Articles
OPTIMIZATION OF NOCTURNAL CLIMATE MANAGEMENT IN PE-GREENHOUSES IN CYPRUS
Article number
691_100
Pages
815 – 820
Language
English
Abstract
This work deals with the automatic control of humidity in heated polyethylene (PE) covered greenhouses during the night under the Mediterranean weather conditions of Cyprus.
Besides temperature, the most important limiting factor under Cyprus conditions is the relative humidity, especially during winter nights.
High relative humidity leads to the development of fungal diseases, such as mildew, botrytis, late blight, etc.
The experiments were carried out during winter 2003 and spring 2004 aiming to improve the control system previously developed at ARI. Relative humidity control was accomplished by combining forced ventilation and air movement in the greenhouse and by adjusting the heater-temperature between certain minimum and maximum limits.
The amount of introduced fresh air varied and the exhaust cycle was performed every 20 or 30 minutes according to the temperature and humidity conditions inside and outside the greenhouse.
This became possible by using a programmable controller.
The results showed that the combined 20/30-minute cycle is preferable, in comparison to the 20-minute cycle, if keeping the relative humidity in the greenhouse between 70 and 85% will be satisfied for most of the time in winter at a lower cost.
Besides temperature, the most important limiting factor under Cyprus conditions is the relative humidity, especially during winter nights.
High relative humidity leads to the development of fungal diseases, such as mildew, botrytis, late blight, etc.
The experiments were carried out during winter 2003 and spring 2004 aiming to improve the control system previously developed at ARI. Relative humidity control was accomplished by combining forced ventilation and air movement in the greenhouse and by adjusting the heater-temperature between certain minimum and maximum limits.
The amount of introduced fresh air varied and the exhaust cycle was performed every 20 or 30 minutes according to the temperature and humidity conditions inside and outside the greenhouse.
This became possible by using a programmable controller.
The results showed that the combined 20/30-minute cycle is preferable, in comparison to the 20-minute cycle, if keeping the relative humidity in the greenhouse between 70 and 85% will be satisfied for most of the time in winter at a lower cost.
Authors
P. Polycarpou
Keywords
greenhouses, environmental control, humidity control, forced ventilation
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