# Design and Application of Daylight-Based Lighting Controller on LED Luminaire
## 4 Results  
The experiment has been done at the Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang located in Bangkok, Thailand (latitude 13 deg43'45.5'' North and longitude  
Figure 6: Diagram of the daylight control circuit for LED luminaire. Figure 7: Flowchart of the operation of the proposed LED daylight control circuit. \(100^{\circ}46^{\prime}32.0^{\prime\prime}\) East) with the window-side of the experimental setup (with louver) facing the east direction. The experiment has been replicated three time under the same sky condition (clear sky) on the date of 19-21 January 2020 in order to verify the accuracy of the data. The result from the experimental setup in terms of the effect of louver angles on electrical parameters and illuminance at 9.30 A.M. has been obtained from the experimental setup. The relation between the louver angle and various parameters can be illustrated in Figure 8. The electrical parameters consist of voltage, current and power as shown in Figure 8a-c, respectively. When louver angle increases, illuminance from the workplace also rises due to daylight through experimental test room. This result in the control unit tried to maintaining illuminance value at 300 lux as setting value by steady reduced current and power to LED luminaire. The voltage level is steadily rising, but it does not have any effect on control circuit operation. This value has been further decreased as louver opens more than 40 degrees due to high daylight intensity in the workplace. The illuminance characteristics of two luminaire at various louver degrees are illustrated in Figure 9d. From the figure, the value of luminaire 1 came from the luminaire located at the left-side of experimental setup and the value of luminaire 2 was located at the right-side of experimental setup according to Figure 5a. The result shows that illuminance in the case without daylight control circuit has been steadily increased as louver angle increases, and it immediately rises when the louver opens more than 80 degrees. When installing a daylight control circuit, it can be seen that illuminance has been reduced compared to the previous case without the control circuit due to the setting in algorithms that specified illuminance value at 300 lux. Figure 8: _Cont._  
For the actual field test at 1.00 P.M., the experiment data in terms of electrical parameters and illuminance are shown in Figure 10 with the relation between louver angle and various parameters. The electrical parameters are voltage, current, and power as depicted in Figure 9a-c, respectively. When the louver angle increases, the voltage, current, and power have been steadily reduced, and it is immediately reduced significantly when louver opens more than 80 degrees due to increasing illuminance on the workplace from daylight, thus the control circuit reduces power for LED luminaire in order to regulate the light output from artificial lighting. Illuminance characteristics described in Figure 9d show that illuminance in the case without daylight control circuit has been a steady increase as louver angle increases and it immediately rises as louver opens more than 70 degrees. When installing a daylight control circuit, the illuminance is also reduced similarly to the 9.30 A.M. period. This result reveals that louver angles have a significant effect on daylighting control circuit performance over a period of a day. Figure 8: Effect of Louver angle on electrical and illuminance data obtained from experimental setup at 09.30 A.M.: (**a**) Voltage; (**b**) Current; (**c**) Power; (**d**) illuminance on working plane. Figure 9: _Cont._  
The effect of time on daylight control circuit performance is evaluated by obtaining power consumption and illuminance from LED luminaire every 10 min from 9.00 A.M. to 4.00 P.M. The experimental setup is with louver facing east direction.