Real-Time Indoor Thermal Comfort Monitoring and Analysis Using IoT Sensors

This paper presents the design and development of a low-cost, real-time indoor thermal comfort monitoring system built using IoT sensors and an ESP32 microcontroller. The system integrates DHT22, DS18B20, and MQ-135 sensors connected to an ESP32 board and linked wirelessly to the ThingSpeak cloud platform. Data was collected over six months (July to December 2024) in a Gurugram classroom, yielding over 50,000 data points per sensor. Analysis against ASHRAE Standard 55-2020 comfort thresholds shows that the monitored space remained outside the comfort zone for approximately 77% of the observation period. The prototype achieved 97.3% data transmission success and 98.6% uptime at a total hardware cost of approximately INR 1,350.