Conclusions

GUIs are ubiquitous on handheld computers. In this work, we presented the first study to characterize the energy consumption of GUIs implemented on three different GUI platforms. We analyzed the GUI energy consumption from the hardware, software and application perspectives. Although our characterization is not exhaustive, our methodology can be used for more comprehensive studies. We demonstrated that a GUI consumes a significant amount of energy and showed that there are a number of ways to make it more energy-efficient and energy-aware. This provides a solid foundation for further research on energy-aware and energy-efficient GUI and GUI platform design. When multiple windows are displayed on the screen simultaneously and used in turn, it is important to update the screen so that the appropriate window is active. This task is called window management. On handheld computers, it is rare to use multiple windows due to the limited screen size. Thus, window management is not important for such computers and, therefore, we did not address it in this study. However, for systems with larger screens, such as notebook computers, window management will be important for a GUI's energy efficiency since it determines how the screen is updated when the user focus changes.