How is airflow performance measured in louvre systems?

Airflow performance in architectural louvre systems is typically measured through controlled laboratory testing to determine the pressure drop across the louvre at a range of airflow velocities. This testing indicates how much resistance the louvre introduces into a ventilation system and therefore how efficiently air can pass through it.

A key outcome of this testing is the Coefficient of Discharge (Cd)—a dimensionless value that compares the actual airflow through the louvre with the theoretical airflow through an ideal free opening. A higher Cd indicates a more aerodynamically efficient louvre, with lower resistance and a lower pressure drop.

In some engineering contexts, the Coefficient of Entry (Ce) is also referenced. Ce describes how efficiently air enters the louvre opening and is closely related to Cd. In architectural louvre testing, Cd is the industry standard, and while Ce may be used in more detailed airflow modelling, both values generally correlate, with Cd representing the overall aerodynamic behaviour of the louvre.

Airflow performance data is typically presented as a graph showing pressure drop (Pa) against face velocity (m/s), enabling M&E consultants and designers to understand the impact on fan selection, plant sizing, and ventilation performance.

Airflow should always be considered alongside other key parameters—such as free area, weather resistance, and acoustic performance—as optimising one characteristic may affect another.

At Solinear, our Aquarius X-LINE architectural louvre systems are independently tested to relevant industry standards to provide accurate airflow and weatherability data. We assist design teams in selecting the most appropriate louvre profiles and configurations to achieve the right balance of airflow efficiency, weather protection, and façade integration.