SEPARATING INDOOR AND OUTDOOR ENVIRONMENT
A louver is a ventilation product that allows air to pass through while keeping out unwanted elements such as water, dirt, and debris.
A number of fixed or operable blades mounted in a frame can provide this functionality. The basic considerations for selecting louvers are mentioned alongside.
It is the ratio of total open area obtained after subtracting all the obstructions and overall window opening. Generally ranges from 35% to 60%. A high percentage free area is beneficial because more air can enter into a smaller wall opening, reducing the cost of wall opening and the louver.
It is a threshold measurement of air intake velocity at which the louver will begin leaking. Generally ranges from 500 to 1300 fpm and shall be selected so as water penetration shall be higher than the air intake velocity.
RESISTANCE TO AIRFLOW
Every louver will create resistance based on the frame and blade shapes. Lower blade angles or more aerodynamic shapes create less resistance. We can calculate the pressure loss of the louver at the required free area velocity and determine it's suitability. The resistance created can be detrimental to the application of fans and other air movement equipment, so we should attempt to minimise it.