Energy saving potential and visual comfort of task light usage for offices in Malaysia

In the wake of the recent green building aspiration in Malaysia, this article explores the energy saving potential and user behaviour towards task lights in two office spaces in Malaysia; one is daylight assisted, and another is the conventional design of full reliance on the overhead electrical light. The lighting usage patterns were monitored with 5 min interval over a month's period during office working hours. Task lights with 8W CFL daylight bulbs were provided after the initial two weeks of measuring period and comparison of lighting power density LPD (W/m2) was made. 15 samples of each office space were given visual comfort survey before and after the task lights were distributed to each's workspace. The result reveals that the addition of task lights only contributes to 0.60 W/m2 of LPD. It further concludes the operational LPD of the daylight assisted with task light equipped office space achieves 78% of lighting energy saving (3.04 W/m2) when compared to the recommended base case of MS1525:2014 (14.00 W/m2). It also reveals that the provision of task light will not necessarily improve the current LPD if the lighting control system is not responsive to it to create the desirable luminous environment. Interestingly, both offices' occupants show significant improvement in evaluating their satisfaction towards paperwork brightness and colour rendering with the usage of task light. However, this does not apply to computer work. There is no correlation established between the usage rate of task light and the distance of workspace from the nearest window.