Work carried out by several heating companies has shown that you will typically end up using more fuel in a like-for-like situation if you leave your heating on 24/7. This is because some heat loss will always occur due to the difference between the temperature outside your house and the temperature you are trying to maintain on the inside. This continual heat loss means more energy is used to maintain the temperature than the energy required to bring the temperature back up to the correct level if it has been switched off.
The greater the heat loss from your home, the more energy you will need to maintain the inside temperature, which means that the cost of leaving your heating on all the time will be especially expensive.
Whatever the type of heating it is essential to ensure your home is well insulated and draught proofed to minimise heat loss, see:
Typically the most energy-efficient approach to heating your home is to programme your heating system so that it comes on only when you need it most.
With many more modern room thermostats you have the ability to set different temperatures at different times, and even set up a separate programme for weekends.
When you use your boiler timer and room thermostat in combination with radiator temperature controls (TRVs), you really do have the most energy-efficient approach to heating your home.