Fans used in air-handling systems often have a significant impact on energy use and acoustics. How much of an impact depends on howa fan is selected, installed, and operated. This broadcast discusses fan performance curves and fan laws, different fan types (fanblade shape, housed vs. plenum fans, direct-drive plenum fans, fan arrays), how a fan interacts with various types of systems, considerations when selecting a fan (efficiency, acoustics, footprint), and the ASHRAE Standard 90.1 fan power limitations.