How do you know if the heater is active or idle when viewing the thermostats in the app or online. Obviously if the current temp is the set temp or rising, but there is no way to tell the current status of a unit?
A thermostat calls for heating/cooling activation by internal relays when the current temp exceeds the set point by a value set by the thermostat, 1 degree, 1.5 degrees, etc.
If the current temp exceeds that value, there is a call for heat or cool, depending on the mode and temp and applicable installation settings of the thermostat. The current temp and mode themselves are indicative of a call for heat or cool.
In order to have specific usage tracking, the thermostats and HVACs would need to support this. If I recall, most compatible Z-wave thermostats (perhaps all) do not support usage tracking in this way.