Precise quantification of microclimate heterogeneity and canopy group effects in actively heated solar greenhouses

Winter is a critical period for greenhouse crops production. Multi-source sensors were utilized to quantitatively describe the microclimate distribution patterns and the interactions between crops and greenhouse environment during the winter season. By integrating 3D simulation model, we calculated the energy balance of solar greenhouses, thus assessing the suitability and economic efficiency of several common greenhouse heating devices. The results revealed significant discrepancy in energy demand across different planting areas within the greenhouse, especially in the north-south direction. Significant interactions between crops and greenhouse environment were observed. The presence of cucumber canopies significantly increased relative humidity by 3.0% to 3.8% and negatively impacted air temperature by 1.1 ℃ to 2.5 ℃. Considering the energy balance, initial investment in heating devices, usage period, and utilization effectiveness, the light tube radiators were identified as a suitable heating option. Compared to the unheated greenhouse, the heated greenhouse raised minimum temperatures by 5.2 ℃ to 10.2 ℃, reduced maximum relative humidity by 4.2% to 14.6%, and had a return-on-investment period of approximately 4.7 years. These findings offer valuable insights for multi-source sensor deployment, distributed control, structure optimization, and heating design in solar greenhouse.