In a typical curtain-sided house, the air inlets are located along the length of both sides of the house. In a tunnel ventilated house, air only enters the house at the end and moves down the house just like water moving through a pipe. The air entering the house can be cooled by drawing it through evaporative cooling pads or by the use of fogging nozzles located throughout the house. A disadvantage of tunnel ventilation is that more exhaust fans are required than are used in typical curtain-sided houses. The extra operational costs for tunnel ventilation must be balanced against the increase in weight gain and reduction in mortality that can be achieved during extremely hot weather.
Air movement is one of the most effective methods of cooling birds during hot weather.
As air moves over a bird's hot body, heat is removed from the bird, making it feel cooler. The greater the amount of air movement, the greater the cooling effect produced. Tunnel ventilation results in rapid air movement down the length of the house. This effect decreases as air temperature increases, but still produces cooling even when temperatures reach the mid to high 90s which are are common during Florida summers. When more cooling is desired, an evaporative cooling system is needed.