Design and Implementation of an Internet of Things System for Air Conditioner Monitoring and Control

Abstract

An Air Conditioner (AC) is widely used to keep indoor spaces comfortable, but its operation is commonly managed manually through a remote control, which often leads to operational negligence such as forgetting to switch off the unit when a room is empty. This negligence results in energy waste and increased electricity costs, a problem that is particularly relevant for spaces with high-intensity, scheduled usage such as houses of worship. This study aims to design and build an Internet of Things (IoT) system for automatic and remote monitoring and control of an AC unit, using the Kibaid Church congregation in Samarinda as a case study. The system is built around an ESP32 microcontroller integrated with a DHT22 sensor for temperature and humidity monitoring, a PZEM-004T module for real-time power-consumption monitoring, a rain-drop sensor for water-leak detection, and a Solid State Relay (SSR) for switching the AC unit on or off, with a local 16x4 LCD display and the Blynk mobile application for remote monitoring, manual control, and push notifications. The DHT22 temperature sensor was first calibrated against the AC thermostat setpoint, and functional testing was then carried out on nine core features in a controlled pre-testing environment prior to on-site deployment. The calibration results show an average temperature deviation of only 0.17 degrees Celsius, and all nine functional test scenarios—covering sensor readings, leak detection, local display, cloud data transmission, automatic and manual AC control, high-temperature notification, and a 24-hour endurance run—were completed successfully. These findings indicate that the developed system can reliably automate AC operation, provide real-time remote monitoring, and help reduce energy waste caused by operational negligence.