Even though I live in the south, it still gets cold here, or the older I get I get cold easier. I have a small 1 bedroom apt with a 5 window sunroom. I have a gas furnace but seldom turn it on; I use a small radiator looking electric heater that I got from Home Depot (?) for about $40 a couple of years ago. My gas bill is always the minimum even though I have gas water heater and I cook with gas....my power bill is much lower during the winter even though I use the electric heater; because I HAVE to use the a.c. because of the humidity here. My heater has several settings; is on wheels and is easy for me to move from living room to bedroom. Actually, I set it on the lowest setting at night and often have to turn it off during the night.
My apts are old which means they aren't very energy efficient; however, I noticed that my windows are double paned. My sunroom was originally a porch and has been enclosed and has 5 windows along the wall. When it is really cold (like last night) I keep the door from the sunroom to living room closed. Too, I live on the first floor which means I don't get any residual heat from neighbor.
My usual attire is sweat pants and a long sleeve shirt and socks (day and n ight) unless I'm going out. My hardest moment is when I go to take a shower and have to "strip" down in the cool bathroom....augghhhh.....but it doesn't take long to get warm in the shower !