Thermal Bouyancy (solution)

Natural smoke ventilation uses the buoyancy of hot smoke to support its movement towards high-level exhaust openings. At the same time, appropriately positioned low-level inlets allow replacement air to enter the building.

The relationship between exhaust capacity and make-up air is critical. Insufficient replacement air can restrict smoke exhaust performance, while poorly positioned or excessive inlet airflow can disturb the smoke layer and influence smoke movement.

Airocle considers opening locations, aerodynamic performance, smoke exhaust capacity and make-up air provision as part of an engineered system designed to support the building's fire safety strategy and applicable NCC Part E2 requirements.

When internal temperatures exceed outdoor conditions, warm air rises towards high-level roof openings, drawing cooler outdoor air through lower-level inlets.

In a building operating at 10°C above ambient temperature, with a 9 m floor-to-ridge height differential, stack effect alone can generate approximately 15–20 m³/s of airflow.

That's equivalent to approximately 6 × 500 mm axial fans running at full speed, based on the engineers' illustrative comparison.

Both examples demonstrate how effective opening placement can make use of naturally occurring airflow forces to ventilate industrial spaces.

A Performance Solution allows an alternative ventilation design to be assessed against the relevant NCC Performance Requirements, rather than relying solely on the prescribed opening-area provisions.

Through engineering calculations, airflow assessment and, where appropriate, CFD modelling, strategically positioned ventilation openings may achieve the required performance with less opening area, subject to appropriate compliance verification.