HVAC system with multi-state predictive free cooling control

A heating, ventilation, or air conditioning (HVAC) controller for equipment, the HVAC controller comprising:

• one or more processors;
• and
• one or more non-transitory computer-readable storage media communicably coupled to the one or more processors and having instructions stored thereon that, when executed by the one or more processors, cause the one or more processors to:
• operate the equipment to execute a first process in a first state to produce a resource by mechanical cooling;
• operate the equipment to execute a second process in a second state to produce the resource by free cooling;
• predict whether the second process will be available for at least a minimum second state operating time during a plurality of future time steps, wherein availability of the second process is determined based on outside air temperature;
• transition the equipment from operating in the first state to operating in the second state in response to a prediction that the second process will be available for at least the minimum second state operating time;
• and
• transition the equipment from operating in the second state to operating in a third state during which the equipment does not produce the resource in response to a determination that the second process is unavailable and predicted to remain unavailable for less than a minimum first state operating time required to transition back to the first state.

A method for controlling equipment in a heating, ventilation, or air conditioning (HVAC) system, the method comprising:

• producing a resource by mechanical cooling by operating equipment to execute a first process when operating in a first state;
• and
• producing the resource by free cooling by operating the equipment to execute a second process when operating in a second state;
• predicting whether the second process will be available for at least a minimum second state operating time during a plurality of future time steps, wherein availability of the second process is determined based on outside air temperature;
• transitioning the equipment from operating in the first state to operating in the second state in response to a prediction that the second process will be available for at least the minimum second state operating time;
• and
• transitioning the equipment from operating in the second state to operating in a third state during which the equipment does not produce the resource in response to a determination that the second process is unavailable and predicted to remain unavailable for less than a minimum first state operating time required to transition back to the first state.