My landlord has fitted all heating radiators with electronic thermostats, namely the Honeywell Rondostat. They can be programmed with two temperatures (cold and warm) and two time intervals per day where it should be on the warm temperature. Usually one does weekdays in the morning and evening, and weekend from morning until nighttime. They measure the temperature and adjust the valve accordingly.
This is quite nice and likely saves a lot of heating. Most importantly one can just come home and find the rooms to be in the warm or cold setting that one wants.
These things have two major drawbacks though: Open window detection and batteries. The automatic detection of open windows sounds quite nice, just open the window and the very cold air will tell the thermostat to shut off. In reality I let it turn off a few minutes before I open the windows. And when I have closed them, I want it to start heating right away. But it usually won't let me, assuming that the window is still open because it is so cold now. Basically one has to wait five minutes before it starts heating again. Good intentions, but it actually hurts more than just doing nothing special would.