Design of an IOT based Smart Microclimate Monitoring and Controlling System for Naturally Ventilated Polyhouse Cultivation

This research addresses the escalating global food demand by developing an automated, IoT-based microclimate monitoring and control system for sustainable greenhouse cultivation. Traditional agricultural practices often suffer from resource inefficiency and high manual labour intensity, which this study mitigates through a precision agriculture framework implemented within a 292 m² naturally ventilated polyhouse at Precision Farming Development Centre, Tavanur. The system architecture integrates a dual-core ESP32 microcontroller as the primary edge processor, utilizing a DHT22 sensor for high-precision temperature and humidity tracking and a BH1750 sensor for ambient light intensity. Data is synchronized via a 4G LTE gateway to the ThingSpeak IoT platform, providing real-time visualization and remote telemetry. Sensor validation demonstrated high fidelity, with R2 values ranging from 0.965 to 0.985 and a rapid 2-second response time. Environmental results revealed a rhythmic diurnal oscillation where air temperature ascended from a nocturnal minimum of 21°C to a stabilized midday peak of 32.5°C. This thermal profile was inversely correlated with relative humidity, which reached a zenith of 85.5% before dropping to 79% under maximum solar gain. Light intensity served as the primary thermodynamic driver, peaking at 70,000 lux in September. The automated system effectively managed these fluctuations through closed-loop control of actuators, including exhaust fans, supplemental lighting, and solenoid valves for irrigation. This integrated approach provides a scalable, economically viable solution for optimizing greenhouse microclimates and enhancing the productivity of sensitive crops like cucumbers.