I work as a therapist in an also over-airconditioned office, and survived winters studying in college without a heated dorm unit 🥶 For tops, i like wearing sweaters, flannels, and other long sleeve blouses and button downs. Thermal under-layers work amazingly well and are thin enough to wear under office clothes; I’m a fan of uniqlo heat tech and 32 degrees from costco. I also wear more “fashionable” outerwear indoors, such as leather jacket and thick cardigan coats. For pants, I tend to just wear leggings or basic slacks, but you can def layer thermal leggings under whatever you’re wearing, or pick up some fleece lined pants! Other accessories that make a difference is good quality wool socks (i like smart wool and bombas), and some heated office goodies like an electric lap warmer and hand warmer!