This is a question that keeps being asked by my clients.
According to The Energy Saving Trust and British Gas leaving your heating on all day is not cheaper.
They are both clear on this matter that you will save energy, and money, by only having the heating on when you need it. It is best to use a timer or programmer with a room thermostat, because they are designed to turn your heating on and off to keep your home at the temperature you set it.
The key thing to understand is that it is all about the total amount of energy required to heat your home.
It's accepted that a certain amount of energy is constantly leaking out of your home. Exactly how much will depend on how well your home is insulated. The Energy Saving Trust says that if you're keeping the heating on all day you are going to be losing energy all day - and therefore it's better to heat your home only when you need it.
Some clients complain that only having the heating on when required often means that their home is cold as it takes time to heat up, especially larger homes.
By turning on your timer/programmer a little bit earlier your home will be nice and warm.Note: Typically it takes about 30 minutes for a large flat or house to heat up and cool down. Set the timer/programmer for the heating to go off 30 minutes before you leave and 30 minutes before you return to the home. This will help you save on energy and money.