In order to push forward the utilization of a greenhouse even in summer, it is necessary to prevent the rise in temperature inside of it.
1) The natural ventilation, in which the ventilation space was equal to 20-30% of the floor area of the floor area of a plastic house (5.5m×8.6m), was equivalent to the forced ventilatilation of 3-4m3/min./m2 of the floor area.
2) The combination of the natural and the forced ventilation contributed to reduce a difference in temperature between inside and outside of the plastic house.
3) When the plastic house was covered with a double layer of black cheesecloth (#600) for shading, the natural ventilation of 30% of window open ratio (O/F) and the forced ventilation by three fans resulted in the effective prevention of the rise in temperature inside of it.
4) By applying an evaporative cooling system (the mist and fan type), spreading the area of a screentype eliminator and shading with the cheesecloth, we were able to cool the inside temperature and also to reduce a gradient in temperature along the direction of airstream in the plastic house.
