Where should PPV fans be placed for effective ventilation during a high-rise fire?

Placing positive pressure ventilation (PPV) fans at the base of the stairwell and two floors below the fire floor is effective for several reasons. This positioning allows the fans to create a positive pressure zone that helps push smoke and heat upwards and out of the building, thus clearing the smoke from the stairwells and making them safer for evacuation and firefighting operations. By being situated two floors below the fire, the fans can effectively manage the smoke movement and protect the egress routes for both occupants and firefighters.

This strategy minimizes the chance of smoke generating in lower floors during firefighting operations and supports a controlled evacuation by providing clearer paths. It leverages the natural tendency of smoke to rise, thereby improving visibility and air quality for crews engaging with the fire and for residents escaping the building.

Alternative placements, such as at the roof level or in the basement, might not effectively address the immediate smoke conditions on the fire floor or the floors above it. Specifically, placing fans on the fire floor can risk disrupting airflows needed to contain or manage the fire effectively.