Working outside in all kinds of weather has acclimated me to cold pretty easily. Learned a few tricks though, like eat spicy food or something else to raise your internal thermic temp. If you're skinny, try eating at McDs every so often, as a little more fat is good insulation. Exercise to raise metabolism always makes you warm inside too. I usually wear shorts and a t-shirt all the time inside as I'm pretty tolerant to temperature. Try a heavy weight t-shirt and some of the heavier weight shorts that are basically sweatpants with the legs cut down.