Hybrid lighting is a method of lighting that mixes the use of solar light with artificial light to illuminate buildings. Solar light is channeled in through fiber optic cable bundles and this light is supplemented with some type of artificial lighting. If it is sunny outside, a majority of the lighting in the building comes from sunlight. However if the Sun is blocked, photocells in the room detect the lower light levels and increase the amount of artificial light to compensate.
Hybrid lighting systems generally combine four different technologies into one effective system. Technologies used include devices to collect natural light, generate artificial light, transport light to where it is needed, and control amounts of natural and artificial light used.
How it Works
Hybrid lighting brings natural light into buildings from one or more mirror dishes installed on the roof. These dishes can swivel to follow the Sun through the sky. These dishes are around 1 meter in diameter and collect sunlight incident on the mirrors. The collected sunlight is then funneled down into the building through thick, clear fiber optic rods composed of plastic. These fiber optic rods are fairly thick and are made of plastic cores that transmit sunlight into the building and are wired similarly to electrical wiring. Before entering the room the light is fed through luminaries (bulb-shaped ends of the fibre opic wire) that diffuse the light softly, providing lighting for around 100 square meters of indoor space. In some cases, light tubes like the one shown in Figure 1 are used. These differ from fibre optic cables in that they are simply large plastic tubes that are coated in some reflective coating to bounce light down into the room.
Benefits and Drawbacks
The benefits of hybrid lighting are especially noticeable on a bright, sunny day. By bringing natural light into a space the need for artificial lighting is almost entirely removed. This offers considerable energy savings, which lowers energy costs. As well, these systems deliver visible light while blocking ultraviolet and infrared radiation. This means that hybrid lighting doesn't warm a building as much as using incandescent or fluorescent bulbs. As well, exposure to natural sunlight can reduce the symptoms of depression as sunlight has been shown to increase production of serotonin in the brain. As well, even though the upfront cost of installing a hybrid lighting system is more than installing traditional lighting, the system pays for itself over time in energy savings. With these systems, the annual cost to light a building can be reduced by up to 25%, thus making the payback time fairly quick. There's also fewer light bulbs to replace, since much of the light comes from daylight.
The main drawback of this type of lighting is that the cables that transport the light inside the building also absorb some of this light. This means that the cables can only carry light for a certain distance before it requires amplification. Because of this, hybrid lighting works only in rooms close to the roof level. This means that hybrid lighting has more application is stores, schools, and other public buildings where artificial lighting is used extensively in the daytime. In the home, where artificial light is used more in the evening, skylights or efficient light bulbs are likely a better option.
For Further Reading
- Wikimedia Commons. (August 13, 2015). Berlin Light Tube [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/c/c4/Berlin_light_tube.jpg
- Chris Woodford. (August 13, 2015). How does hybrid solar lighting work? [Online]. Available: http://www.explainthatstuff.com/hybrid-solar-lighting.html
- Michael R. Cates. (August 13, 2015). Hybrid Lighting: Illuminating Our Future [Online]. Available: http://web.ornl.gov/info/ornlreview/rev29_3/text/hybrid.htm
- WebMD Health News. (August 13, 2015). Unraveling the Sun's Role in Depression [Online]. Available: http://www.webmd.com/mental-health/news/20021205/unraveling-suns-role-in-depression
- Brighten Your Home. (August 17, 2015). Hybrid Solar Fiber Optic Lighting [Online]. Available: http://www.brightenyourhome.net/Hybrid-Solar-Lighting.html