Hybrid Solar Lighting Provides Energy Savings and Reduces Waste Heat
- ORNL
ABSTRACT Artificial lighting is the largest component of electricity use in commercial U.S. buildings. Hybrid solar lighting (HSL) provides an exciting new means of reducing energy consumption while also delivering significant ancillary benefits associated with natural lighting in buildings. As more than half of all federal facilities are in the Sunbelt region (defined as having an average direct solar radiation of greater than 4 kWh/m2/day) and as more than half of all square footage available in federal buildings is also in the Sunbelt, HSL is an excellent technology fit for federal facilities. The HSL technology uses a rooftop, 4-ft-wide dish and secondary mirror that track the sun throughout the day (Fig. 1). The collector system focuses the sunlight onto 127 optical fibers. The fibers serve as flexible light pipes and are connected to hybrid light fixtures that have special diffusion rods that spread out the light in all directions. One collector powers about eight hybrid light fixtures-which can illuminate about 1,000 square feet. The system tracks at 0.1 accuracy, required by the two-mirror geometry to keep the focused beam on the fiber bundle. When sunlight is plentiful, the optical fibers in the luminaires provide all or most of the light needed in an area. During times of little or no sunlight, a sensor controls the intensity of the artificial lamps to maintain a desired illumination level. Unlike conventional electric lamps, the natural light produces little to no waste heat and is cool to the touch. This is because the system's solar collector removes the infrared light-the part of the spectrum that generates a lot of the heat in conventional bulbs-from the sunlight.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 991661
- Resource Relation:
- Conference: World Energy Engineering Congress (WEEC) 2006, Washington, DC, USA, 20060913, 20060915
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ACCURACY
DAYLIGHTING
DIFFUSION
DIRECT SOLAR RADIATION
ELECTRICITY
ENERGY CONSUMPTION
FIBERS
GEOMETRY
GOVERNMENT BUILDINGS
ILLUMINANCE
LIGHT BULBS
LIGHT PIPES
MIRRORS
OPTICAL FIBERS
SOLAR COLLECTORS
SUN
WASTE HEAT
hybrid solar lighting FEMP energy savings