What do you consider cold? When would you put a coat on, keep the windows shut, put the heating on? I'm in Sheffield, the past 2-3 weeks have been very cold for me, and I kept the heating on at around 21c I'm indoors right now and it's 12-13c (outside) I have windows wide open and I feel cold, well my arms anyway (wearing a T shirt). I remember when I was younger talking 5-6 years ago I would go out in just T-Shirt while it was snowing and not feel cold. So I'm trying to get used to it again (hence why the open windows). Is there a general temperature that is deemed "cold" for humans? Is it personal? When "should" I turn the heating on or close the windows? When do you? If I feel cold, should I just get used to it? Should I put on a jumper? Close the windows put the heating on? Cos 12c doesn't SOUND cold to me, but it sure feels it. So I'm trying to get used to it.