Simulation and Analysis of Direct Solar Radiation in Greenhouses in Beijing Area——The Fourth Part of Serial Studies on Simulation of Light Environment of Farming under Structure

Solar greenhouses are prevailing agricultural installations in China at the present time, but their shapes differ greatly in different areas. Because little research has been conducted on the changes of light environment with greenhouse shapes, no enough information has been given to estimate which kind of greenhouse shape is better. In this paper, on the basis of previous studies, the authors simulated several typical solar greenhouses in Beijing area according to the characteristics of daily light integral and light distribution. The simulating results show that the shape of greenhouse greatly affects the light environment of greenhouse, not only in daily integral but also in distribution. Take an example, the maximum difference of daily light integral among those greenhouses reaches 41. 4%, but on the part of ground level, only 6. 7%. Therefore, both light integral and light distribution are factors of the same imporfance when trying to estimate and optimize the greenhouse shape. The results also provide a scientific reference to funher improve the shape or structure of the solar greenhouses in Beijing area as well as in other areas in China.