Study on the Effect of Non-Uniform Ventilation on Energy and Plant Growth in a Greenhouse

The progress of local environmental regulation in protected agriculture is sluggish, particularly concerning the local air supply, which poses a significant obstacle to greenhouse energy-saving research. This study establishes a test platform for local air supply in winter and summer by integrating design principles from human settlements’ supply air bag models with crop growth requirements. By utilizing a supply air bag to direct fresh air from the air conditioning system to specific areas within the greenhouse, non-uniform ventilation is created. Research has revealed that varying air supply levels in summer exerts a significant influence on environmental conditions, crop growth, and energy efficiency. Noticeable temperature stratification and cooling effects were observed within the conditioning greenhouse. The growth of lettuce was moderately enhanced, with mid-level local air supply demonstrating superior cooling effectiveness and range compared to the other two levels. Optimal control efficacy and energy conservation were achieved through mid-level local air supply. During daytime experiments in winter, this system did not have a significant impact on the greenhouse environment; however, during nighttime experiments, it consistently provided warming effects to maintain temperatures above the minimum requirement for lettuce growth. Therefore, utilizing air supply bags at secure specific positions and implementing targeted air supply methods within cultivation areas in greenhouses can facilitate the creation of suitable local environments for crop growth while achieving energy savings. Future research in this field could focus on further refining air supply bag models to enhance energy efficiency and local environmental control effects.