Greenhouse Climate Automation System

A commercial greenhouse operation was losing crops to humidity fluctuations caused by delayed or missed manual interventions. Staff had to walk the greenhouse rows and manually adjust extractor fans and trigger watering runs based on visual inspection and basic analogue gauges. At night and over weekends, no monitoring happened at all. A single humid night could wipe out a week of growth.

The farm needed a system that could maintain humidity within a defined target band — automatically, around the clock — and alert staff when conditions moved outside the safe range. No off-the-shelf greenhouse controller supported their specific combination of extractor fan types and irrigation solenoid layout.

We designed and deployed a network of custom ESP32 nodes — one per greenhouse zone. Each node reads a DHT22 humidity and temperature sensor and drives its local actuators: a relay-controlled extractor fan for dehumidification and a solenoid valve for the irrigation feed.

The control logic runs entirely on the ESP32 — a configurable hysteresis loop keeps humidity within the target band without oscillation. If humidity rises above the upper threshold, the extractor activates. If it drops below the lower threshold, the irrigation solenoid pulses. The system recovers automatically from power interruptions without any user action.

All telemetry publishes over MQTT to a central broker. A lightweight dashboard gives farm management live readings across all zones, historical trend charts, and SMS alerts when any zone exceeds its configured limits. Firmware is OTA-updatable across the entire node network from a single interface.