Ceiling ventilation fans act as the "balancing valve" for maintaining uniform temperature and humidity in fresh-keeping storage, directly impacting the quality of stored fruits and vegetables. Many fresh-keeping storage facilities suffer from inadequate ventilation systems, where ceiling fans are not installed as required. While this may seem like a way to save on equipment costs, it often results in localized humidity buildup, creating a dilemma where leafy greens are simultaneously exposed to freezing and mold growth, severely compromising storage efficiency. Leafy greens thrive in a storage humidity range of 85%-95%, but this requires even distribution through proper air circulation. Without ceiling ventilation fans, the cold air blown by evaporators tends to accumulate in lower areas, creating a cold zone. Meanwhile, stagnant air in the upper areas traps moisture, resulting in an imbalanced environment characterized by "high humidity above and low temperature below." In the lower cold zone, temperatures can drop below 0°C, causing the cellular structure of leafy greens to freeze and sustain frost damage. In the upper high-humidity zone, moisture condenses on the surface of the leaves, creating ideal conditions for mold growth and leading to decay. The absence of a ventilation system further increases the risk of spoilage. Localized high-humidity conditions accelerate the respiration of leafy greens, causing them to wilt and yellow prematurely and shortening their storage life. Frost-damaged leaves are more susceptible to bacterial contamination, which can spread to nearby healthy vegetables, causing a chain reaction of spoilage. In contrast, ceiling ventilation fans ensure forced air circulation, keeping temperature fluctuations within ±0.5°C and maintaining even humidity distribution. This prevents localized high-humidity or low-temperature zones. The ventilation system in fresh-keeping storage must be scientifically configured:

· Install one ceiling ventilation fan per 10 m², with a power rating of at least 30W, and ensure the air outlets are evenly distributed to cover all areas without dead zones.

· Synchronize the fans with the refrigeration system so they start and stop in tandem with the evaporators, enabling coordinated temperature and humidity control.

· Regularly clean the fan filters to prevent dust buildup, which can impede airflow and reduce ventilation efficiency.

        The essence of fresh-keeping storage is "maintaining both constant temperature and constant humidity," making ceiling ventilation fans essential rather than optional. While upfront investment in a ventilation system may seem costly, it significantly reduces leafy green spoilage rates—from over 20% to less than 5%—by maintaining a stable and uniform environment. Emphasizing proper ventilation ensures that fresh-keeping storage truly delivers on its promise of "preservation."