Well heating with oil is pretty expensive. My house is set to 21.5 now, nice and cosy. Fuck the bill. You can close of vents in unused rooms, but IMHO prolonged exposure to low temps is probably not good for your body, joints, muscles etc... especially if you are not used to it. (i.e no an Inuit). Maybe eat some seal blubber.. I hear that's what the folks that really have to live with extreme cold do. But yeah, -15 today, all that snow, it sucks.