An energy management system controls electrical load operation to maintain the loads' energy usage below a maximum energy limit. An OFF priority list specifies enabled loads that can be disabled, with an enabled load having higher priority if further from the load's action threshold (such as a desired operating temperature). An ON priority list specifies disabled loads that can be enabled, with a disabled load having higher priority if closer to the load's action threshold. If the collective loads' energy consumption is below a control energy level set below the maximum energy limit (preferably by an amount approximating the projected consumption of the largest disabled load), the load atop the ON priority list is enabled and moved to the OFF priority list. If the collective loads' energy consumption is above the control energy level, the load atop the OFF priority list is disabled and moved to the ON priority list.