How do mini-louvers perform?

Mini-louvers are not among the better type of intake vents available, however, in some cases they may be the only solution.

Mini-louvers are not among the better type of intake vents available, however, in some cases they may be the only solution. In general, mini-louvers will not provide enough Net Free Area to move much air through them, not enough anyway, to be used to vent most attics. For example, if an attic has 40 feet of ridgeline and 40 feet of ShingleVent II ridge vent is installed at 18 square inches of Net Free Area per linear foot that is 720 square inches of NFA total for exhaust. To balance the intake with 720 square inches of NFA using 2 inch round mini-louvers (each 2 inch round mini-louver provides .5 square inches of NFA) would require 1,440 mini-louvers.