Fiber Optic and Tubular Lighting

By Nick Mosher

               Today our society is becoming more aware of just how important daylight is and its effects it has on people.  Tubular lighting has brought another way of allowing daylight to enter into an interior space.  It acts like an extended vertical skylight that carries light through a roof and even a floor and then diffuses it into a space.  The diffuser looks just like any ceiling light and can be made to look like a standard industrial light or a more elegant one.  Fiber optic lighting has recently developed and acts very similar to how tubular lighting does.  It collects direct sunlight and redirects it into a space where it then diffuses it.  Both are efficient and use natural free lighting compared to the use of artificial lights that require electricity consumption. 

                One tubular lighting unit is made out of a singular hollow tube with the internal lining covered in a highly reflective coating, usually aluminum, and like mentioned before a diffuser at the end where the light enters into a space.  At the beginning of the tube there is a half-sphere magnifying lens that collects the sunlight and redirects it into the tube. The tube sizes can vary from 8” up to 22” diameter and a 13” diameter tube provides the same amount of light as 7 100 watt light bulbs on a sunny day.  This system is very efficient in allowing a space with no windows to receive sunlight.  Up to 12 feet of straight tubing can provide 95% of the light that it captures from the outdoors.  Angles can be applied to the travel of the light but it will reduce the amount of light that reaches a room.  The light reduces also when the length of a tube system increases.  The system can reach lengths over 20’ but it is not as common².  Compared to the fiber optic system tubular lighting is cheaper and it has been around for a longer time which makes it the more common choice today.

                 Fiber optic lighting may be more expensive but it does have advantages over tubular systems.  Fiber optic systems can be very flexible and bend around corners as well as travel a longer length than tubular systems.  This is because the system is made out of not one large hollow tube, but several small glass or plastic solid tubes that carry the light. At the beginning of the tubes there is one Fresnel lens for each tube. The lenses can rotate in several directions and are programmed to follow the sun’s path to optimize on maximum light collection.  This allows more light to be directed into a room and the length of travel to be longer but it still does not allow 100% of light into a space.  At 33’ only 64% of light is provided and at 65’ only 40% of light reaches a space¹.  But those distances are much greater than tubular lighting.  Because the tubes are solid, there wouldn’t be a problem of critters entering into the tube and causing problems.  Overall for shorter distances up to 20 feet the tubular system is a better choice but for longer distances that need flexibility, the fiber optic system is the way to go. 

Notes:

1.            Alex Wilson. (May 11, 2010) Fiber Optics for Daylighting. GreenBuildingAdvisor.com http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/fiber-optics-daylighting

2.            Alex Wilson. (May 4, 2010) Tubular Skylights Introduce Daylight to Dark Homes. GreenBuildingAdvisor.com http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/fiber-optics-daylighting