Techniques to maintain optimal temperature inside greenhouse

Maintaining the optimal temperature is crucial for plant growth, flowering, and fruiting in protected horticulture. Temperature management involves cooling in summer and heating in winter depending on the climate and crop requirement.

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 inside.

b. Forced Ventilation

• Use of exhaust fans and blowers to remove excess heat.
• Fans ensure air movement and prevent hotspots.

B. Shading

a. Shade Nets

• Reduces solar radiation and prevents leaf scorching.
• Available in different densities (30–70%) depending on crop and season.

b. Whitewash or Shade Paint

• Applied to greenhouse covering to reflect sunlight and reduce temperature.

C. Evaporative Cooling / Fogging

a. Misting/Fogging Systems

• Fine mist evaporates and cools air around plants.
• Also increases humidity, beneficial in hot, dry regions.

b. Wet Pad Systems

• Air passes through water-soaked pads, lowering greenhouse temperature by evaporation.

D. Thermal Screens and Insulation

a. Thermal Screens

• Retractable screens reduce heat loss during cold nights.
• Helps maintain night temperature and save energy.

b. Insulating Materials

• Polyethylene, double-layer films, or bubble wrap reduce heat loss.
• Important for winter greenhouses in temperate regions.

E. Heating Systems (Winter Management)

a. Hot Water or Steam Pipes: Distributed under benches or along walls for even heating.

b. Electric Heaters: Quick response for small-scale greenhouses.

c. Forced Air Heaters: Distributes warm air efficiently.

d. Soil Heating: Pipes embedded in soil or benches maintain root-zone temperature.

F. Roof and Side Design

a. Gable Roof: Helps natural heat escape; prevents heat accumulation.

b. Orientation: Greenhouse oriented east-west or north-south depending on region maximizes solar efficiency and heat management.

G. Automation and Sensors

a. Temperature Sensors: Monitor inside and outside greenhouse temperature.

b. Automated Vent/Heater Control: Opens vents, starts fans, or switches on heaters based on preset thresholds.

• Ensures consistent optimum temperature with minimal labor.