Two experimental greenhouses were used in this study, (G1) a greenhouse was ventilated naturally (as control) and (G2) another greenhouse was cooled by using solar energy, it contains: principally of the units: regeneration heat source (solar collector), the rotary wheel dehumidifier (The first part was the regeneration part that equals 50% of the total surface area).   Two pad materials were used as pads for cooling, the used materials were cellulose and palm fiber. Three different air velocities of 1,2and 3 m/s were used with each pad material. Three water flow rats of 10, 15 and 20 L/min were used on each pad. The experiments were carried out in the premises of an open roof (third floor) of a Faculty of Agriculture Engineering, Al- Azhar University, Nasr City, Cairo Egypt (Latitude angle of 30° 02' 30" N, Longitude angle of 31° 14' 07" E, and mean altitude above sea level of 18 m). The experiments were carried out on April to July2018. The obtained results indicated that the average temperature of 31.0 °C was outside the greenhouse through all the experiments while the average temperatures of 36.4, 24.5 °C were inside the greenhouses (G1), (G2), respectively. The average temperature reduction of 6.6 °C was outside and inside the cooling greenhouse by using solar energy, while the average temperature reduction of 11.9 °C was in the un cooled greenhouse. The highest cooling efficiency of 79.5% was recorded   when the outside temperature of 30.6 °C and relative humidity of 41.2%, the previous  highest cooling efficiency was when the cellulose pad material was used at water flow rate of 20L/min and wheal face air velocity of 2 m/s.