Optimal Stop is a control algorithm that deactivates heating or cooling equipment at calculated times before building occupancy ends, allowing natural temperature drift to reach setpoint at occupant departure. This strategy reduces unnecessary equipment runtime and energy consumption during the final occupied hours.
Operation Principle
The controller predicts outdoor and indoor temperature trajectories to determine when to stop conditioning. On a winter day with 60°F outdoor temperature and 70°F setpoint, the system may stop heating 20-30 minutes before closing time, allowing temperature to naturally decline. The algorithm continuously adjusts based on actual weather conditions and thermal mass response.
Practical Application
Optimal Stop works best in buildings with significant thermal mass and predictable occupancy schedules. Office buildings, schools, and retail spaces achieve 5-10% additional energy savings when combined with other scheduling strategies. The system requires accurate weather data and well-calibrated thermal models. Implementation prevents discomfort by ensuring temperature remains within 2-3°F of setpoint at occupancy end, maintaining acceptable comfort conditions while minimizing waste.