# Design and Application of Daylight-Based Lighting Controller on LED Luminaire
## 1 Introduction
For the environmental impact, the life cycle assessment (LCA) between fluorescent and LED luminaire reveals that LED luminaire provides approximately 41-50% reduction in Global Warming Potential (GWP) and Cumulative Energy Demand (CED). The LED luminaire can also contribute to less use of mercury in the manufacturing process [14]. The result from the literature review reveals that LED luminaire has a definite advantage over conventional fluorescent luminaires and is suitable to be used in building lighting systems to reduce energy consumption and improve energy efficiency. Another aspect that can improve energy efficiency in a lighting system is lighting control strategies for luminaire. In [15], a controller for LED lighting that used sensors and closed-loop feedback was proposed and could achieve 55% and 62% energy saving in continuous and discrete usage patterns, respectively. Another intelligent control that utilized various sensors with closed-loop feedback for different usage patterns has also been proposed [16]. A highly accurate illuminance model has been used in order to validate the intelligent open-loop control that minimized both energy consumption and the number of required sensors and is discussed in [17]. A new approach in lighting control with LED luminaire using a centralized and distributed control algorithm based on uniform illuminance and an illumination rendering strategy has been proposed in [18] that resulted in energy-saving and user satisfaction. Another research by [PERSON] et al. [19] has also taken user satisfaction into consideration by employing multi-sensor and wireless communication to control light output according to occupancy pattern and environment. A luminaire-based sensing control methodology that utilized both occupancy and light sensors covering working space in order to give the required illuminance level has been proposed in [20]. The control methodologies and algorithms that have been discussed showed the ability to reduce energy consumption in a lighting system, while maintaining the light output on the working plane according to the user. Moreover, energy consumption can be reduced further by utilizing natural light in the daytime to maintain adequate illuminance in a workspace. Daylight harvesting to supplement artificial lights has been constantly developed due to its potential to improve further the energy efficiency of a lighting system, especially integrated with new control strategy and LED technologies. The impact of daylight on interior lighting in terms of energy consumption and various factors such as daylight availability, lighting system layout, and control system has been discussed in articles [21; 22]. In [23], a comparative study between daylight control strategy and scheduling lighting control strategy based on both computer aid and occupancy sensor was conducted. Daylight control had an advantage of maximizing the efficiency during main operating times around 7:30 A.M. to 5:30 P.M. Lighting load reduction in those periods of time can contribute to less energy charge because at those periods, a peak demand charge and higher time-of-day rate were in effect. A simulation of daylight control for an LED-based lighting system has been presented by [PERSON] and [PERSON] [24]. Another simulation that used the Daysim software for evaluating daylight performance has been shown in [25]. Many aspects of control, such as photo-sensor placement, control algorithms, and impact of shading device, have been taken into consideration in the calculation of daylight performance. The result proved that a daylight integrated control system could achieve significant energy savings while maintaining desired illuminance levels. A Controller Area Network (CAN bus) communication protocol has been applied to a daylight control circuit, and a logic method has been used for a venetian blind control in order to reduce energy consumption in an entire building [26]. [PERSON] et al. [27] have proposed LED luminaire prototypes that integrated daylight sensing based on open-loop control.