# The Effects of Augmented Reality Companion on User Engagement in Energy Management Mobile App
###### Abstract  
As the impact of global warming on climate change becomes noticeable, the importance of energy efficiency for reducing greenhouse gas emissions grows immense. To this end, a platform, solution, and mobile apps are developed as part of the European Union's Horizon 2020 research and innovation program to support energy optimization in residences. However, to ensure long-term energy optimization, it is crucial to keep users engaged with the apps. Since augmented reality (AR) and a virtual animal companion positively influenced user engagement, we designed an AR companion that represented the user's residence states; thereby making the user aware of indoor information. We conducted user evaluations to determine the effect of the AR companion on user engagement and perceived usability in the context of energy management. We identified that the user interface (UI) with AR (ARUI) barely affected user engagement and perceived usability compared to the traditional UI without AR (TUI); however, we found that the ARUI positively affected one of the user engagement aspects. Our results show AR companion integration's potential benefits and effects on energy management mobile apps. Furthermore, our findings provide insights into UI design elements for developers considering multiple interaction modalities with AR.  
user interface; user evaluation; user engagement; perceived usability; augmented reality; Internet of Things; energy management +
Footnote †: journal: Applied Sciences  
0000-0002-4000-0000-0000-0000-0000-0000-0000-00000-0  
user engagement, an animal companion presented in AR has the potential to benefit the user as well [13]. Meanwhile, AR is also used in energy management studies; however, fostering awareness of energy efficiency using intuitive data visualization [14; 15; 16] is the main purpose of AR rather than enhancing user engagement. To the best of our knowledge, the effect of an AR animal companion on user engagement in the energy management context has yet to be studied.  
In this study, we aim to investigate the effect of an AR companion on user engagement within the context of an energy management mobile app. We also conduct a perceived usability test to understand how end-users perceive a mobile app with an AR companion. We develop two mobile apps on the PHOENIX platform to serve the energy optimization solution. Each mobile app features a distinct user interface (UI): one incorporates AR, while the other does not. We hypothesized that the UI with an AR companion increases user engagement (\(H_{a}^{1}\)) and perceived usability (\(H_{a}^{2}\)) compared to the UI without AR. We perform user evaluations on both UIs and compare the results to understand the effect of AR companion on user engagement and perceived usability. The following research questions are established for the research aim:  
1. How does an AR companion affect user engagement in the energy management mobile app?
2. How does an AR companion affect perceived usability in the energy management mobile app?  
In Section 2, we described related works about the effects of AR and studies of energy management mobile apps with AR. In Section 3, we present information about the participants of our user evaluation, the system architecture of the PHOENIX solution, the UIs, and the user evaluations. We describe results and discussion about user evaluation data in Section 4 and Section 5, respectively. Section 6 presents the conclusion.