Re: @Kieren McCarthy
But is it even worth turning the heating off and on? I wouldn't want the inside of my house to get colder than 5C, ever, and I wouldn't want it to get colder than 10C when there are living occupants (cats, dogs, etc). I never want it warmer than 15C. Experience shows that the heating never needs to be on until we hit the time of year where outside daytime temps are below 10C.
So in the time when we are all out (which, for a large family is much less than would be the case for a single person. Nevertheless, I find the house cools quite slowly, which suggests the heat loss is fairly low. But if it's freezing outside and 15C inside then, turning the heating off and allowing the house temperature to drop a degree is only going to decrease the cooling rate by a few %. Ok, if we let it go down to 10C we have reduced the heating loss by 1/3, BUT it takes hours before it is that cold --- most of the cooling is at a higher rate.
Isn't it best just to have a well insulated house and keep the thermometer at the same level? I'm really curious as to how much these systems save.