My floor is concrete also. The cold was the 'other' issue as working/standing on it all day took a toll on my back/legs/feet. My DH went to a local farming supply store and bought me "cattle" pads. They are about 4' X 6' pads meant to put in livestock pens - but they work perfectly in not only insulating the cold, but fixed my pain problems as well. Sounds crazy, but... they are about an inch thick and I, like the livestock lol, can stand on them all day without issue!