Advancing fiber-optic daylighting system integrated with freeform optics for indoor workstation lighting

A fiber optic daylighting system is an evolving technology for transporting illumination from sunlight into building interiors. This system is a solution developed by daylighting designers to reduce operational costs and enhance comfort. As an innovative technology, fiber optic daylighting systems can illuminate building interiors efficiently compared with other daylighting strategies. However, as a transmission medium in daylighting systems, optical fibers require uniform light distribution in sunlight concentration, which could generate heat. Therefore, this study aims to investigate the effect of heat buildup produced by end-emitting fiber optic daylighting systems in tropical buildings. The applied method adopts a new fiber optic daylighting system technology from Sweden called Parans SP3, with a 10 m cable to be tested in an actual room size under the Malaysian climatic environment, particularly within the vicinity of the main campus of the Universiti Sains Malaysia. Results show that the system generated a temperature of 1.3 °C under average conditions through fiber optic diffusers and increases indoor temperature by 0.8 °C in a 60 m3 room. According to the results, applying fiber optic daylighting systems, as renewable energy sources, generates extra heat gain in building interiors in the tropics.

Designing an integrated daylighting system for deep-plan spaces in Malaysian low-rise buildings

Review on fibre-optic-based daylight enhancement systems in buildings

Design of a Hybrid Fiber Optic Daylighting and PV Solar Lighting System

This paper discusses a Fiber-Optic Hybrid Day-Lighting system that can cut energy consumed by buildings for lighting significantly. This system is designed for mobile applications such as military shelters. The system is comprised of two primary components: the solar collector and the Solar Hybrid Lighting Fixture. The first component, the solar collector, consists of a housing, structural stand, a dual axis tracking system, Fresnel Lenses, secondary optics, and fiber-optic cables. The collector is integrated into a dual-axis tracker, which is then mounted on a tripod. The tripod can be staked into the ground and weighed down to protect the system from any wind loading and the collector height can be adjusted so that there is no shading of the collector by nearby structures. The collector with an aluminum housing holds eight 10-inch diameter Fresnel Lenses that focus sunlight onto eight secondary optics based on TIR (total internal reflection) which filter UV/IR and deliver uniform light to the fiber-optic cables. The secondary optic is coupled to the fiber-optic cable with index matching gel so that Fresnel reflection losses are minimized. The solar collector tracks the sun’s movement through the day with a dual-axis tracker (azimuth/tilt), ensuring the light is concentrated into the fiber-optic cables. The optics has been designed to have a high half-acceptance of 1.75° and can accommodate a tracking accuracy of 1.50° or better. The opposite end of the fiber-optic cable attaches to the second part of the Day-Lighting system, the Solar Hybrid Light Fixture (SHLF). The SHLF comprises of two lighting systems: 1) a solar fiber-optic system and 2) an LED system. The fiber-optic cable is coupled to an acrylic light diffusing rod that evenly delivers the light into the room. During sunny periods, depending on the length of the cable, solar fiber-optic lighting could provide full illumination of the space. In order to keep lighting uniform even during fluctuations of the light output from the sun during cloudy periods, the LED portion of the light will allow for constant lighting at a lower power consumption. The LED lighting has dimming capabilities due to a photosensor that regulates the light output of the LEDs based on how much solar light is delivered by the fiber-optic cables. On a typical sunny day with an overall concentration factor of ∼400 from the Fresnel Lens system to the optical fiber, it is possible to generate an output of 2,000 lumens with a 20-foot cable, with each fiber-optic cable experiencing a 1% loss of light per foot of cable. The LED portion of the hybrid light fixture produces about 1,800 lumens as well.

Daylighting gets more attention as people seek better quality of light meanwhile saving electricity which in buildings. Fiberoptic based daylighting systems give us the freedom to provide natural light to any space in the building including north-facing rooms, basements, etc. Using plastic optical fibers (POFs) will significantly reduce costs for these systems. However, POFs are very sensitive to heat. The POF’s maximum operating temperature is 70℃. So, it is difficult to make a daylighting system using POFs that work stably in the long term. In this paper, a new method of eliminating the heat problem in POF-based daylighting systems was introduced. In the design, a UV-IR filter, a secondary optical element (SOE), and small silica optical fiber (SOF) bundles, were included so that the final temperature of the POFs becomes reduced to 56°C from 266℃ while the ambient temperature is 35℃. This result is promising enough for POF-based daylighting systems to be installed practically. Standardization of this method for a fiberoptic daylighting system will be implemented in the near future.

Fibre optic daylighting systems are a developing technology that offers solutions to daylighting designers. However, these systems are rarely used in the tropics because of the variable illumination provided by the sky, which changes with latitude, time of day, and seasons. This study examines the illumination levels obtained using a fibre optic daylighting system under various tropical climate conditions in Malaysia. A Parans SP3 fibre optic daylighting system with 10-m cable was used on a full-scale test bed model in Universiti Sains Malaysia as an empirical approach. The following results were obtained: (i) on sunny days with intermediate blue sky, the system worked at 79% and reached a maximum of 725 lx, an average of 457 lx, and a minimum of 98 lx; (ii) on moderately sunny days with intermediate mean sky, the system worked at 48.5% and reached a maximum 685 lx, an average of 439 lx, and a minimum of 80 lx; (iii) under overcast skies, the system worked at 37.5% and reached a maximum of 538 lx, an average of 305 lx, and a minimum of 41 lx. These findings provide benchmarking directions for the application of fibre optic daylighting systems in Malaysia.

The primary objective of this study was to develop a fiber-optic hybrid day-lighting system for mobile application such as military shelters in order to cut energy use and the use of fossil fuels. The scope included the design, development, and testing of a hybrid lighting system that is capable of producing about 16,000 lm output with design challenges including light-weight, compactness, and optics that can tolerate a high tracking misalignment. The designed system is comprised of two subsystems: the solar collector and the solar hybrid lighting fixture (SHLF). The solar collector, consists of a housing, a structural stand (tripod), a dual axis tracking system, Fresnel lenses, secondary optics, and fiber-optic cables. The collector is a telescoping aluminum box that holds eight 10-in diameter Fresnel lenses, which focus sunlight onto eight secondary optics and deliver uniform light to the fiber-optic cables. The secondary optics have filters to block UV/IR. The optics has been designed to have a high half-acceptance angle of 1.75 deg and can accommodate a tracking accuracy of 1.50 deg or better. This novel SHLF consists of two components: a solar fiber-optic system and a light emitting diode (LED) system. The fiber-optic cable is coupled to an acrylic light diffusing rod that delivers the sunlight into the room. During sunny periods, the solar fiber-optic lighting could provide full illumination level. In order to keep the same level of lighting during cloudy periods, the LED portion of the light fixture can supplement the output of the SHLF. A compact, light-weight prototype system was built and tested. The results showed that the system's output per lens for the 20 ft cable was about 1750±50 lm at a global solar illuminance of 115,000 lx. The total system was capable of delivering 14,000 lm of sunlight.

Fiber-optic daylighting systems have been shown to be a promising and effective way to transmit sunlight in the interior space whilst reducing electric lighting energy consumption. To increase efficiency in terms of providing uniform illumination in the interior, the current need is to illuminate optical fiber-bundle with uniform light flux. To this end, we propose a method for achieving collimated light, which illuminates the fiber-bundle uniformly. Light is collected through a parabolic concentrator and focused toward a collimating lens, which distributes the light over each optical fiber. An optics diffusing structure is utilized at the end side of the fiber bundle to spread light in the interior. The results clearly reveal that the efficiency in terms of uniform illumination, which also reduces the heat problem for optical fibers, is improved. Furthermore, a comparison study is conducted between current and previous approaches. As a result, the proposed daylighting system turns out convenient in terms of energy saving and reduction in greenhouse gas emissions.

Design of parabolic solar daylighting systems based on fiber optic wires: A new heat filtering device

As a developing country, Malaysia requires innovation to keep abreast of the rapid growth of technology to meet the highly demanding energy consumption. The application of daylighting systems especially by fibre optics is very limited, due to the absence of relevant knowledge and the lack of understanding of the system requirements and potentials, particularly the technology of illuminating enclosed spaces which are totally surrounded by internal walls (opaque). Thus, the aim of this literature review is to shed light on this new approach and to help the building technologists activate its application in building interiors. This paper presents and summarises the important technical issues that enhance the adoption of this technique for the Malaysian built environment.

Development of a fiber daylighting system based on the parallel mechanism and direct focus detection

Different direct solar harvesting systems for daylighting are being explored to achieve high uniform illumination deep within buildings at minimal cost. A promising solution to make these systems cost-effective is the use of plastic optical fibers (POFs). However, heat-related issues with low-cost POFs need to be addressed for the widespread adoption of efficient daylighting technologies. Previous studies have explored solutions for this overheating problem, but their effectiveness remains uncertain. This study proposes a low-cost fiber optic daylighting system integrated with a newly patented mechanical component designed to secure the fiber optic bundle at the focal point, providing three levels of heat filtration while ensuring uniform illumination. Our methodology involves selecting a small area, installing the setup, and measuring both heat and light readings, followed by validation through software simulations. The operational principle of this technology is explained, and experimental tests using lux meters and infrared thermometers were conducted to investigate the system’s characteristics. The three-level heat filtration device reduces temperature by approximately 35 °C at the surface of the optical fiber, and the average illumination of the room is around 400 lux. These results were further verified using RELUX simulation software. The findings demonstrate the promising potential of this new device in solar heat filtration and achieving uniform illumination. Recommendations for mitigating overheating damage and exploring heat filtering possibilities in new parabolic solar daylighting systems for further research are also provided.

A solar fiber daylighting system without tracking component

A set of candela distribution curves(CDCs) were generated for a fiber optic dish daylighting system by Photopia under clear sky conditions at different solar altitudes. The candela distribution curves were then exported to Radiance for photometric analysis of a windowless lecture room. Observations were made on the Radiance rendered illuminance images, which provided photo realistic scenes varying with solar altitudes. If no tracking error were assumed, the daylight collection efficiency of the system remained at a constant value of 68.4% during its operation. Higher the solar altitude angle, greater in photometric quantities were observed, which are represented by candela(cd) and total lumens(lm). In all cases considered, however, the angle of light distribution remained fixed reflecting the solar tracking feature of the system. The illuminance uniformity on the workplane lingered around 0.12, which is quite low. This is quite a contrast to its average value of 0.68 of the area directly below the terminal device (diffuser) of the system. The maximum illuminance of 1,340lux was obtained at a solar altitude of 80 degrees.