Since we just moved into this current rental house at the end of last February, and so we haven't really had to deal with cold weather...until now. Compared to what the folks in the Northeast have been dealing with, it seems lame to talk about weather being an inconvenience, but, well, it was cold last night...down into the mid 20's...and we learned this rental house doesn't hold heat very well.
I already figured it might be bad...the windows are older(aluminum frame), and with it being a single story house with central heat and air, the thermostat, located in the living room doesn't always tell the truth about what the temperature is down in the bedrooms.
It doesn't help that my wife and I have diametrically opposed views as to what 'comfortable' is. I like to leave the thermostat set at about 66-67 degrees during the day and evening, and at that temperature, I am comfortable in gym shorts and a t-shirt, sometimes wearing slippers if I have to leave the carpet. In those conditions, my wife is usually wearing fluffy socks, flannel pants and a hooded sweat-shirt while snuggling with a blanket on the couch.
So... the space heaters are a compromise. We can run one in each of the girls room about an hour before bedtime, and then when they go to bed, put one in the hallway, and one in our room, to warm it up before we get into bed. In the morning, I turn on the one in our bedroom(because, it is nice to have some warm air when you get out of the shower), and then kick the one on in the hallway for about an hour.
This way, I get to turn the whole house heat down to 64(maybe even 63!).
If I was a real geek, I'd have some kind of 'real time' use-meter hooked up to our electrical system, and see which way used more power...