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Abstract: Hong Kong is a densely populated metropolitan city with limited land supply. The land cost is high. Majority of the residential buildings are developed into high-rise with a central core design of enclosed lift lobbies without natural lighting. Electricity is required to provide illumination continuously for 24 h. A remote source solar lighting system using side-emitting fiber optic as illuminators is designed to reduce the emission of greenhouse gases for providing illumination to these lift lobbies. Experiment was carried out to test the performance of the daylighting system and proved that the remote source solar lighting system could displace an average of 3 h of electric lighting in a day and reduce 6.7 × 106 kg of carbon dioxide emission in a year. A study on the cost of the remote source solar lighting system was conducted and compared to the cost of the conventional lighting systems. Both the maintenance cost and environmental benefit that could be offered by the remote source solar lighting system were also studied in detail. Although the side-emitting technology of fiber optic is still primitive, further development can improve the emission efficiency and allow the remote source solar lighting system to operate more effectively. The potential of applying the remote source solar lighting system to conserve environment is promising. [Copyright &y& Elsevier]

Abstract: This research investigates the design constraints and potential of applying the remote source solar lighting system to the enclosed lift lobbies of high-rise residential buildings in Hong Kong. No natural light is usually provided to these lift lobbies, which depend on electric lighting for illumination. The application of conventional light pipes requires minimum 3m headroom and is not feasible to be applied in the high-rise residential buildings of 2.8m floor height in Hong Kong. A remote source solar lighting system is specifically designed to solve the headroom problem. The daylighting system uses small diameter side-emitting fiber optic as light transmission medium. The factors of solar altitude, solar azimuth angle and solar irradiance are investigated. The shadowing effects caused by neighboring buildings and the supporting framework are analyzed in details. Design parameters of the natural daylight system are defined. Design guidelines and a model design are developed as a reference for building designers in designing a remote source solar lighting system. The design addresses both the functional application as well as the esthetic design. The remote source daylighting system can be integrated into the architectural design of the external facade and lift lobbies. [Copyright &y& Elsevier]

Abstract: In metropolitan cities like Hong Kong where land value is high, highrise commercial and residential buildings with “central core” design are developed. The lift lobbies in the buildings are usually located in the centre of the building to free up peripheral areas to provide valuable exterior view. The lift lobbies have no window provisions and electric lighting is switched on for 24h continuously consuming non-renewable energy. Different types of light guides/light pipes have been proven to be capable to transfer daylight into deep floor plan during both clear sky and overcast periods. However, the thickness of light guide requires 3m headroom clearance for installation whilst the headroom of the highrise buildings is usually limited to 2.8m in order to build more storeys. In this research, a remote source lighting system (RSL) is introduced to illuminate the enclosed lift lobbies. The system composed of prismatic light pipe and optic fiber to address the problem of limited headroom. Simulation of the system was carried out and reported in the paper, indicating that this lighting system can solve the energy consumption problem in the lift lobby in terms of renewable energy use and natural lighting application. This research concentrates on highrise residential buildings. [Copyright &y& Elsevier]

Abstract: This paper reports the investigation results of the energy payback time (EPBT) and greenhouse-gas payback time (GPBT) of a rooftop BIPV system (grid-connected) in Hong Kong to measure its sustainability. The 22kWp PV array is facing south with inclined angle of 22.5°. The hourly solar irradiance and ambient air temperature from 1996 to 2000 were used as weather data input. The annual power output was found to be 28,154kWh. The embodied energy for the whole system in the lifespan was 205,816kWh, including 71% from PV modules and 29% from balance of system (BOS). The percentage of embodied energy for silicon purification and processing reached 46%. The EPBT of the PV system was 7.3years, and the GPBT was estimated to be 5.2years considering fuel mixture composition of local power stations. This paper also discussed the EPBTs for different orientations, ranging from 7.1years (optimal orientation) to 20.0years (west-facing vertical PV façade). The results show that the ‘sustainability’ of a PV system is affected by its installation orientation and location. Choosing locations and orientations with higher incident solar irradiance is one key for the sustainability of BIPV technology applications. [ABSTRACT FROM AUTHOR]

Abstract: The shading-type building-integrated photovoltaic (BIPV) claddings can act as power generators as well as external shading devices of a building, which reduce the energy consumption of the building. However, there is little information about energy impacts of different tilt angles of the shading-type BIPV claddings. By considering the typical meteorological conditions of Hong Kong, the energy performance of the shading-type BIPV claddings, in terms of the electricity generation and the cooling load reduction, is analyzed in this paper. The optimum tilt angle of PV modules for maximum electricity generation is found to be 20° instead of local latitude. Combining electricity generation and cooling load reduction, it can be concluded that the optimum tilt angles for the first type of the shading-type BIPV claddings vary from 30° to 50°, while the optimum tilt angle for the second type is 0°. [Copyright &y& Elsevier]