How do open display cases maintain temperature without doors?

Open display cases maintain temperature without doors primarily by utilizing a curtain of cold air. This system creates a barrier that separates the chilled products from the warmer air in the store. When cold air is continually circulated, it helps keep the temperature of the displayed items low, minimizing the impact of the ambient temperature of the retail environment. This method is effective in maintaining freshness while also allowing easy access for customers, which is a significant advantage in a retail setting.

Other options do not accurately represent how open display cases function. While solid walls might contain cold air, open cases specifically rely on air movement and the creation of a cold air curtain, making this option less relevant. Continuously replacing products may maintain freshness but does not affect temperature retention. Lastly, built-in heating elements are not applicable in a system designed to keep products cool, as they would contradict the primary purpose of these display cases.