As the other commenter posted you have solar effects, and as I stated you have other things that are putting off excess heat. For me even when it is 25 outside

As the other commenter posted you have solar effects, and as I stated you have other things that are putting off excess heat. For me even when it is 25 outside occupied my home will settle at about 40-50 or so with no heat, due to just cooking, lighting, compters, TV etc that are all outputing heat... so the delta I am attempting to heat is not really 25 to 70, but more like 50 to 70 due to the waste heat and solar heating effect For cooling I am not not only battling the outside delta, but also all of that waste heat and solar heating effects