Light pipes 

·         Used for transporting or distributing natural or artificial light for the purpose of illumination,

·         Example of optical waveguides

·         Also called tubular daylighting devices, sun pipes, sun scopes, or daylight pipes.

·         divided into two broad categories

1.      hollow structures that contain the light with a reflective lining

2.      transparent solids that contain the light by total internal reflection.

• A tube or pipe for transport of light to another location, minimizing the loss of light;
• A transparent tube or pipe for distribution of light over its length, either for equidistribution along the entire length or for controlled light leakage.

·         A pipe that sticks out of a building's roof and reflects sunlight directly into an interior room.

Advantages

·         Provide natural light and of saving energy.

·         Transmitted light varies over the day and can be used with artificial light to have a constant illuminating level

·         Also used for underground structures which have no access to light.

·         More energy efficient than skylight since less energy escapes from the interior due to less surface area.

Disadvantages

·         less effective in cloudy weather as clouds obstruct incident sunlight from the rooftop collector

·         light pipes can still allow some heat transfer as well as condensation

·         increase the heating or cooling load for the space

Source: https://www.bca.gov.sg/zeb/daylightsystems.html