Abstract
Office lighting is vital for energy savings and occupant’s visual comfort being. Energy efficient lighting has been studied extensively in the aspect of daylighting harvesting and task ambient lighting, predominantly in Temperate developed countries. However, the lack of evident on the effectiveness of low ambient task lighting in the Tropics has prompted this paper to investigate the practicality of such lighting design for the Tropics. This paper explores into the office occupant’s mood and preferences of low ambient daylight and usage of task light for the office in the Tropics. It also discusses the recorded work plane illumination level upon the usage of such lighting system. It studies the impact of such lighting design on people’s preference, work plane illumination for three office spaces with the different luminous environment. In regards to the source of ambient lighting, two offices harvest daylight, and another uses the conventional overhead lights in accordance with MS1525 recommendations. Three of the offices have 15 samples respectively and the workspace horizontal illuminance level is measured across a month. The results of before and after the provision of task light reveal that the acceptance for low ambient task lighting system and it is widely preferred. However, the task light is not necessary utilized as some people are adapted to do computer work under low ambient lighting (~50-150lux). It shows that people’s preference for work plane illuminance varies greatly. Many agree that they are in control with their personal lighting environment when an appropriate glare-free task light is being used. The paper recommends that office luminous measurement shall take other lighting parameters such as the vertical illuminance and luminance ratio into consideration for future research.
Highlights
With all the increasing inhabitants and commercialization of which pose increasing the need for building services and increasing time spent in building, office lighting design contributes substantially to the primary domains of energy efficiency and visual comfort
With no sensor loggers in place, it is assumed that all samples are at their desk most of the time. 15 units of TENMARS TM-203 illumination meters are placed on each work plane to record the illuminance level over a month at 5 minutes interval. 4 units of HOBO U12 loggers record the ambient temperature and relative humidity across the office space at 5 minutes interval
The recorded illuminance readings are presented in two ways; an average illuminance trend of selected loggers over the working hours, and Useful Daylight Illuminance (UDI) 100% stacked bar concept proposed by Nabil & Mardaljevic [31]
Summary
With all the increasing inhabitants and commercialization of which pose increasing the need for building services and increasing time spent in building, office lighting design contributes substantially to the primary domains of energy efficiency and visual comfort. With MS1525:2014 as a benchmark reference, this paper compares the post occupancy (POE) visual comfort preferences of the usage of an ergonomic task light for three office spaces with variations in the luminous environment. This is a continuation of a prior working pilot paper which faced limitation in the size of test subjects and measuring period [1].
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