When setting your thermostat, 19°C is a comfortable living temperature but only heat the rooms you use and set heating to come on in the morning instead of running throughout the night. Also don't forget to turn off heating and hot water when going on holidays if there is no risk of freezing pipes (or you have frost protection on the system which turns it on to prevent it freezing).
Finally, if you like gadgets look to get the latest smart thermostat. These can be controlled remotely via smart phones, auto adjust for seasonality and learn from how you use them to ensure you get the temperatures you want.
US EPA video on benefits of thermostats:
