Me, personally, I would think of this as two different objects: the door is open when the sensor is closed, and vice versa. Then create either a virtual switch or a virtual sensor to represent the door. And have the state change on the sensor push the change to the virtual device.
@marktheknife , you’re probably thinking of some of the leak sensors that people have tried to use for reporting when a Christmas tree container goes dry. Those can run down the battery because of the way they work. But that won’t happen with the regular open/close sensor as @vseven explained: they just report on the state change. 