A method for generating a value for available operating reserve for electric utility. Electric power consumption by at least one device is determined during at least one period of time to produce power consumption data, stored in a repository. Prior to a control event for power reduction and under an assumption that it is not to occur, power consumption behavior expected of the device(s) is determined for a time period during which the control event is expected to occur based on stored power consumption data. Additionally, prior to the control event, projected energy savings resulting from the control event, and associated with a power supply value (PSV) are determined based on devices' power consumption behavior. Amount of available operating reserve is determined based on projected energy savings.