A load control system (100) for controlling the amount of power delivered from an AC power source to a plurality of electrical loads (lighting load 212, plug-in load 224, damper 242 of an HVAC system, discharge lamps 314, electronic drive unit 326) includes a plurality of energy controllers (dimmer switch 210, plug-in load control 220, temperature control devices 230, 330, contact-closure output pack 240, digital ballast controller 310, motorized window treatment 320). Each energy controller is operable to control at least one of the electrical loads. A broadcast controller 180 transmits wireless signals to the energy controllers. The load control system includes a plurality of independently-controlled units (or sub-systems 110, 112) having commanders (remote controllers 250, 350, occupancy sensors 260, 360, temperature sensor 270, daylight sensor 370) for controlling the energy controllers, where the independent units are configured and operate independent of each other. The energy controllers do not respond to control signals received from the commanders of other independent units. The energy controller may operate in different operating modes in response to the wireless signals transmitted by the broadcast controller. The broadcast controller is also operable to discover nodes, to receive digital messages from the commanders and energy controllers and to collect data from the commanders and energy controllers of the independent units. The load control system enables system-wide functionality, such as demand response and whole-building time clock functions.