Microclimate heterogeneity and operational strategies in indoor vertical farm

Microclimate heterogeneity is a major challenge in indoor vertical farms due to multi-layer cultivation and localized heat sources. This study investigates canopy-scale microclimate heterogeneity and evaluates operational strategies using a computational fluid dynamics (CFD) framework incorporating crop transpiration. The model resolves coupled airflow, heat, and moisture transport to capture plant-relevant microclimate conditions. A representative indoor vertical farm was simulated under different combinations of centralized air-conditioning, circulation fans, and water-cooled LED systems. Canopy-scale air temperature, relative humidity, leaf surface temperature, and transpiration were analyzed, and microclimate uniformity was quantified using a uniformity index. The results show that circulation fans are most effective in reducing canopy-scale temperature non-uniformity by enhancing convective heat exchange, while water-cooled LEDs primarily reduce the mean thermal load by mitigating heat release at the source. Canopy-scale analysis further reveals that crop-level microclimate responses are not directly coupled to indoor air humidity conditions. These findings highlight the importance of canopy-scale evaluation and demonstrate that combining localized airflow enhancement with source-level thermal mitigation can achieve uniform thermal environments in indoor vertical farms without major modifications to centralized HVAC systems.