Greenhouses require energy in order to provide a proper environment for crop production. Utilizing solar energy in solar greenhouses is a sustainable solution to face this problem. In this study, a solar greenhouse concept is considered, and a dynamic thermal model is developed to predict the inside air temperature. The model is integrated into an optimization procedure to find the optimal greenhouse design that has the best thermal performance by adjusting its structural parameters. This optimization procedure provides a tool to find the optimal solar greenhouse design for each climate condition and predict its performance. For instance, for the case study of Tehran (Iran), the optimal solar greenhouse works 85% of times passively in a year. Besides, this tool is flexible to change the objective function, from year-round performance to seasonal or cultivation period performances. For example, the optimal solar greenhouse for the case study has completely different structural parameters comparing the optimal seasonal solar greenhouse. This is also a decision-making tool to decide the cultivation type based on best energy performance. For the case study, the results indicate that the cultivation of cucumber, melon, and watermelon is the priority comparing other usual greenhouse products. (C) 2019 Elsevier Ltd. All rights reserved.