Smart Building Lighting Automation with DALI
Electrical Electronics Engineer
Today, with the development of technology, many buildings are designed as smart buildings. Smart buildings provide a great deal of convenience for users as well as a very important role for energy efficiency. It is known that 20% of energy in the buildings is spent for lighting, in which case lighting automation is very important for energy efficiency. DALI protocol and lighting automation applications are used frequently due to various advantages. DALI protocol is used in lighting automation applications to compensate daylight in indoor space by using daylight and motion sensors. This system has a great effect on saving energy. This article discusses the DALI protocol and the use of the DALI protocol in smart building lighting automation applications.
Energy efficiency can be defined as the reduction of energy consumption without reducing the quality of life and service standards in buildings and without reducing the quantity and quality of production in industrial enterprises.  Approximately 40 percent of the world’s total energy consumption is consumed as a result of use in buildings. As a result, carbon emissions may be higher than emissions from the transportation sector. Lighting, ventilation, heating, cooling and air conditioning are the biggest energy consumption points in homes, offices and businesses. It is very important to ensure efficiency in energy use in buildings. Building management systems (BMS) automate building services such as cooling, heating and lighting. In intelligent buildings, information and communication technologies are used in the design, commissioning and operation phases to reduce energy consumption. Keeping the energy expenditure of the building at the lowest level without sacrificing user comfort is the most important task of smart buildings. [2-3] Lighting is one of the most important energy consumption items in buildings. Energy can be saved in lighting by making maximum use of the daylight in the environment. Lighting systems consume approximately 20% of electricity consumption in offices and homes. Lighting automation and efficient luminaires can save up to 75% energy. In lighting automation applications, in case of insufficient daylight, daylight and presence sensors are used which turn on the lighting and switch on the indoor areas due to movement. Energy efficiency is achieved by selecting the right lighting automation. And energy consumption can be greatly reduced. DALI protocol is widely used in lighting automation. DALI protocol provides solutions to the simplicity, flexibility and upgradability required in lighting systems. It is also an open protocol and supported by most global lighting control system and component manufacturers. Provides digital control of the lighting system. DALI is a widely preferred protocol because it provides several advantages such as simple and cost-effective installation with standard electrical wiring. [2, 4]
II. WHAT’S SMART BUILDING?
Smart building is defined as a centrally controlled building with communication infrastructure, as well as more comfortable, secure and most importantly energy-saving systems for users. In order to use energy efficiently, the energy consumption of buildings is automatically monitored through the systems in the building. The most important purpose of smart building systems is to increase energy efficiency in buildings, to minimize the energy consumed and to keep the user comfort at the highest level. Most of the total energy consumed in the world and in our country is consumed by heating, ventilation and lighting systems used to provide user comfort in buildings. By automatically controlling these systems, energy expenditures can be minimized. Smart building systems, where many features are combined, work in an organized way with many systems such as building automation system, energy management system, energy control system, central control system and monitoring system. In general, smart building systems have ventilation, air conditioning, fire detection, intelligent lighting and elevator systems, alarm, security, card entry systems. These systems work seamlessly with each other, controlled and managed from a single center. [2,5-8] The most important factors that increase the energy consumption of an average family and cause unnecessary energy consumption are high-level cooling systems, heating systems, unnecessary left-on lamps, unnecessary heated areas at home, and lighting energy losses due to insufficient use of daylight. Various software and hardware systems used in smart houses can be accessed remotely. 
III. LIGHTING AUTOMATION SYSTEMS IN SMART BUILDINGS
Lighting automation in smart buildings provides maximum comfort and convenience while reducing energy consumption for lighting. It is known that 20% of the electricity consumed in the world and in our country is used for lighting. Therefore, lighting systems are an important area where energy efficiency should be ensured. Lighting automation is applied in business buildings such as office buildings, hospitals, stations, airports, shopping malls and fairgrounds, production and storage areas.  Considering the share of lighting in energy consumption, energy efficiency can be achieved to a great extent with the correct lighting automation. DALI is of great importance at this point.  DALI protocol is easy to implement, practical and suitable for energy efficiency. Integration into building automation systems is possible. This integration requires computer software and appropriate interfaces. DALI protocol is designed as a common standard in the lighting industry. Its simplicity will replace analog systems over time. 
IV. DALI – DIJITAL ADDRESSABLE LIGHTING INTERFACE
DALI consists of the first letters of the words Digital Addressable Lighting Interface. Digital addressable means lighting interface. This protocol complies with IEC 62386 standard. The IEC 62386 standard is an international standard defined to control and manage lighting elements easily and intelligently. DALI is an improved version of DSI (Digital Serial Interface) developed by TRIDONIC in Austria in 1991. Many ballast manufacturers develop devices that support the DALI system. These companies are gathered under the roof of DALI AG. DALI protocol, which is prepared by various lighting companies in a common framework, has a wide range of products. The system equipment used does not need to be the product of the same company as it supports a common protocol. The installation and electrical installation of the devices used in the system are simplified. DALI protocol provides monitoring and control of many equipment such as emergency lighting kits, ballasts and LEC kits. DALI protocol is preferred by most users and is widely used in the market due to its robust structure, flexible solutions and ease of use. DALI interface allows more functionality with fewer components. [6,9,11]
V. HOW DOES WORK DALI PROTOCOL SYSTEM?
A simple DALI line system consists of a master module, compatible lighting modules (slave) and a power supply. All lighting devices in the DALI network can be controlled individually or in groups. The master module can be connected and controlled up to 64 different addressable slave modules. Each lighting module in the DALI network has a short address between 0 and 63. Up to 32 groups (16 principal and 16 virtual) can be grouped and a slave module can be grouped into several groups. 16 different scenarios can be created in each group. If more than 64 devices need to be controlled, more than one master device must be used. By means of commands sent to the network, the lighting module can be switched on, off, dimmer and the power level values of the modules and the fault information of the lamps can be obtained. The devices connected to the network are configured via the DALI line. In addition to lighting commands, configuration commands can be used for addressing, network integration, device scanning. Figure 3 shows the DALI network connection diagram. DALI communication is performed between the master module and the slave module. The communication between the master module and the automation system is done with the protocol used in the automation system (such as TCP / IP protocol). In the DALI network, communication takes place via two lines that provide a difference signal. There is no polarization restriction on the DALI line. The line supply is provided by a separate power supply, not devices. The voltage difference between the lines is read as low and high level. 6.5V and below (lower limit-6.5V) is low. 9.5V and above (upper limit 22.5V) is defined as high level. When the slave devices in the DALI line switch the line via a short circuit, the power supply must supply a maximum current of 250 mA so as not to damage its equipment. The cable to be used in connection should not exceed 300m. It is possible to connect multiple DALI lines. [12,13]
VI. DATA TRANSMISSION WITH DALI
DALI uses its own protocol for communication. The command to be sent according to DALI protocol consists of 1 start bit, 16 data bits and 2 stop bits. The content of the 16-bit data sent is 8-bit instruction and 8-bit is address information. The incoming reply command consists of 1 start bit and 8 data bits (incoming answer) and 2 stop bits.  Manchester coding was used for data coding. There is a logic of 0 on the vertical edge and 1 on the rising edge. Figure 5 is shown.  VThe DALI line is fixed at logic 1 when no data is transmitted. The line is supplied constant by the power supply. Each bit duration is 833 μs. This 833 μs bit time has a maximum deviation tolerance of ± 10%. A clock cycle of 416 μs should be used to obtain a bit time of 833 μs. The maximum rated bit (MSB) is transmitted first. In DALI protocol, information transmission is 1200 bits per second. There are two types of data frames in the DALI protocol, the data frame being sent and received. In the example shown in Figure 6, the master sends a message to the line to ask for the level of the slave at address 2. This message is sent to all slave devices on the line. The returned message is only transmitted from the slave device at address 2 to the master device. Figure 7 shows data frames for messages sent and received. 
VII. ADVANTAGES OF DALI PROTOCOL IN LIGHTING CONTROL
If we list the benefits of the system;
Dimmering and switching are done with simple circuits. Dimmer value can be adjusted digitally to desired levels. Dimmering process is logarithmic and therefore suitable for human eye sensitivity. No additional switch is required for switching. The light source can be switched on / off with the DALI command. Lighting scenarios can be made and scenarios can be run at any time. The status of the connected light sources can be monitored with the DALI protocol. (on, off,% x DIM, lamp failed, etc.) The DALI protocol enables intelligent room-based lighting management with optimum component costs and high functionality. Suitable for development, new modules can be added to the system if desired. With the simple data structure, there is no confusion on the data path and no losses occur. Controlled independently of the supply line. In this way, old and new lighting installation can be applied. Provides ease of use with its simple structure. The control line has no polarity and is easy to install. It is possible to manage the luminaires in batches or in a single state and the groupings can be changed independently of the wiring. There is no need to switch the supply voltage on and off. Compatible with emergency lighting systems. Compared to 1-10V systems, it is more cost effective and has higher features. Perform individual addressing, group assignment, scenario invocation, and time-based tasks. Remote (IR) control, PIR (Passive IR) control, can be controlled by daylight sensor. Can work with building management systems. [14,15]
In recent years, with the decrease in energy resources and the increase in demand for energy, studies on energy efficiency are very important. Efficient use of energy can be achieved with the right designs and automation solutions in living spaces, office buildings, industrial enterprise buildings where energy consumption is high. Smart building systems, which are becoming widespread today, are of great importance for energy efficiency. In smart building systems, building control systems can be installed easily managed by users through central automation systems. The comfort and energy savings provided by these systems can enable the system to pay for itself in a short time. Energy efficiency not only ensures sustainable business success but also contributes positively to climate change. The energy used for lighting accounts for approximately 20% of electricity consumption in buildings. The energy used for lighting can be used efficiently by using the maximum level of daylight and with lighting automation systems. DALI, an international protocol for digital lighting control, is a widely used standard in lighting automation applications in the market thanks to the advantages it provides to users and designers. It is possible to develop this protocol. In the coming years, the use of smart building systems is expected to become widespread and improved. In addition, it is foreseen to develop smart building lighting automation systems.
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