Which mechanical ventilation method employs large fans to force air into a structure?

Positive-pressure ventilation is the method that uses large fans to force air into a structure. This technique is employed to quickly clear smoke, heat, and toxic gases during firefighting operations or in other emergency situations. By introducing a high volume of fresh air into the building, positive-pressure ventilation creates a pressure differential that drives the smoke and heat out of designated openings, enhancing visibility and providing a safer environment for both firefighters and victims.

In contrast, hydraulic ventilation utilizes a stream of water to create airflow, natural ventilation relies on environmental factors such as wind and temperature differences to create air movement, and negative-pressure ventilation involves the use of fans to exhaust air from a structure, creating a vacuum effect that can draw in outside air through openings. Each of these methods has distinct applications and is suited for different scenarios in firefighting operations, but positive-pressure ventilation specifically focuses on actively introducing air into the space to aid in smoke removal and improve conditions inside the building.