Back to News
Whether you’re working on a high-security data centre or a high-performance hospital, selecting the right louvre isn’t just about aesthetics—it’s about precision. The right louvre balances airflow, rain defence, vision screening, and pressure drop, all while aligning with the project’s functional and architectural intent.
Here’s how to make sure you’re specifying the right one.
First things first: make sure the louvre you’re considering is tested to Australian Standard AS 4740:2025. This standard sets out a rigorous method for testing both rain defence and airflow performance, using fixed face velocities and controlled wind-driven rain simulation.
This ensures your louvre has been tested under Australian conditions—not just a generic overseas standard—and provides comparable data you can trust.
Everyone wants 100% airflow and 100% rain protection. Unfortunately, physics says otherwise. The better a louvre is at stopping rain, the more it restricts airflow—and vice versa.
AS 4740:2025 classifies rain resistance from Class A (≥99% effective) to Class D (<80%) and airflow performance by Discharge Loss Coefficient (Cd), where a higher Cd means better airflow. Selecting the right balance depends on what your project prioritises—ventilation efficiency, weather tightness, or both.
Percentage free open area has long been used to assess louvres—but it’s outdated and misleading. It doesn’t account for real-world airflow rates, pressure drop, or weather resistance. In fact, AS 4740:2025 doesn’t use this metric at all.
If you're comparing products based on free area percentages alone, you’re missing the bigger performance picture.
The right louvre is the one that meets engineering, architectural, and compliance needs. That means the mechanical engineer must define the required airflow (m³/s) and allowable pressure drop (Pa), while the architect ensures the louvre meets façade aesthetic and screening goals.
Together, these inputs help balance façade area against the louvre’s effective aerodynamic performance and rain resistance.
Select a louvre that’s been tested, rated, and proven. Always refer to published data sheets or draft specifications to ensure your selection meets the brief.
Selecting a louvre is about more than ticking boxes. It’s about choosing a performance-tested solution that contributes to the long-term success of the building’s façade and function.
At Louvreclad, we test every product against Australia’s toughest conditions—so your project doesn’t just meet standards, it redefines them.
Need guidance? Speak to our experts for tailored support on your next project.