The authors propose an interface for home energy management system (HEMS). This interface is aimed at raising the energy-saving consciousness of users who have little knowledge of energy saving. A possible reason for the low level of consciousness of such users is that HEMS does not provide information which helps users in energy-saving planning. To help users who have insufficient knowledge of energy saving, the interface visualizes power consumption and operational information obtained from network home appliances. In order to show which appliances have potential for significant energy-saving effects, the interface uses icons that visually represent high-power appliances whose power consumption exceeds 400 W, along with their operation periods. By viewing the screen, users can easily recognize how to operate appliances for energy-saving planning as well as which appliances have high energy-saving effects. The authors have developed a tool with a built-in interface and have evaluated it by questionnaire.
TopIntroduction
Electric power occupies almost 50% of the amount of household energy consumption. In view of this, the use of home energy management systems (HEMS) for household energy management has been promoted. The HEMS has two major functions: visualization of power consumption and remote control of home appliances. By utilizing this technique, an energy-saving effect of 3 to 12% can be achieved (Kato, 2011). The visualization of power consumption by the HEMS is aimed at promoting the energy-saving awareness by presenting the state of use of electric power so that users can find better energy-saving methods and realize how effective those methods are. The remote control of home appliances is aimed at assisting users’ energy-saving actions by offering the function of remotely controlling home appliances through a single terminal device. However, (Yoshie et al., 2014) have revealed that users with a high level of awareness of energy saving tend to frequently use HEMS, whereas users with a low level of awareness of energy saving use it rather infrequently. Additionally, a practical experiment demonstrated (Osaka City, 2013) that the energy-saving effect by a HEMS system was as high as 22% immediately after the introduction of the system, but decreased to 11% over a period of three months. A probable cause of this decrease in the energy-saving effect is a decrease in the usage rate of the system. We considered that such a decrease in the usage rate occurred due to cumbersome tasks for the energy-saving. Accordingly, studies for assisting energy-saving actions without requiring cumbersome tasks have been made.
Accordingly, methods for assisting users with little knowledge of energy saving have been studied. (Hidenori et al., 2014) and (Yusuke et al., 2010) have proposed a system which provides general advice concerning energy-saving based on power consumption and peak time. This system has an advice list and selects a piece of advice which is likely to produce the highest energy-saving effect for the user based on that list. However, this advice is not optimized for the use condition for each individual user, so the energy-saving action may be burdensome for the user. (Morimoto, 2016) and (Takekazu et al., 2013) have proposed energy-saving methods by an automatic control of home appliance products. Their ideas do not take into account external factors, such as seasonal variations, weather, and time of day.
The use of a system which proposes energy-saving methods or automatically controls home appliances as in conventional studies is likely to cause users to feel the energy-saving tasks burdensome and tend to infrequently use the system. We believe it is necessary to develop a HEMS which can motivate users to voluntarily act on energy saving without feeling reluctance for such actions. To this end, the so-called nudge theory will be useful, which is a technique for appealing to direct reaction and inducing individuals to change their behavior, sometimes involuntarily (Thaler et al., 2008). We consider the induction of the behavioral change according to the nudge theory to be important. So, we will include the idea into our proposed method to develop a HEMS capable of managing energy-saving actions in an intuitive form without requiring users to do cumbersome tasks.