Energy efficiency

[tdm]

Is it more efficient to leave heating on all day or only put it on for a few hours morning and evening (with the house temperature dropping massively inbetween)?

[ethelb]

I think it depends how long you spend in the house tbh. I'm out for 10 hours a day. And generally only have it on at night when it is v cold. So i really cna't beleive it is more efficient to have it on all the time than for 3 hours in the evening.

[PigletJohn]

is this your own house, or rented?

how thick is the loft insulation?

does it have cavity walls, and are they insulated?

how old is your boiler, and is it a combi or does it have a cylinder?

what size is the radiator in your bedroom, and what size is the bedroom?

(these are all clues that will give pointers about other things)

but

Heat transfer from a hot object to a cold one is directly proportional to
1) temperature difference
2) time
and some other things

so keeping the inside of your house 10 degrees warmer than the outside for 24 hours, will lose twice as much heat as keeping it 10 degrees warmer for 12 hours. Keeping it 20 degrees warmer than the outside wil lose twice as much heat as keeping it 10 degrees warmer.

There are additional comfort quibbles about how long it takes to get warm from cold, and how long it takes to get cold from warm, and how many hours a day you are at home, but they do not affect the laws of heat loss.