Natural and Artificial Lighting Systems

The objective is to enhance the quality of indoor spaces and cut energy consumption through optimizing the use of daylighting and minimizing the need for artificial lighting. Studies have shown that access to daylight and views provide a feeling of well-being. Adequate daylight can easily be introduced to the depth of inside spaces up to 4.6 m (15 ft) with conventional height window. Other experimental advanced daylight systems can passively redirect sunlight to larger depths (4.6-9.1 m, 15-30 ft) using special technologies such as HOE (i.e., holographic optical elements), articulated light shelves, and light pipes. The advantages of these systems are: (1) to increase the daylight illuminance levels at deeper spaces with minimum solar heat gain, and (2) to improve the uniformity of the daylight luminance distribution across the room under variable solar conditions throughout the year. Narrowing the width of floor plate to approximately 14 m (i.e., external wall to wall width) can help to reduce artificial lighting and optimize natural lighting. A room with a height-to- depth ratio of 1:2 with 20 % glazing of its external wall area allows good light penetration (i.e., 1.5-2 daylight factors) and can be described as cheerfully daylit. In achieving an acceptable comfort level of daylight, one of the discomforts to be recognized and resolved is the problem of glare. Treatment of this problem requires a lighting strategy and has an implication on energy performance.

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