Optimum design of Chinese solar greenhouses for maximum energy availability

Given the aging of greenhouse facility, there is a need for investigating the transformation of existing greenhouses to maximize solar energy utilization. In this study, Chinese solar greenhouse (CSG) in the Beijing area served as an optimized prototype. A mathematical model was established to determine the range of CSG vertex positions. Then, a 3D dynamic simulation model was developed to optimize greenhouse structure and determine the lighting roof shape that offers better light and temperature environments. The structural safety of CSG steel skeletons was assessed and designed using finite element software. The optimized greenhouse significantly improved the indoor climate, particularly in light environment. Compared to the original greenhouse, the average captured solar energy of the optimized CSG increased by 5.4 MJ m- 2, and the average temperature increased by 3.1 degrees C. The maximum differences in solar radiation and temperature among various lighting roof shapes are 4.8 % and 6.1 %, respectively. Furthermore, the optimized CSG steel skeletons met the requirements for structural stability. The payback period of CSG optimization was about 1.6 years. These methods and findings provide valuable design strategies for upgrading old greenhouses and can be further applied in different regions.