Environmental control of greenhouse and plastic cover. I

Climatic measurements in the cooling greenhouse with ornamental crops

Abstract

1. Climatic factors were measured in large gutter-connected greenhouses which are equipped with the cooling system as pad-and fan in Kusatsu City of Shiga Prefecture.
2. The greenhouses measured were so different from one another in their structures, aeration systems and crops, that the temperature and wind velocity were studied for three to four successive sunny days during August 4 to 17, 1965.
3. When the direction of ventilation crossed in the greenhouse with a continuous roof, the results were as follows. The temperature was maximum at the point just under the ridge of the roof, and minimum under the furrow. On the contrary, the velocity of wind was maximum at the point under the furrow and minimum under the ridge. The temperature of ventilated wind increased as it flowed from the pad side to the fan side, and it reached the outdoor temperature just before the wind went out.
4. The increase in temperature was linear in the greenhouse in which the ventilation system ran parallel with the ridge. The increasing rate of temperature in this type of greenhouse was more remarkable than that in the crossed type.
5. The cooling effect on carnation planted in beds was more distinct than on carnation planted in benches or rose planted in beds. The temperature increased most in the greenhouse which had vigorous roses of tall height in it.
6. Two things must be considered about the cooling effect of greenhouse, namely the heat exchange of water and the cooling effect by evaporation. The heat exchange of water is constant when the temperature and the amount of water are constant, while cooling by evaporation is variable depending upon the direction of ventilation capactity of fan and some factors of weather.