Air curtains are devices installed over entrances or openings to create a barrier of controlled air flow. They typically discharge a stream of air either horizontally or vertically, serving as an invisible barrier that helps prevent the exchange of outdoor and indoor air, thus minimizing temperature loss and preventing the entry of dust, insects, or pollutants. Commonly used in commercial and industrial settings, air curtains are energy-efficient solutions for maintaining comfortable indoor environments while improving energy conservation by reducing the need for heating or cooling.