Integration of a remote source solar lighting system into the architectural design of enclosed lift lobbies in high-rise residential buildings

Abstract

Due to high land cost and plot ratio requirements, residential buildings are developed into high-rise central core design in which the lift lobbies are enclosed without natural lighting and the floor height of a residential building is limited to 2.8 m. In conventional remote source solar lighting system, metallic and prismatic light pipes are used as common light transfer mediums. However, the sizes of these light pipes have considerable diameters usually more than 450 mm, and require minimum 3 m headroom clearance for installation. Such headroom requirement is not feasible for the high-rise buildings in Hong Kong. This research is to develop an advanced remote source solar lighting system using side-emitting fiber optic of 10 mm in diameter to transfer natural lighting into the lift lobbies and investigate the potential and energy performance of the application to reduce energy consumption for providing illumination for the enclosed lift lobbies of high-rise buildings in Hong Kong and other countries. Simulation and experimental study were carried to study the performance of the proposed daylighting system and analyze the factors that could affect the efficiency of the remote source solar lighting system. As Hong Kong is a densely populated city with majority of buildings developed into high-rise buildings, the shadowing effect from neighbouring buildings was also analyzed. An installation method was proposed to solve the shadowing problem. The remote source solar lighting system was designed to satisfy both the functional and aesthetic aspects. Design guidelines and flowchart were formulated as a design references for building professionals in applying remote source solar lighting system into high-rise buildings. Finally, cost analysis of the remote source solar lighting system was carried out. The payback period is about 5 years. The maintenance cost and the environmental benefits offered by the proposed daylighting system were also studied. The remote source solar lighting system can reduce 6.7x 10⁶ kg of carbon dioxide emission in a year. Although the side-emitting technology of fiber optic is still in a very preliminary stage of development and transmission efficiency is very low, the proposed remote source solar lighting system can still provide daylight for an average of 3 hours of 150 1x in a day. Further development in the application of RSSL is proven to be worthwhile. The research findings can provide information for further research on application of remote source solar lighting system. The application of the proposed RSSL is anticipated to be able to extend to provide illumination to interior spaces of other buildings as well when the technology becomes mature.