NCC PART F – NATURAL VENTILATION

Effective Natural Ventilation Starts With Good Design

Meeting the NCC's natural ventilation opening-area requirements is only the starting point. The 5% rule doesn't guarantee ventilation – it often guarantees excess cost. Airocle helps engineers, architects and builders design strategically positioned ventilation openings that optimise airflow, heat removal and building performance.

Explore NCC Part E2 Smoke Hazard Management

Meeting the NCC's natural ventilation opening-area requirements is only the starting point. The 5% rule doesn't guarantee ventilation – it often guarantees excess cost. Airocle helps engineers, architects and builders design strategically positioned ventilation openings that optimise airflow, heat removal and building performance.

Explore NCC Part E2 Smoke Hazard Management

QTMP Torbanlea

The Challenge: Opening Area Alone Doesn't Guarantee Effective Ventilation

The NCC's 5% Deemed-to-Satisfy (DtS) opening-area provision establishes a prescriptive pathway for natural ventilation in applicable spaces. For a 10,000 m² space, this can mean providing 500 m² of ventilation openings.

However, meeting this requirement doesn't necessarily mean air will move effectively throughout the building.

Poorly positioned openings can restrict airflow, create stagnant areas and allow heat to accumulate at roof level. It's not simply how much opening area a building has, but where those openings are positioned and how air moves between them.

Where the 5% opening-area requirement is impractical, costly or unsuitable, an NCC Part F Performance Solution may provide an alternative compliance pathway. Through engineering assessment, a more strategically designed ventilation system may achieve better airflow performance with fewer openings, subject to demonstrating compliance with the relevant NCC Performance Requirements.

Explore NCC Part F Performance Solution

Meeting the 5% DTS Requirement Doesn't Guarantee Effective Ventilation

POOR AIRFLOW DESIGN

DTS Poorly Positioned

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.

EFFECTIVE AIRFLOW DESIGN

Strategically Designed Ventilation Openings

Well-positioned low-level air inlets and high-level roof ventilators encourage crossflow and stack-driven ventilation. This helps fresh air move through the building while allowing accumulated warm air to escape, improving overall ventilation effectiveness.

Assess Building Requirements

We evaluate building geometry, internal heat loads, operational conditions and applicable NCC provisions to identify ventilation requirements and potential airflow challenge

Design & Optimise Airflow

Our engineers determine suitable inlet and exhaust locations, considering wind pressure, thermal buoyancy and airflow distribution. Where appropriate, CFD modelling helps evaluate and refine the proposed ventilation design.

Specify & Deliver

We translate the engineering design into practical ventilation solutions, selecting appropriate products and supporting integration with the building. Airocle can manufacture, supply and install the specified systems.

NATURAL AIRFLOW IN ACTION

Prevailing winds to move air through a building.

Wind Pressure

Consider five standard roller doors open on the windward face of an industrial building, providing approximately 25 m² of inlet area, together with ridge-mounted natural ventilators.

At a moderate wind speed of 4 m/s, this configuration can generate approximately 40–50 m³/s of airflow through the building.

That's equivalent to the airflow of approximately 20 × 500 mm axial fans running at full speed, based on the engineers' illustrative comparison.

Rising warm air to create natural airflow.

Thermal Bouyancy

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.

NCC Part F – Natural Ventilation

Strategically positioned low-level air inlets and high-level roof ventilators encourage natural airflow through the building, supporting fresh air movement and the removal of accumulated heat for everyday ventilation.

Part E2 – Smoke Hazard Management

The same roof-mounted ventilation infrastructure can form part of a natural smoke exhaust strategy, allowing hot smoke to escape through appropriately designed roof ventilators while low-level openings provide make-up air.

Explore Performance Solutions Beyond the 5% DTS Requirement

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READY TO OPTIMISE YOUR BUILDING'S VENTILATION?

Speak With Our Design Team Today

Whether you need assistance complying with NCC Part F, E2 requirements or custom performance solution for your project, our design team is here to assist.

Effective Natural Ventilation Starts With Good Design