Public institutions often face challenges in managing energy efficiently across distributed facilities with limited technical personnel. Manual control of lighting and environmental conditions contributes to unnecessary energy consumption, especially outside regular operating hours. Emerging IoT platforms offer accessible alternatives for automation without the need for complex infrastructure. Integrating mobile applications with microcontroller-based systems can support real-time monitoring and control, reducing waste and simplifying operational routines. This project explores the development of an IoT-based energy management system enabling remote device control through applications that are compatible with Android and iOS. The architecture is based on ESP32 microcontrollers integrated with temperature and humidity sensors (DHT11), LEDs, and relays. Three platforms were tested: MQTT Dashboard, ESP RainMaker, and a custom mobile app developed using MIT App Inventor. MQTT was used for data transmission and command handling via public brokers. The mobile app allowed for profile selection, room identification, sensor data visualization, and lighting control. MQTT Dashboard provided a stable interface for real-time communication, while ESP RainMaker added automation features such as scheduled routines. All approaches demonstrated consistent functionality, with MIT App Inventor standing out for its ease of use and educational value. The system supports scalability, enabling expansion to other rooms and buildings. These results confirm the feasibility of implementing remote energy control through open technologies, offering a practical solution for improving efficiency and simplifying maintenance routines in public educational institutions.