Water curtain walls, also known as wet curtain walls, consist of water curtain panels and frames, and are commonly used in negative pressure ventilation and cooling systems. In negative pressure ventilation and cooling systems, a negative pressure fan is used to draw out polluted and hot air from the interior, while the water curtain wall opposite the fan is used for intake. Fresh, hot outdoor air, as it passes through the wet holes of the water curtain wall, undergoes heat exchange with the water, getting filtered and cooled.