greenhouses I shade net I hydroponics I aquaponics
Commercial greenhouse cooling systems: Natural ventilation compared with forced evaporative pad and fan High greenhouse temperatures are extremely detrimental to optimum plant health and growth, which obviously has a negative effect on commercial greenhouse farming yields and profitability. It therefore goes without saying that an effective greenhouse cooling system is one of the most important considerations for greenhouse growers. These solutions are either passive (natural) or forced (mechanical). Forced Ventilation with Evaporative Pad and Fan Cooling Pad and fan he pad and fan cooling system work by using exhaust fans that suck warm air out of the greenhouse creating air flow over evaporative cooling pads. This is a popular method for cooling greenhouses and can reduce tempe ratures significantly (between 5-10 °C
T
6 Undercover farming I
July/August2020
I Volume 17 No 4
depending on the relative humidity) but it has various disadvantages: 1. High energy costs. 2. Higher maintenance costs. 3. Significant temperature variance 4. Mainly effective in dryer climates. 5. Water consumption is higher in pad and fan cooling compared with high pressure fogging.
Natural, Passive Ventilation with High Pressure Fogging Natural ventilation Natural ventilation is the result of
The pad and fan cooling system work by using exhaust fans that suck warm air out of the greenhouse creating air flow over evaporative cooling pads. pressure differences created by the wind and temperature in the inside and outside of a greenhouse. It requires less energy n comparison with pad and fan cooling.
High Pressure Fogging (HPF) If the above-mentioned natural ventilation options are not sufficient 7
