Of course I have my heat on. It's way too cold outside and I need it to be 20 degrees Celcius during the day if I'm home, up to 21 in the evening.
I live in an apartment and it usually keeps quite warm because of my below neighbour heats his place 20 night and day. It's a blessing and a curse, really. Waking up in a warm room is something I really dislike, but at the other hand I don't have to spend as much money on my electricity bill. If it'll freeze a bit it will cool down enough to wake up to a nice 17 degrees. I love cold in the morning. I only have to heat at night and then I don't go overboard because I like laying on my couch on my onesie and with my blanket. And I usually keep the ventilation grids open on the windows, unless the wind is blowing right in.