When it comes to the modern broiler house there have been significant advancements in virtually all the components of the environmental control system. Tunnel fans have progressed from simple 48" box fans to state of the art 50"+ fans with discharge cones, interior shutters shaped like air foils, and high efficiency motors. The combination of these changes has increased the overall energy efficiency of tunnel fans by as much as 50% over the last ten years. Poultry house evaporative cooling syste...ms have evolved from interior low pressure fogging systems, to fogging pads, to high efficiency six-inch pad systems that maximize cooling of incoming air while keeping house moisture and management time to a minimum. Heating systems have progressed from individually controlled pancake brooders, to zonecontrolled radiant brooders, and in some instances, radiant tube brooders. Controlling all this equipment, once done with simple mechanical thermostats, is now done with modern microprocessor-based environmental controllers that precisely control and coordinate all heating and ventilation system components to give the broiler producer a high level of control over environmental conditions within their houses. With all these changes, there is one environmental system component that has changed little over the last 15 years: the galvanized side wall inlet.