Architectural louvre systems have been used in buildings for hundreds of years. Louvres used in churches and similar buildings in the olden days were made from stone or timber and were generally simple, single blade arrangements that would often be very deep if they were providing rain defence.
Louvre systems have evolved significantly since ancient times with modern louvre designs offering different blade profiles and performance characteristics.
Flat Z Louvre Blades
Essentially aluminium versions of the early louvre designs featuring a flat profile, flat Z louvre blades offer good airflow, but provide poor defence against rain, making them ideal only for screening applications.
Drainable Louvre Blades
The most commonly used extruded blade type up until the late 1980s, drainable blade louvres offer reasonably good defence against light rain, but generally don’t perform well in wind-driven rain conditions.
High Performance Louvre Blades
High performance louvre blades with integral water collection and drainage are designed to prevent wind-driven rain from entering the building, while allowing efficient passage of air. Air entering the louvre is forced to rapidly change direction creating low vortex turbulence and areas of low and high pressure. Water droplets are thrown out into the low pressure areas, draining away through the jambs or mullions, while the air carries through the louvre. This process is called tangential separation.
True high performance rain defence louvres are expected to collect water from the air and also drain it away. If the water isn’t properly drained away, it will cascade down the louvre face and enter the building.
Construction Specialties - C/S advises that architectural louvre systems should be selected based on the needs of the building. For instance, flat blade louvres are ideal for areas that require little or no rain defence, but areas that have expensive plant equipment need a high performance louvre blade system to avoid getting wet.
Image: High Performance Louvre Blades