This study presents a model development to determine the optimum orientation of a greenhouse for year round applications under different climatic conditions. The most commonly structural form used in the study is gable-even-span single type greenhouse with different orientations. Total solar radiation flux incident on each wall, included vertical surfaces and inclined roofs, was computed for solar greenhouse orientations and compared for January and July months of the year at the northern hemisphere. Model validation was executed for the measured global solar radiation data on a horizontal surface at the Faculty of Agriculture, Toukh, Qalubia, Egypt (30.36°N, 31.22°E and altitude 15m,. The obtained results showed that, the predicted and measured values are in close agreement. Results also revealed that, the orientation of east-west (E) and south-north (S) of gable even-span solar greenhouse, respectively, was the best suited during January and July months.