If the inside (space) temperature is outside the range defined by the lower and upper comfort limits, the difference between the space temperature and the closer limit represents the number of degrees the mechanical equipment must make up during the prestart (optimized) period.

Whether to heat or cool depends on the direction that the space temperature must move. The component multiplies this run-time value by the temperature differential to determine the number of run-time minutes required to achieve the comfort limit at occupancy time, as defined by the schedule's start time.

This is the best time to start heating or cooling before the scheduled start for the day. If the system’s time is later than the schedule’s time offset by the calculated lead time, the component enables optimum start outputs.

If the inside (space) temperature is inside the range defined by the lower and upper comfort limits and if the schedule’s status is active, the difference between the space temperature and one of the limits (depending on the mode) represents the number of degrees the temperature can drift between the time the mechanical equipment is stopped and the schedule’s inactive event time.

The drift (lead time) calculation is similar to the one for start time but using the drift-time heating and cooling factors.

The component invokes the optimum stop time for each of the schedule’s inactive events based on the drift time and Next Event Time value.