Louvers provide ventilation allowing air to pass through a window while at the same time keeping unwanted elements such as dirt, water, and other debris out. Exterior architectural louvers feature a number of fixed or operable blades that are mounted in a frame. There are many factors to consider when dicing upon louvers.
Factors
There are certain factors to consider when deciding upon louvers for any residential or commercial property include. These factors include; free area, water penetration, and resistance to airflow or pressure loss. By fully understanding these concepts the proper louver will be applied.
Free Area
To determine the free area, it's important to take the total open area of the louver. This is done by subtraction all the potential obstructions such as blades and the actual frame and then diving the overall wall opening. This then allows for a comparison of the louvered opening as opposed to an unobstructed opening. The common range for louver free areas is about 35% to 60% of the wall opening. Having a high percentage of free area is very beneficial. This will allow for more air to enter a smaller wall opening, this will therefore, reduce the cost of the wall opening as well as the louver.
Obstruction
Some obstruction is needed in order to keep unwanted water out. A full obstructed opening would allow for no water to enter, while a totally unobstructed opening would allow for water to enter unhindered. A louver that is properly designed will be able to maximize the free area while at the same time allowing for a minuscule amount of water to enter.
Water Penetration
To establish the water penetration of a louver, the air intake velocity must be determined. The first point of water penetration is the point at which a louver will let water pass through the louver. By taking the threshold measurement of the air intake velocity the proper penetration will be considered. By factoring in water penetration the proper louver can be installed.
Resistance to Air Flow
Any obstruction that is in the air stream will create a resistance. This includes louvers, coils, filters, ductwork, the structure of the building, the list goes on. The actual resistance provided by the louver can be determined by measuring the running air through the louver while also measuring the pressure differential at a variety of free area velocities.
Aerodynamics
All louvers create a resistance. This resistance is based upon the frame of the louver as well as the shape of the blade. Lower blade angles or those that have more aerodynamic shapes will create less resistance. In order to fully consider the resistance to airflow the free area velocity allowed by the louver must be calculated. It is important to consider the resistance as well as minimize it, as it can be detrimental to the application of flans or other air moving equipment.
When deciding on exterior architectural louvers it's very important to consider the factors of free area, water penetration and pressure loss. By taking all these considerations into effect a proper decision can be made when installing louvers. In addition to adding protection from water, dirt, and other air debris, they also act as a sun control louver. Their full functionality and design allow them to be an added feature of any residential or commercial residence.
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