Technically, three methods are used for cooling and reducing greenhouse temperatures:

Air exchange between the air inside the greenhouse and the outside atmosphere.
This exchange is accomplished either passively through roof and side vents, or actively by operating ventilators that increase the rate of air exchange when natural air exchange is insufficient for the plant’s requirements.

Adiabatic cooling, which increases the humidity while lowering the temperature inside the greenhouse. Coolnet foggers or wet pads are used for this process.
Wet Pad
The wet pad system includes:

  • Wet pad
  • Fans
  • Pipe for water dispersion over the wet pad
  • Submerged pump
  • Water tank
  • Pipe system for water supply

Reducing radiation penetration uses stationary or movable shade screens. Radiation causes the greenhouse space to heat up (the greenhouse effect). By reducing the intensity of radiation penetration, the heat inside the greenhouse is decreased. Radiation reduction also cuts down light penetration, essential to the plant’s photosynthesis process. This conflict can be optimized by using moveable screens operated automatically or manually, and/or screens with relatively low shading percentages.

The shading rate can be adjusted to between 20% and 80% depending on climatic conditions and type of crop. House plants, for example, will have relatively high shading levels in comparison with vegetables.

The most common shade screens are black. However, it was recently found that by Colorshadenets, which change the light spectrum while retaining the same level of shading, can reduce radiation penetration and influence morphological changes in a large range of plant varieties.