I am not suggesting that people in extreme cold climates not heat their house at all and burst pipes, etc. but you could, for example heat your house to 65F ins

I am not suggesting that people in extreme cold climates not heat their house at all and burst pipes, etc. but you could, for example heat your house to 65F instead of 72F and use about 25-30% less heating energy, and still keep family members that like it warmer comfortable. If you drop it to 60F that uses close to half the heating energy on average that heating to 72F. Personally, I live in a mild climate where it rarely gets below 50F or over 85F outside, and I just leave the windows open year round and let the house fluctuate between about 60F and 80F, and find it very comfortable without using anything but different clothing. It is interesting that even with all of the windows open the house averages out the evening lows very well, and stays about 10F warmer.