What is pressure drop and why does it matter in louvre design?

When designing or selecting louvres for building façades and ventilation systems, one factor that is often overlooked is pressure drop. Louvre pressure drop is a key factor in defining project requirements, as it must be matched to the building's ventilation needs and overall system design.

What is pressure drop?

The importance of pressure drop becomes clear when you consider how it affects airflow efficiency, energy costs, and equipment performance. A high pressure drop reduces the amount of fresh air reaching the ventilated space, placing greater strain on fans and HVAC systems. This not only increases energy consumption but can also shorten the lifespan of the equipment. Correctly sized louvres ensure that airflow is maintained without introducing unnecessary resistance, making them essential for both comfort and efficiency in building design.

Reviewing pressure drop alongside water penetration and airflow performance ensures that the chosen louvre not only meets performance requirements but also operates efficiently over time.

How do I calculate pressure drop?

Calculating pressure drop starts with understanding face velocity. This is the airflow rate divided by the louvre's free area, and it is expressed in metres per second. Once the face velocity is known, performance data supplied by the manufacturer can be used to determine the pressure drop at that velocity. Once the relationship between face velocity and pressure drop is understood, the correct louvre size can be calculated. This relationship is determined through testing and is normally shown as a graph or expressed as a coefficient of entry or discharge, which allows pressure drop to be calculated.

By considering pressure drop early in the design process, you can ensure a more efficient, reliable, cost-effective building ventilation system.