This article describes the spatial and diurnal patterns of air temperature and relative humidity (RH) in commercial-scale broiler houses (12 ¥ 122 m, 40 ¥ 400 ft) using experimental conventional and tunnel heating, cooling, and ventilation systems. The experimental broiler houses used 76-cm (2.5-ft) side curtains and combined mechanical and natural ventilation. Heating was provided by propane brooders and space furnaces. Cooling was accomplished with side-mounted cooling fans and misting nozzles in the conventional houses, but with fans and evaporative cooling pads in the tunnel houses. Interior mixing fans, arranged to circulate air in a “racetrack” fashion, were used in the tunnel houses.