The system does exactly that - But that is done automatically without intervention.
The system recognises by checking on our devices and the presence detectors if we are at home.
If we aren't it reduces the temperature.*
Then it looks into our calendars when we can be expected to be back and increases the temperature accordingly (additionally once we enter a certain Geofence).
*:The overall heating effort is also based on the current and expected weather and sun-influx,as I have some rooms that basically heat themselves when the sun is out.
The system is using that effort to adjust shades (e.g. it would allow a lower living room temperature in the morning after we left when it knows that there will likely be a sunny afternoon heating the room without the need to add external heat)
This is what I mean with smart: A smart system is only smart if the user doesn't have to fiddle around with it. Everything else is a remote.
(My next goal is to add personalised heating. I want the system to recognise who is/comes home and adjust the temperature accordingly as my wife wants other temperatures as I do. O can do it room based, e.g. the kid's room is adjusted according to the kid being there, but overall I am not quite there yet)