UTILIZATION EXAMINATION OF THE TASK AND AMBIENT LIGHTING AND CORRIDOR LIGHTING USING LED LIGHTING APPARATUS

摘要

At present, LED lighting units still present much lower luminous efficiency and luminous flux,require far higher cost than fluorescent lamp lighting units and are yet to be widely used. However, it is regarded as meaningful to develop prototype models of LED lighting units and examine their potential for practical use at this stage and focus has been given to task and ambient lighting in offices and corridor lighting as lighting units that can take advantage of the benefits of LEDs and are believed to be feasible in the near future. For this paper, prototype models of individual lighting units and a visual environment measurement system have been developed and the evaluation of visual environment as well as measurement of power consumption have been carried out by installing lighting units in actual room for studying their practicability. Specifically, methods of lighting that are likely to improve visual environment were devised and the evaluation of visual environment including sensation of room brightness and glare and measurement of luminance distribution were conducted as the methods were embodied using LED lighting units, which were compared with those for the conventional lighting method using fluorescent lamps for the purpose of study. As a result, task and ambient lighting and corridor lighting that use LED lighting units have proved to provide equal or better visual environment (improved sensation of room brightness, reduced glare, etc.) with less luminous flux as compared with fluorescent lamp lighting, a common conventional lighting method. However, the luminous efficiency of white LEDs mounted on the LED lighting units was not very high at approximately 30 Im/W, which means that power consumption of LEDs is equivalent to or higher than the conventional fluorescent lamp lighting at present, and energy-saving effect cannot be readily achieved. The luminous efficiency of white LEDs is improving year after year and expected to reach 120 Im/W, which is four times as much as with the LEDs used for the present study, by 2011. Use of LED lighting units is expected to offer ample potential for significant energy conservation in addition to the improvement of visual environment in the future.