IS air inlets are designed to be used as ceiling or roof inlets in livestock structures. The patented Star Diffuser ensures that the incoming air stream is accurately controlled and radially distributed to create a uniform climate inside the structure. During cold periods, the cold incoming air should be heated before it makes contact with any animals housed inside a structure. For this purpose, the unique design of the star diffuser directs air horizontally out when it is set to small openings. This allows the cold incoming air to be mixed with the hot air that is found near the roof of the structure. If a ceiling is installed, the air can be directed along the ceiling. Doing this use can be made of the Coanda effect in which the airstream “sticks” longer to the ceiling. This allows for more mixing time between the cold incoming air and the hot air near the ceiling. During hot periods, the ventilation demand for livestock structures increases and it is no longer necessary to heat up the incoming air before it comes in contact with the animals. The star diffuser responds perfectly to this change in ventilation demand. As the blades of the diffuser open more, it starts to direct air down towards the animals, thereby supplying more air directly to the animals.