A Gable even span greenhouse 3 × 2 × 2.6 m was constructed. This greenhouse was equipped with an evaporative cooling system. Three waste materials were used as pads for this system. These materials are: Flax plant residues, Luffa plant residues and the third material was a combination of the two materials. Each pad material was tested under three thicknesses. These thicknesses are 4, 8 and 12 cm. Each thickness for each of the three materials was tested under three velocities. These velocities are 0.45, 0.65 and 0.90 m/s. The experiments were carried out during august 2008 where the mean ambient temperature was 35.8 oC and the mean relative humidity was 39.6 %. Mean cool temperatures at the pads were 25.5, 25.9 and 26.6 oC for Flax plant residues, Luffa Plan residues and the combined material respectively. Highest cooling efficiency was 97.7 % when using Flax plant residues pad material with thickness 12 cm at pad face air velocity 0.65 m/s. For Luffa material the highest cooling efficiency was 91% at used pad thickness 12 cm and pad face air velocity 0.45 m/s. For the Combined material the highest cooling efficiency was 94.4 % at used pad thickness 12 cm and pad face air velocity 0.45 m/s. The research concluded to that the recommended pad is Flax and the recommended thickness for the system is 12 cm and the recommended pad face velocity is 0.45 m/s. The correcting Length factor “K” for the greenhouses of length “L” where: was determined roughly by the eye carve fitting.