An uninterruptible power supply (UPS) system includes an enclosure and a plurality of power converter modules positioned in the enclosure, each power conversion module including a power converter circuit, a module controller circuit configured to control the power converter circuit and at least one module fan controlled by the module controller circuit. The system further includes a system controller positioned in the enclosure and configured to communicate with the module controller circuits over a communications bus and at least one exhaust fan configured to exhaust air from the enclosure and controlled by the system controller. The system controller is configured to control the at least one exhaust fan responsive to information, such as temperature and/or load information, received from the module controller circuits.