I always "love" this thread theme as every time it comes up (on a regular basis
) there are so many opposite views - lol. Hence why I said a detailed parallel test would be great to put this to bed once and for all
The "bit" that always nags me about the theory is that if we just consider the air in a room then absolutely it doesn't make a difference whether I heat from cold or maintain a temp, the energy used for the period of heating must be identical as per MajorDanby post. However, if we now add in thermal mass heating ie the heat required to raise the walls, furniture etc so that they become heat emitters (ie mini rads) rather than heat consumers (emitting cold and making the room "feel" cold), then that is the bit that I wonder whether there is an advantage in keeping the room at a higher constant temp (Unless in a highly insulated property with very low thermal mass requirements) so that the room "feel" factor is constantly maintained. I appreciate that this "feel" factor is somewhat unscientific and so on pure energy and temp I expect MajorDanby post and Killa47 Martin Lewis reference are, in absolute energy terms, the “facts of the matter”