**4. Smart utilization of background lights for efficient indoor lighting intensity control**

The ways which are used today in order to light houses, offices, and most of indoor areas are inefficient as a lot of energy is consumed unnecessarily during the day time. This problem is also one of the design concern in Green Building. In this section, a solution to this problem and a method for people's comfort is presented. Lights switch on automatically when there is somebody in the room and switch off when there is no occupancy. In addition to this known technique, adjustment of the brightness level of the lights will be possible via the personal computer or any other smart device. In this method, for the illumination of the lights in the area, where is needed to be controlled, light automatically is measured by sensor and considering the amount of background light coming from outside, the brightness of lights automatically controlled to reach the preset level. By the means of this method, it is possible to provide both user comfort and energy saving [35].

#### **4.1 Survey and problem definition**

The energy wasting created by lighting is very significant in places where is multi-occupant, especially in offices. In Today's world, a lot of companies provide methods in order to minimize energy consumption, because energy consumption becomes a significant problem in developing world. Many researches show that lighting system accounts for approximately 30% of energy consumption [36]. Especially, departmental stores and big offices located in city territories causes a lot of energy consumption. In offices, lighting system consume approximately twice more than printers and computers [37]. One of the main causes of this problem is that people leaves lights "on" in unoccupied places. In almost 23% of the daytime this event occurs [38]. Another problem that causes to waste of energy is called over-illumination. Over-illumination occurs when lights are brighter than needed to illuminate room. In addition to this, researches demonstrate that excessive lighting can give rise to negative health effects [38]. This problem, however, still occurs in many structures everywhere, particularly in offices. Researches indicates that lights are off for just 1 percent of daytime while the room is unoccupied [39]. And this fact shows that over-illumination occurs during daytime because of external daylight coming into the room. And, in order to overcome these problems, implementation of intelligent lighting system can be a great solution.

The direct advantage of automated lighting system is to reduce energy consumption and maintenance cost. Energy consumption is reduced, because intelligent lighting system considers external daylight coming into the room and occupancy status, hence reduce the amount of power consumed. And, maintenance cost is minimized, since lifetime of the light bulbs is better utilized and this factor

#### *Economic Applications for LED Lights in Industrial Sectors DOI: http://dx.doi.org/10.5772/intechopen.95412*

extends the life span of light bulbs. In addition to this, indirect advantages of proposed solution are that it allows the country to export more oil and gas, since the consumption of fuel that is needed to generate electricity will be reduced due to the energy savings caused by intelligent lighting system. Also, a reduction in pollution can be considered as positive advantage as well, because when less energy is consumed, the amount of carbon dioxide emission released by power generation plants is reduced.

It is important to highlight that during the engineering phases of indoor lighting system, because of uncertainty of the amount of daylight and any other background light which penetrates the room, engineers ignore this factor in the design which consequently introduce several drawbacks in the operation and maintenance cost of lighting system. Typical level of illuminance for indoor lighting is given in **Table 12** [35].

It is clear from the minimum level of illuminance indicted in **Table 12** for each application that the design engineer has to consider the given value as Minimum. This make the designer not only ignore any background lighting contribution, but also it considers "Minimum" illumination level that allows the designer to go to higher values to satisfy other design criteria such as symmetrical distribution of lighting inside the room. Also, this "Minimum" value of the illuminance level considered the worst calculation safety-factors that may not be applicable in all cases. Therefore, in general, most of the time in day extra unnecessarily lux level can be obtained inside the room, and hence additional money for operation and maintenance need to be spent.

For better control of the indoor lighting and reduce the operation and maintenance cost of the lighting system, there are many methods to implement intelligent lighting system in order to provide more efficient lighting [40]. First method is to use occupancy sensor in offices, homes etc. In this method, sensor is used to detect occupancy in order to control lights. If there is somebody in the room, lights switch on, otherwise lights switch off automatically. This is a good straight forward and easy method reduce energy consumption but it is not the optimum solution as the method still ignoring the contribution of background lighting, therefore it cannot be considered as high efficient way to control the indoor lighting intensity.

Second method is to utilize daylight to adjust brightness to a preset level. Energy savings are controlled by using dimming technique in which percentage of illumination of light bulbs change according to daylight coming into the room. Researches show that dimming technique reduces energy consumption up to 30% compared to non-dimmable light bulbs [41]. Daylight utilization can be accomplished by using light sensors which is used in order to detect level of illuminance inside the room and adjust brightness of the light bulbs on the basis of amount of daylight measured in the room and desired set-point. The energy saving can increase depending on the performance of light sensors used. It is reported by Electric Power Research


#### **Table 12.**

*Design average level of illuminance for various places.*

Institute that daylight utilization can increase energy savings up to approximately 40% [42]. In addition, researches indicate that energy savings can enhance up to 76% by taking into account daylight and occupancy status [43].

lights. Light intensity sensor(s) is used to give the controller the required data. The control unit sends signal to light dimmer(s) to control the LED light imitation

The term called intelligent luminaire is connected to a smarter level of illumination where devices are capable of creating lighting comfort, energy efficiency, and easy controllability. The concept which is named intelligent lighting system corresponds to a system that communicates and cooperates with many luminaires, creating a node that satisfies user requirements. The key goal of this kind of system is to save energy and, at the same time user comfort by the means of network communication. In **Figure 9** the block-diagram of intelligent lighting system is illustrated. It is assumed that lighting system is dimmable (controllable) in order to provide intelligent method to tune the Lux level to the present value determined by

Firstly, this system checks for occupancy. If there is no occupancy, Arduino controller sends commands to AC light dimmer (which is controlling the intensity of light bulbs) to switch off lights. If there is somebody in the room, PIR sensor detects occupancy inside the room and activate Arduino controller. Consequently, the controller sends signal to the dimmer(s) to switch on the light and tune the lux of the room to achieve the preset value based on the input provided by the light

The intelligent lighting system contains PIR sensor, BH 1750 light sensor,

PIR sensor is used to detect occupancy in the room. Light sensor is used to measure the amount of light in lux. Arduino Mega is used as a controller. Ac light dimmer is used in order to adjust the brightness of LED bulb. To monitor the amount of light (PV) and set point (SP), LCD is used. LED bulb is used to provide

this type of sensor is widely used around the world. It is capable of measuring various air temperatures in the room. When there is somebody in the room, sensor sends a signal to turn on or off lights. When object is moved in the sensor's field of view, infrared lights which is radiating from the objects are measured by PIR

PIR sensor is one of the simplest and inexpensive type of occupancy sensors and

to achieve the preset Lux level required for the room considering daylight.

*4.3.1 Intelligent lighting systems methodology*

*DOI: http://dx.doi.org/10.5772/intechopen.95412*

*Economic Applications for LED Lights in Industrial Sectors*

*4.3.2 Intelligent lighting system components*

*Block diagram of intelligent lighting system.*

illumination in the room.

Arduino Mega, AC light dimmer, LED and light bulb.

the controller.

intensity sensor(s).

**Figure 9.**

**45**

In this section, both above mentioned approaches are considered to develop intelligent lighting system in order to minimize power consumption and provide sustainable lighting system. Economic analysis is required to be carried out to evaluate this new approach.

This integrated approach enables us to adjust brightness of lamps to a preset level, considering daylight coming into the room and also prevent unnecessary lighting in unoccupied places. In the economic analysis, LED lighting type is selected as its power consumption is the lowest among other types of light bulbs, and hence it is expected minimum energy cost saving to be achieved. In case, other type of bulb is used, such as fluorescent or incandescent bulb, the energy saving due to using this intelligent lighting system shall be much higher.

#### **4.2 Lighting control procedure**

Energy consumption can be reduced significantly when light bulb's output is controlled automatically. Two methods are commonly used for lighting control. First method uses individual lighting control system in which each light bulb's output is adjusted independently according to light output level of its neighbor bulbs, the second method is networked lighting control system, which is more effective than the first method because all bulbs communicate intelligently with each other in order to achieve the required level for the room light intensity.

Networked lighting control system can be classified as DLCS (distributed lighting control system) for first method, or CLCS (centralized lighting control system) for second method. in DLC systems, each light bulb's sensing data is received by the controller, and they can communicate with neighbors in order to adjust their output level according to each other's state. However, in central unit CLCS which receives the status of each node based on information obtained from the sensors, and then performs control actions via actuators. In this system, central unit determines the output level of each light bulb on the basis of data obtained from sensors. In CLCS, many tasks are performed by central unit, such as, acquiring sensors' data from each node, estimating the optimal state where each light bulb will meet light requirements of the room (**Figure 8**).

**Figure 8.** *C LC system and DLC system.*

#### **4.3 System description**

PIR (Passive infrared) sensor is used to sense occupancy in places. PIR sensor detects occupancy at places and send commands to the controller to switch on or off lights. Light intensity sensor(s) is used to give the controller the required data. The control unit sends signal to light dimmer(s) to control the LED light imitation to achieve the preset Lux level required for the room considering daylight.
