Misting is a basic and low cost system used to cool and humidify the greenhouse environment.

Misting signifies lower pressure and conversely larger water droplets, which are typically around 200 microns. In this case, flash evaporation does not occur as quickly as high pressure fogging, but instead drops to the floor resulting in in some wetness on surfaces. However, misting can be a great option when minor wetting of the plant and foliage is permitted.

When wetting of the plant cannot be tolerated to any extent – for example if health and safety issues arise or if disease is apparent – one must consider high pressure fogging, which typically has a droplet size of around 10 microns – see the high pressure fog section for more details.

“The combination of ventilation with shade screening and low-pressure fogging above the ‘shade’ screen yielded inside temperature reductions close to those achieved by low-pressure fogging under the screen, but did not produce high humidity levels around the plant” – A Perdigones, L Garcia, A Romero, A Rodriguez, L Luna, C Raposo, S de la Plaza

Department of Rural Engineering, Uniuersidad Politecnica de Madrid, Spain