> tuning the PID controller implies loosening the “maintain the exact target temperature at all costs” spec.
And if you loosen that spec, then, as others have already pointed out, just having two setpoints, a lower one for heating and a higher one for cooling, will be sufficient as long as the difference between them is large enough (probably 2 degrees or more would be enough for many use cases). That would be simpler than adding a PID controller.
And if you loosen that spec, then, as others have already pointed out, just having two setpoints, a lower one for heating and a higher one for cooling, will be sufficient as long as the difference between them is large enough (probably 2 degrees or more would be enough for many use cases). That would be simpler than adding a PID controller.