## 2 Overview of the Proposed Concept  
The proposed concept provides detailed information about the individual and total consumption values of appliances to end-users in real time for increasing their knowledge and awareness of their energy consumption, and hence for changing their consumption behaviors. The interface also provides essential and tailored information about the planned DR events to both end-users and system operators. Due to its real time interaction ability, the system operators can observe the decisions of all end-users on the same screen immediately after their choices and then can take an action accordingly. For the purpose of better explaining the concept of the adopted structure, its general scheme is illustrated in Figure 1.  
As shown in Figure 1, a two-way information flow or an information exchange is performed between the system operator and end-users. The system operator sends DR event signals to the end-users to request their availability and make the optimum energy management plan depending on the responses received from them. As stated in the previous section, this communication is carried out through a mobile application, which is the most straightforward and logical way among the other possibilities. The basic concept of the proposed mobile application for end-users can be seen from Figure 2.  
Figure 1: General scheme of the proposed structure. Figure 2: Schematic illustration of the proposed interactive interface. In the proposed user-side interface, first, the specifications of the planned DR event such as its starting and ending times are sent to the end-users and then the convenience of each end-user is demanded. For the ones that accept to participate in the DR event, the appliances to be involved in the program are requested. The responses of all the end-users are then immediately transmitted to the interface developed for the system operator. The interface specific to system operator also includes some other required information such as the total flexible load and the remaining time for the DR event. Based on the remaining time, a few periodic reminder notifications are sent to the end-users that have not responded the invitations yet. It is noted that an automatic response is also available for end-users for predefined appliances and/or periods. When the DR event starts, the system operator controls some or all of the appliances allowed, depending on the required demand reduction during the related period. The appliances are mostly controlled by switching operations (i.e., ON/OFF control); however, the thermostatically controllable loads (TCLs) such as heating, ventilation and air conditioning (HVAC) units and water heaters can also be controlled via smart thermostats. In order to better explain the procedure followed in the study, the main steps of the proposed concept are presented in Figure 3. The whole process can be described more clearly by dividing it into six subsystems. In the first block showing the first subsystem, MySQL database (version 5.7.18, 2017), which can be accessible from the main server only, store events and user data. In the second block named as hypertext preprocessor (PHP), system operator can create new event and view user data as well as events data from a dedicated program at the system operator side, as shown in Figure 4. It should be noted that only the system operator has the permission to reach these pages and requests from other users are ignored. At the user side, HEM devices are capable of receiving the consumption forecasts and weather information, and of making optimum energy management plans. In the subsequent block shown in Figure 5, the system operator can create a new event, and determine where, when and how long it will be. Furthermore, the administrator can review event data and user data dynamically. Figure 3: General flowchart of the proposed concept.