A year in green tech: Fiber-optic lighting

Prior to the invention of the lightbulb, we had only two options for lighting the indoors:  open flame or natural light.  Many older buildings today still carry the hallmark of design for natural lighting...high ceilings, light colored surfaces, and tall windows.  For centuries, our designs took into account the need people have for high quality natural light.  Over the past century, as we mastered the production of artificial light, our buildings adopted a different feel.  Ceilings got shorter, surface colors got more varied, and building shapes got chosen based upon maximum cost efficiency instead of ease of providing natural resources.  Although the last twenty years has seen a resurgence of the use of natural light in buildings, we still have a huge portfolio of buildings that do not have a way to provide higher quality, natural light to their occupants.  I should say, "We USED to not have a way...but we may have one on the horizon.

Working natural light into existing buildings poses challenges, but we have used two technologies - one old, one relatively new - to adapt.  Skylights provide natural light to many one-story office, education, and retail facilities.  Although they reduce the insulation value of the roof, they make up for that additional energy need by significantly reducing the need for lighting.  Walk into any new big-box retail outlet, and when you look up you will see a matrix of skylights providing most of the light to the store on a bright day.  For spaces where the configuration does not allow for an open view of the underside of the roof, a more recent technology called solar tubes allows designers to bring natural light into the occupied space.  Solar tubes look like a skylight at the roof level, but because the ceiling of the occupied space sits several feet below the roof, a tube with a white, reflective inside surface connects to the skylight and continues to the ceiling of the space.  At the ceiling, and special diffuser with a combination of reflective and translucent surfaces takes all the reflected light off the inside surface of the tube and sends it into the space as high-quality natural light.

What happens when neither of these will work?  What happens when the space sits multiple floors down from the roof, and running a tube through another floor makes no sense?

Fiber optic solar lighting works on a centuries old concept that we could use some media to transfer light from one place to another.  In the 1800s, inventors showed that light from a gas lamp could move throughout a house with the right types of pipes, and even Alexander Graham Bell thought of using light to transmit voice signals.  In the mid 20th century, research and advancement escalated and resulted in the development of fiber optic cables that could transfer large amounts of information using light signals, cables that carry the vast majority of our telephone and data communication today.  In addition, it allowed for advances in medicine that greatly improved the ability for surgeons to save lives.  Now, it can allow us to transfer light throughout even in buildings where daylight design did not occur.

The technology works on the basic principle that fiber optic cable carries light.  We use the medium to transfer information, but in its purest form, the cables transfer light.  A highly-reflective solar collector on the roof focuses light into the cable.  The cable runs from the roof to a specially designed fixture in the space that takes the focused light from the cable and diffuses it into the room similarly to a typical fixture.  The quality of light, however, exceeds that which we can produce from artificial light.

The technology still needs maturation to match the costs associated with artificial lighting, but as energy prices climb and people ask for higher and higher quality indoor spaces, fiber optic solar lighting has a real chance of becoming part of our everyday life.  This is especially true as we try to hold onto the embodied energy of a generation of buildings that we did not design for natural light.