustrates the full amount of the daylight (lm) depending on the month and cloudiness measured at the light tunnel dome.