Basic the title says it all. I did not get Nest, or Energenie to use geofencing or occupancy detect, but since it was there I have tried using it. However in the morning when heating moves from Eco to Comfort (17°C to 20.5°C) the wall thermostat is programmed to heat to 19°C then 0.5°C per hour until at 20.5°C as observations have shown hall may be at 19°C but the electronic TRV heads have got the other rooms to temperature well before the heat from hall radiator has reached the wall thermostat. So the home heats as wanted, after an over night reduction. However leave the home and the heating turns down, but on return it goes to 20.5°C and if it has cooled over 0.5°C while out it will over shoot, how much will vary. Over shooting means around an hour latter the hall is still over the target temperature but all other rooms are below target temperature the electronic TRV head can't heat a room if central heating not running. If I remember I will turn down hall thermostat on arriving home, then turn it up again latter, so it heats in two or more stages, but most times I forget until an hour or so latter when I am cold. So the question is geofencing or occupancy detect worth it? How much fuel do it really save, OK heating off for say 6 hours, home cooled to 18°C to 19°C, and the boiler has an extra long run to reheat, so not simply 6 hours saving as reheat uses fuel, and since it over shoots loses are increased, sure it must save some fuel, but does it save enough to be worth it? Since boiler supplied from a FCU can't use a plug in energy meter to monitor how long it runs. The Nest report Says I didn't use the heating Tuesday and Monday that is clearly not correct. And even if it was, it shows demand for heat, not the boiler running, the boiler switches off/on when heating the mark/space ratio will depend on how many electronic TRV heads are calling for heat. So is all the geofencing or occupancy detect worth it? Does it really save enough money to be worth having a cold evening because it has over shot again?