Abstract: Power demand control in a plant facility is improved by allowing the demand limit imposed as a target to be met at the end of a control period to follow the actual demand in the plant. The demand limit is automatically optimized as actual demand fluctuates and it is set in accordance with past history.

Abstract: An energy conservation schedule is followed automatically in response to production activity in a plant facility. The demand of power from the utility company is used as an indicator of actual production activity. The ON/OFF ratio of non-production loads is reduced to conserve energy and such adjustment is automatic in relation to actual demand of power. In one embodiment of the invention, a higher level of constraint is imposed on the non-production loads as soon as the demand has passed a critical threshold downward. In a second embodiment of the invention, control of the demand is installed in the plant in order to meet a demand limit at the end of a period of control involving the production loads as well as non-production loads under constraints. In the latter situation, whenever demand control is ineffective for a full control period to affect switching of the production loads, the system goes to energy conservation with a higher level of constraints applied to the non-production loads.