PREDICTION OF THE EFFECT OF INSECT-PROOF SCREENS ON CLIMATE IN A NATURALLY VENTILATED GREENHOUSE IN HUMID TROPICAL CLIMATES

The impact of different types of insect-proof screens on greenhouse climate in humid tropics needs to be quantified in order to develop technically and economically optimal greenhouse constructions. Thus, physical properties of various insect-proof screens were determined in the laboratory at the Institute of Horticultural and Agricultural Engineering, University of Hannover, Germany. Specially adapted experimental greenhouses were built at AIT campus in Bangkok, Thailand. A dynamic energy and mass balance model of the greenhouse system was developed to predict the greenhouse climate from external weather data and properties of insect screens. Scenario simulations were carried out to predict the effect of screen properties on greenhouse climate. External and greenhouse climate measurements were made in Bangkok. The internal climate measurements were carried out concurrently in two similar, naturally-ventilated greenhouses covered with different insect-proof screens on ventilation openings. Tomato (Lycopersicon esculentum ‘King Kong II’) plants were grown in the greenhouse during the experimental period. Model predictions of greenhouse air temperature were compared to measurements from the two greenhouses and good agreement was achieved. The results form a good basis for decisions on screened greenhouse design improvements and climate control interventions in screened greenhouses in the humid tropical climates.