When Smoke Cannot Escape Effectively

Engineering calculations help assess how wind pressure, thermal buoyancy and building geometry influence natural ventilation performance.

By evaluating inlet and outlet areas, pressure differences and anticipated operating conditions, engineers can estimate airflow rates and assess alternative ventilation configurations.

These calculations provide supporting evidence for a proposed Performance Solution, helping determine whether the design can meet the project's agreed ventilation performance criteria.

During a fire, hot smoke rises and accumulates beneath the roof, forming a smoke layer that can spread throughout the building.

Without effective smoke exhaust, this layer can deepen, reducing visibility, increasing heat exposure and creating hazardous conditions for occupants and emergency responders.

Building geometry, smoke movement and the availability of suitable exhaust paths all influence how quickly conditions deteriorate

Meeting the NCC's 5% Deemed-to-Satisfy (DTS) opening-area requirement doesn't automatically ensure effective ventilation. Poorly positioned openings can restrict airflow, trap heat at roof level and leave parts of the building with inadequate air movement.