How can I dress warmly in a semi-professional environment?

I work in a small office in a warehouse. Now that its winter, its FREEZING cold. There are little wall-heaters in the room but I am wearing a tank top, long sleeved shirt, zip up hooded sweatshirt and then a zip-up polar fleece on top, and a scarf. I an contemplating leaving on my lunch break and go to target to get "hobo gloves" (with the open fingers). How else can I layer up and dress warmly?