To promote energy-saving behavior, disaggregating electricity usage is critical for increasing consumer awareness of energy usage behavior. This study proposes HeatProbe, a thermal-based power meter system that uses thermal imaging to track disaggregated appliance usage. We have designed, prototyped, and tested the HeatProbe system. Results show that HeatProbe successfully senses individual appliance operating durations with an average error of 125.03 seconds, achieving 80.2% appliance power accounting accuracy in different appliance usage scenarios. Author Keywords Power Consumption Monitoring, Per-appliance Power Disaggregation. ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. General Terms Design, Experimentation.