* Cross Sectional Area = Width (ft.) x Height (ft.)

Example: A laundry 100' x 30' x I5'. Based on pulling air through l00 ft. length, the fan CFM required is determined as follows:

Cross Sectional Area = 15' x 30' = 450 sq. ft.
Desired Velocity = 150 ft./min.

CFM  =  450 x 150   = 67,500 cu. ft./min.

Influence of building size on velocity selected 
As building size increases, there are factors that will affect the average air velocity through the cross section of the building. The longer the building, the greater the amount of air leakage from windows, doors, elevator shafts, etc. To offset this air leakage, air velocity should be increased. This is done by relating the calculated velocity to the length of the building. The results will provide an effective velocity of approximately 150 ft./min. The table below gives the velocity recommendations in terms of the length of the building. 

Zone Cooling 
In some buildings. it is not possible or practical to install a complete ventilation system. In such situations, zone cooling may be effectively used. The problem is similar to a spot cooling application, but usually involves a relatively larger area. Effective zone cooling may be accomplished by use of air circulators. See Air circulation below.
     A very satisfactory zone cooling method is the use of supply-type PRVs to flood the problem area with fresh, cooler air. The adjacent drawing and zone cooling table illustrate the capacity of several American Coolair PRV models to effectively cool an area. The figures are based on discharge of air approximately l5 feet above floor level. it is recommended that an American Coolair sales engineer survey your problem area and recommend equipment to fit your specific needs.

Air circulation 
Air circulators may be effectively used to boost air velocity through large buildings that have a flow pattern difficult to control. Air circulators are also used to redirect air into occupied areas near floor level. The drawing below illustrates each of  these uses in a breeze conditioning system based on air velocity. 

     Air circulators are also effectively used in locations where adequate exhaust and supply air fans may be lacking. Air circulation alone may provide heat relief and cooling comfort to individuals in the area. American Coolair's Type CABL fan is ideally suited to this application. For many installations, fans like this may be positioned 8' to 10' above the floor and at approximately 50' intervals to obtain a continuously circulating column of air across a room or building. To broaden the column of air, fans should be located abreast of each other 15' to 20' apart. Fan locations and positions are easily adjusted to the requirements of the area. 

Combination of methods 
If a relatively straightforward breeze conditioning system is possible, the rate of air velocity method outlined above should be the basic method used. However, there may be rooms or areas within the building that will require special treatment. If so, one of the other methods, such as spot cooling or zone cooling, may be combined with the basic method to achieve the over-all objectives.