Two similar experimental poly-greenhouses were used in this study. The first one was covered by double layers of polyethylene with 8-cm air gap and the second one was covered by double layers of polyethylene stick to each other. The experiments were carried out to study the effect of using double layers of polyethylene with air gap on the energy transport characteristics and most relative vegetative growth parameters and production of a tomato crop under Fayoum depression climatic conditions (Egypt). Hybrid variety (ALZAIN F1, seeds) of tomato seeds were germinated under poly-greenhouses and one-month-old seedlings (120-mm length and six leaves approximately) were transplanted in both poly-greenhouses. The obtained results indicated that using 63% shading cover for both greenhouses (in summer months) resulted in reduction of solar radiation by 69.2% and 72.4 % inside the first greenhouse (G1) and the second greenhouse (G2), respectively. The greatest value of cooling effect (11.86 °C) and effectiveness of evaporative cooling system (73.85%) were achieved inside the first greenhouse (G1), which covered by double layers of polyethylene with 8-cm air gap, whereas, the cooling effect (9.19 oC) and effectiveness of cooling system (67.57 %) occurred inside the second greenhouse (G2), which covered by double layer of polyethylene without air gap. The first Greenhouse (G1) increased the temperature of cold air just leaving the cooling system by 3.86 °C, while the second greenhouse (G2) increased the interior ambient air temperature by 5.46 °C. Thus, the first greenhouse (G1), on the average, increased the rate of vegetative growth by 11.5%, and fresh yield of tomato crop by 34.39% comparing with the second greenhouse (G2).