Recently, the use of greenhouse is developing. Farming fruits and vegetables using a greenhouse can overcome the unpredictable climate. The plants that need specific air temperature and humidity could grow well inside a greenhouse. As a preliminary study, the effect of circulating water as a thin film at the outer surface of the greenhouse is observed. The water film is intended to cool the greenhouse. In this experiment, there are three models used. The first isthe greenhouse (called GH1) with cooling water flowing at the outer surface of greenhouse periodically. The second is a greenhouse (called GH2) without a cooling system and the third is in the open space or natural farming. A water sprayer is installed in each model to water the plants. It sprays periodically. In each greenhouse, three temperature and humidity loggers are installed to measure the air temperature and humidity. The loggers are installed in the middle of the greenhouses with some different heights from the plants. From the experimental results, the air temperature in the greenhouse GH1 decreased compared to the ambient temperature at position 3, while at GH 2 and open space farm N thetemperature increased at positions 1, 2, and 3. The average relative humidity was 72%, 68 %, and 47% at GH 1, GH 2, and open space farm (N).
