Peak Demand Limiting (PDL) helps companies manage their electrical consumption during periods of peak demand.

PDL reduces the electrical consumption of a building control system by shedding loads (turning OFF equipment) when the electrical demand exceeds a setpoint.

Loads are restored (equipment is turned ON) when electrical demand falls below the setpoint. However, the equipment remains OFF if restoring the load will exceed the setpoint.


PDL is monitoring an electrical meter that supplies power to three air handling units and some auxiliary equipment. Two of the air handlers are currently ON while the third air handler is about to be turned ON. If all three air handlers and the auxiliary equipment are operating at one time, PDL predicts that electrical demand will exceed the peak setpoint of 500 kWh.

To keep electrical demand from exceeding the setpoint, PDL shuts OFF (sheds) the auxiliary loads that are not critical. Once the building is operating at a level where the electrical demand will stay within the setpoint, the auxiliary equipment will be restored.