Is it weird that I use my girlfriend as a radiator at night?
Do you both enjoy it or does she mind?
I do it because I love her and I like to sleep together with something warm.
It's hard being cold. It can be seen as dehumanizing to compare your girlfriend with an object and shouldn't be treated as a heater. You should get a small heater if you can't heat your home.
Of course, I don't like the cold either. I think everyone has to take care of their own space.
It sounds like both of you enjoy cuddling at night and sharing heat. As long as you both enjoy it and your not doing it to save on your heat bill, there's no problem.