What Every Designer Should Know About Airflow

What Every Designer Should Know About Airflow

Airflow is often treated as someone else’s responsibility, the mechanical engineer’s problem to solve later. But by the time it comes up, you’re already deep in documentation, and design flexibility is gone.

Here’s the reality: airflow isn’t just about heating or cooling. It affects how people feel in a space, how productive they are, whether your building meets compliance and how much it costs to operate for the next 25 years.

When airflow is designed well from the start, it improves comfort, supports health and safety, and reduces the risk of expensive retrofits later. When it’s neglected, it can lead to stagnant air, uneven temperatures, heat stress, and ongoing maintenance issues.

In this article, you’ll get a clear, designer-focused overview of how airflow works, why it matters, and what natural ventilation systems are available, so you can make informed decisions, early.

Why Airflow Matters 

Airflow is often underestimated. It’s not just about cooling or heating, it’s about how air moves through a space and how that impacts the people inside it. 

When airflow is designed well, it improves comfort, reduces fatigue, supports focus, and maintains indoor health. When it’s neglected, it can lead to stagnant air, uneven temperatures, and even WHS issues. 

Comfort and Productivity Go Hand-in-Hand

Thermal comfort has a direct impact on how people perform. Poorly ventilated environments can lead to reduced concentration, slower reaction times, and increased sick leave, symptoms commonly linked to Sick Building Syndrome (SBS).

Under the Work Health and Safety Act 2011, employers have a duty to provide effective ventilation to protect indoor air quality and employee wellbeing. There’s also a measurable link between comfort and productivity. The Thermal Work Limit (TWL) defines the maximum safe metabolic rate a person can sustain in a given thermal environment, making it a key benchmark in settings where physical performance matters. 

From warehouses and schools to hospitals and offices, thermal comfort isn’t a nice-to-have, it’s a performance requirement. 

Key Factors in Thermal Comfort (from an Airflow Perspective) 

When people think about thermal comfort, temperature is usually the first thing that comes to mind. But airflow plays a major role and it’s often overlooked. From a design perspective, the three critical factors to consider are humidity, air velocity, and air temperature. 

These directly affect whether a space feels comfortable, supports productivity, and meets safety expectations. 

Humidity 

High humidity makes spaces feel hotter than they are, especially when airflow isn’t removing moisture effectively. Without proper ventilation, rooms can feel sticky and uncomfortable, even if the thermostat reads fine. 

Low humidity can also cause issues, leading to dryness, irritation, and discomfort. This is especially noticeable in sealed or mechanically controlled environments. 

Air Velocity 

Air movement affects how people perceive temperature. Too much airflow causes drafts, while too little creates stale, still air. Designing for controlled, consistent air velocity helps regulate how heat is lost or retained by the body, which is key for comfort in naturally ventilated or open-plan buildings. 

Air Temperature 

Even distribution matters. A good airflow strategy ensures air temperature is balanced across the space, avoiding hot or cold pockets and eliminating uncomfortable direct blasts of hot or chilled air. 

Thermal Work Limit (TWL) 

TWL measures how much physical work a person can safely perform in a given thermal environment, factoring in air temperature, humidity, and air velocity. It’s particularly useful in industrial or warehouse settings, where safe working conditions are a WHS requirement. 

TWL is increasingly being used as a design benchmark, especially in heat-intensive environments where performance and safety need to be managed together. 

Below is a temperature and humidity analysis taken before and after the installation of natural ventilation in a client’s warehouse. 

In the first image, internal temperatures were consistently 6–8°C higher than the outside air, with relative humidity levels 20–30% above ambient, creating an uncomfortable and inefficient working environment. 

In the second image, following the installation of a natural ventilation system, the warehouse maintained temperatures just 1–3°C above ambient, and humidity dropped by 10–20%. This resulted in noticeably improved thermal comfort and air quality across the space. 

Different Types of Natural Ventilation Systems

Natural ventilation is a proven, low-energy strategy for managing airflow in industrial, warehouse, and large-format commercial buildings. But the right system depends on the building’s geometry, internal heat loads, and airflow requirements. Two of the most effective natural ventilation systems for passive extraction are ridge vents and slope vents.

Ridge and Slope Vents

Both ridge and slope vents provide passive, continuous extraction of hot, rising air, using natural buoyancy (stack effect) to draw warm air out at the highest point of the roof. These vents operate without fans, motors, or power, making them ideal for large, heat-intensive spaces. The difference lies in placement: 

• Ridge vents are installed along the apex of the roof and are best suited to buildings with symmetrical pitched roofs. 

• Slope vents are designed to be installed on one side of the roof pitch, offering greater flexibility where structural or spatial constraints prevent central ridge installations. 

Both systems are aerodynamically designed to prevent water ingress, resist wind loading, and maximise free airflow, even in low-wind or still-air conditions. Airocle’s vent designs can also be customised for weatherproofing, screening, and integration with smoke control systems. 

Use Case: 

BlueScope Port Kembla uses Airocle’s 4 Series slope vents to manage extreme internal heat loads across their steel manufacturing facilities. These vents operate continuously, 24/7, extracting hot air without power or controls. The result is a durable, low-maintenance solution that protects equipment, improves working conditions, and reduces reliance on mechanical cooling. 

Best For: 

• Warehouses or manufacturing plants with high internal heat build-up

• Facilities requiring high-volume passive extraction

• Buildings with pitched or sloped roofs (ridge vents for central ridge lines, slope vents for asymmetrical or constrained layouts)

• Environments where low-maintenance, always-on ventilation is a priority

Operable Ventilation Systems

Operable natural ventilation systems use louvres or dampers that can open and close to regulate airflow based on real-time internal conditions. These systems offer a level of responsiveness that passive-only systems cannot, adjusting automatically or manually in response to factors like indoor temperature, occupancy, CO₂ levels, or time-of-day schedules. 

These systems are commonly integrated with a Building Management System (BMS), allowing facility operators to program setpoints for opening and closing, or to respond to environmental sensors in real time. This makes them particularly effective in buildings where internal heat loads fluctuate throughout the day or week. 

Airocle’s damper options are designed for smooth operation and can be set to three distinct positions, fully open, partially open, and fully closed, allowing for precise airflow control across changing conditions. This flexibility helps maintain occupant comfort, reduce reliance on mechanical HVAC, and support energy-efficient building operations.

Image above shows the 3 positions the dampers can move within the 4 Series

Use case:
A logistics warehouse with fluctuating loading activity and high summer heat gain installed wall-mounted louvres and automated roof vents, linked to a BMS. The system opens during peak heat or CO₂ spikes and closes during cooler or inactive periods, improving air quality and comfort without mechanical fans. 

Best for: 

• Warehouses with variable heat loads or intermittent occupancy 

• Sports centres, indoor courts, and multi-use community halls 

• Projects utilising hybrid ventilation designs (mix of passive and mechanical) 

• Facilities requiring adjustable ventilation control across seasons 

Benefits: 

• Responsive to real-time internal conditions or pre-set schedules 

• Compatible with Building Management Systems for automated operation 

• Allows for airflow without compromising security or building envelope integrity 

• Offers precise control via 3-position dampers — ideal for seasonal and daily adjustments 

• Reduces reliance on mechanical cooling systems, supporting lower energy usage 

Natural Ventilation Systems with Fire/Smoke Control

Fire and smoke ventilation systems are critical for protecting life and property during fire events. Airocle offers two distinct categories of systems: 

1. Dedicated smoke and heat exhaust systems, such as the 7 Series and 8 Series, which are specifically designed to activate only in the event of a fire. These do not function as day-to-day ventilation but are integrated into the building’s fire safety strategy and can be linked to the Building Management System (BMS) or fire panel for automatic activation.
    
2. Dual-purpose natural ventilation systems, such as the 4 Series, 5 Series, and Y Series (roof and wall-mounted), which provide continuous passive ventilation under normal conditions and also act as smoke and heat exhaust vents during a fire. These systems offer ongoing airflow benefits while meeting compliance for smoke control under AS/NZS 1668.
   

Above image demonstrates how trapped smoke can be successfully ventilated through natural ventilation.  

Use Case 1: Single-Purpose Fire Ventilation: 

The Laycock Street Theatre required a fire safety solution that met regulatory requirements without ongoing ventilation. Airocle’s 8 Series roof-mounted vents were installed as dedicated fire and smoke vents; remaining closed during normal operation but automatically opening during a fire to extract smoke and heat. This protected occupants and gave firefighters safe visibility and access. The system includes fail-safe activation via fusible link in case of power loss or control failure. 

Use Case 2: Dual-Purpose Ventilation and Fire Safety: 

A Queensland boat shed required high-volume natural ventilation for heat and humidity control, as well as compliance with fire safety standards. Airocle’s 3 Series ventilators were installed, providing effective passive airflow throughout the day.  

When a fire unexpectedly broke out, the vents released smoke, allowing safe evacuation and enabling firefighters to access the space. This demonstrated the advantage of a dual-purpose system — combining natural ventilation with emergency smoke relief in one integrated unit. 

Best For: 

Dedicated Fire/Smoke Vents (7 and 8 Series): 

• Buildings requiring discrete smoke systems without daily airflow 

• Applications needing BMS or fire panel integration for automatic control 

Dual-Purpose Natural + Fire Vents (4, 5, Y Series): 

• Sites needing passive ventilation with added fire protection 

• Projects seeking to simplify systems and reduce infrastructure 

Low and High-Level Vent Combinations

How it works:
This system draws in cooler air at floor level while exhausting warm air through high-level vents, creating a natural vertical airflow driven by thermal differences. This is known as the stack effect, a widely used and effective natural ventilation strategy in commercial and industrial buildings. 

Use case:
A food storage warehouse was facing product spoilage on upper racking due to heat build-up and discomfort for workers at floor level. Installing low-level louvres and high-level ridge vents, balanced airflow throughout the space, reducing spoilage and improving comfort, all without mechanical cooling. 

Best for: 

• Multi-span warehouses 

• Bulk storage and food facilities 

• Agricultural or processing sheds 

Design Considerations: 

• Works best with consistent internal heat loads 

• Must account for wind direction, roof pitch, and obstructions 

• Can be paired with mechanical assist for added performance or code compliance 

Energy and Emissions

Because they don’t rely on motors or fans, natural ventilation systems operate with zero electricity and produce no operational emissions. 

Over 25 years: 

• Mechanical CO₂ emissions: 94.58 tonnes 

• Natural ventilation: 0 tonnes 

This makes natural systems ideal for projects targeting net zero or low-emissions performance, with added benefits for NABERS, Green Star, and ESG benchmarks.

So, why does any of this matter?

Because airflow isn’t just an engineering detail, it’s a driver of comfort, compliance, and cost. If you ignore it, you risk higher running costs, retrofit issues, and spaces that simply don’t work for the people in them. 

But if you get it right, airflow becomes invisible, doing its job quietly, efficiently, and reliably in the background. It protects your design, supports the people using the space, and adds long-term value to the building. 

And all it takes is making it part of the conversation, early. 

We’ll help you choose the right system for your space, your budget, and your compliance requirements, without overengineering it.

Speak to our team today.