Greenhouse cooling techniques

Maintaining optimal temperature is critical for plant growth, flowering, and fruiting. Cooling is especially necessary in hot and semi-arid regions to prevent heat stress.

A. Ventilation

a. Natural Ventilation

• Roof and side vents allow hot air to escape and fresh air to enter.
• Cross-ventilation ensures uniform temperature and humidity.

b. Forced Ventilation

• Use of exhaust fans to remove excess heat.
• Fans maintain air movement and prevent hot air pockets.

B. Shading

a. Shade Nets

• Reduce solar radiation by 30–70% depending on crop requirements.
• Protects plants from leaf scorching and overheating.

b. Whitewash / Shade Paint: Applied on greenhouse covering to reflect sunlight and lower temperature.

C. Evaporative Cooling

a. Misting or Fogging Systems: Fine mist evaporates around plants, reducing air temperature and increasing humidity.

b. Wet Pad System (Pad and Fan Cooling)

• Air passes through water-soaked pads; evaporation cools incoming air.
• Common in commercial greenhouses in hot climates.

D. Thermal Screens

• Retractable screens or blackout curtains reduce heat gain during daytime.
• Can also retain cooler air in shaded sections of the greenhouse.

E. Roof and Side Design

a. High Roof & Sloped Roof: Promotes hot air escape naturally.

b. Proper Orientation: Aligning greenhouse to optimize airflow can enhance passive cooling.

F. Automation and Sensors

• Temperature Sensors detect excessive heat.
• Automated Vent or Fan Control ensures timely cooling without human intervention.