As covered in a number of past newsletters, selecting the right tunnel fan for a new house or one that is being retrofitted to tunnel ventilation is one of the most important decisions a producer has to make. The right tunnel fan will not only insure maximum bird cooling during hot weather, but can lower fan operating costs 25% or more, resulting in thousands of dollars in savings each year. Trying to compare tunnel fans may seem like a nearly impossible task. First you have to figure out how ma...ny of each type of fans is required to produce the desired air exchange and air speed. Then you have to compare energy efficiency ratings to see which fan is more energy efficient, not really knowing how much a difference of 2 cfm/watt is really going to save you each year. Last but not least, you have to compare the fans based on their air flow ratio. Should you pick the fan with the 0.80 air flow ratio or the one with the 0.70? These are hard decisions to make considering you are not sure what difference it is going to make when it comes to keeping your birds cool when it is 100oF outside. It is little wonder with all that is required to properly compare tunnel fans that many producers end up selecting fans based on which one moves the most air or which one is the least expensive.