Highly concentrated optical fiber-based daylighting systems for multi-floor office buildings

• Daylighting systems using a parabolic trough and linear Fresnel lens.
• Uniform illumination into the optical fibers and to large-scale building interiors.
• Hybrid system combining daylight and LED light improves illumination quality.

Daylighting is essential for improving indoor environments and reducing electric lighting power consumption in office buildings. Traditional, fiber-based daylighting systems were implemented only on a small scale. To this end, two efficient approaches are presented. The first approach consists of a parabolic trough and the second approach contains a linear Fresnel lens. Sunlight is captured through the concentrator and distributed through the optical fibers. Since it is difficult to achieve a high concentration, a trough compound parabolic concentrator (CPC) is used to pass the maximum captured collimated sunlight into the optical fibers in both approaches. Optical-simulation results have shown that the efficiency achieved in the implemented daylighting systems—which is estimated based on the average illuminance in the interior and on the illumination quality of the system through combining daylight and light-emitting diode (LED) light—is better than that of traditional lighting systems.

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