# Development of an Energy-Efficient Smart Socket Based on STM32F103
## 2 Literature Review  
Over the decades, great efforts have been devoted to the reduction of greenhouse gas (GHG) emissions, which is commonly recognized as a major contributor to global warming and climate change [2]. As energy conservation is responsible for a considerable amount of GHG emissions, energy-efficient design and standby waste reduction become a key element in the production of customer electronics. Meanwhile, serials of policies and regulations have been issued by governments with financial support provided to encourage energy-saving design and manufacturing of customer electronics [3; 4; 5]. One important regulation is the ECN 1275/2008, issued by the European Commission (EC) on 6 January 2010, which clarified the standby (off mode) and standby plus (mode providesinformation or status display in addition to possible reactivation function) consumptions of household and office electrical appliances. According to the statement of this regulation, the standby power consumption of electronics should be less than 1 watt, while that of the standby plus should not exceed 2 watts. In addition, closing mode and/or standby mode is required as a compulsory integration of electronics. This regulation was further developed to limit the standby and standby plus consumptions to 0.5 watt and 1 watt on 6 January 2013, respectively [4]. As to the occupant's engagement in energy saving, pioneer studies found that energy consumption monitoring and reminding would be an effective way not only for occupants' education, but also for their behavior changes. A study conducted in Reference [6] proposed an outlets system which can be remotely controlled and monitored by the short message service of a GSM cellular phone. Reference [7] established a web-based system, which can control the on/off mode, as well as schedule the operation automatically (once a week or once a day) of power sockets through internet communications. The developed system can also calculate the power consumption and associated expenditures for the controlled power sockets. The target was to remind occupants with energy consumption details, which was then expected to encourage them into taking energy saving action. The studies in References [8; 9] were focused on consumption monitoring and energy-efficient control. Reference [10] proposed a web-based energy management system, which can display the status of appliances and important event information on a touch screen, as well as realize remote control boosted by web ends. A home energy management system was presented in Reference [11]. In this system, real-time easy-to-access information about appliance energy consumption can be provided, with intelligent control strategies and optimization applied locally. Review on recent studies also indicated that demand side management (DSM) has found an effective way contributing to the energy saving at built environment. [PERSON] et al. presented a study of DSM in smart grid networks built on reinforcement learning [12]. [PERSON] and [PERSON] demonstrated an outlook in DSM and smart loads with a review of current studies [13]. A great number of intelligent control systems have emerged to support the energy saving of electric appliances in recent years. One important application is the active intelligent power control system built on sensors network. In this type of system, multiple sensors were employed to locate the zones and detect the relevant activities of occupants, and microcontrollers will then the response to the power control of appliances with the received sensor data and programmed control logic. For example, an intelligent power management system was developed in Reference [14] where an automatic system integrated with light sensors and microchips was used for lighting control. In this system, all the controlled zones were equipped with light sensors, and the intelligent system would apply lighting controls based on the detecting results sent by sensors. The Reference [15] worked on the standby energy reduction of electric devices.