A climate-based analysis of photosynthetically active radiation availability in large-scale greenhouses across China

Photosynthetically Active Radiation (PAR) is critically required for sustaining plant and vegetable growth. This study investigated PAR availabilities in two typical large-scale greenhouses using an advanced method of climate-based solar modelling in China. Seven Chinese locations in terms of daylight (solar) climate zones and latitudes were studied. The PAR prediction was conducted via RADIANCE (ray-tracing solar and light simulation package). Key findings were: 1) A climate-based analysis was proved as more practical than the methods based on only clear sky and solar geometries. 2) A ray-tracing solar modelling could effectively predict PAR levels at specific positions (e.g. vertical planes), which could benefit the development of vertical farming activities. 3) The PAR availability could receive insignificant impact from roof configuration in these large-scale greenhouses. 4) For the approach of vertical farming, the vertical arrangement of planting system could be significantly affected by greenhouse orientations, while horizontally no such effect can be found. These findings could be developed into design strategies to support greenhouse planning.

Automated summary

Photosynthetically Active Radiation (PAR) is crucial for plant growth, and a climate-based solar modelling method was found to be more practical in predicting PAR availability. The study showed that ray-tracing solar modelling can effectively predict PAR levels at specific positions, vertical farming activities can benefit from this. Additionally, the roof configuration in large-scale greenhouses has little impact on PAR availability, while the orientation of greenhouse affects the vertical arrangement of planting systems for vertical farming.