What is 'schedule-based control' in DDC?

• A. Using time-based or occupancy-based logic to adjust setpoints or sequences.
• B. Controlling strictly by current sensor values.
• C. Randomizing control actions to test stability.
• D. Relying solely on manual operator input.

Answer: (A)

Schedule-based control uses time-of-day or occupancy information to change setpoints or sequences in a DDC system. This means the controller follows a programmed schedule or presence data so the system behaves differently at different times or when spaces are occupied, optimizing comfort and energy use. For example, you might raise the cooling setpoint and reduce ventilation when a space is unoccupied, then revert to tighter comfort settings when people are present. This approach differs from relying only on instantaneous sensor readings (which ignore planned patterns), from randomizing actions (which isn’t a control strategy), or from depending solely on manual input (which removes automation and schedule). The key idea is pre-programmed behavior that follows a schedule or occupancy cues to adjust how the system operates.