Abstract: A system for detecting a control loop interaction between two or more control loops. The system includes a processing circuit configured to store a history of detected loop disturbances for a plurality of control loops. The processing circuit is also configured to compute a measure of interaction between control loops using the history of detected loop disturbances. The processing circuit is further configured to determine whether a loop interaction exists based on the computed measure of interaction.

Abstract: A method for controlling an economizer in a building HVAC system includes providing a manipulated variable as an input to a control process, holding the manipulated variable at a first extremum during a first portion of an evaluation period, and applying a dither signal to the manipulated variable during a second portion of the evaluation period. The dither signal causes the manipulated variable to deviate from the extremum. The method further includes monitoring a variable of interest output by the control process during the first and second portions of the evaluation period and switching the manipulated variable to a second extremum opposite the first extremum in response to the variable of interest moving toward an optimal value during the second portion of the evaluation period.

Abstract: Systems and methods for estimating a time to cool down or warm up a building zone from a temperature setback condition are provided. A described method includes determining, by a controller for the building zone, at least one of a cooling demand for the building zone and a heating demand for the building zone for a time period corresponding to the temperature setback condition. The method further includes estimating a return time using at least one of the cooling demand and the heating demand. The return time is the time to cool down or warm up the building zone from the temperature setback condition.

Abstract: A system for detecting a control loop interaction between two or more control loops. The system includes a processing circuit configured to store a history of detected loop disturbances for a plurality of control loops. The processing circuit is also configured to compute a measure of interaction between control loops using the history of detected loop disturbances. The processing circuit is further configured to determine whether a loop interaction exists based on the computed measure of interaction.

Abstract: A system is disclosed for detecting faults in an environmental control system for a building zone. The system includes a circuit configured to determine that a fault exists based on a comparison of the current value for the climate condition in a heating state and the estimate of the climate condition at which a transmission from the heating state to the no heating state is expected to be caused by a finite state machine of the system.

Abstract: A system is disclosed for detecting faults in an environmental control system for a building zone. The environmental control system is controlled by a finite state machine that causes states of the environmental control system to change based on a varying climate condition. A circuit is configured to receive a current value for the climate condition when the environmental control system is in a heating state and to calculate an estimate of the climate condition at which a transition from the heating state to a state of no heating by the environmental control system is expected to be caused by the finite state machine. The circuit is configured to determine that a fault exists based on a comparison of the current value for the climate condition in the heating state and the estimate of the climate condition at which a transition from the heating state to the no heating state is expected to be caused by the finite state machine.