If it's too cold for you, then, basically, it's too cold for your dog UNLESS she has a double coat (natural). Most dogs would be okay as long as they are out of DRAFTS which is what can be a killer. An outdoor would have an insulated Kennel with a bench to get up off the drafts on the floor. But they would live out, not be out there and indoors most of the time, so the outdoor dog would grow a thicker natural coat for Winter.
ps. If your home is regularly in the low 70sF your dog should be fine. I have mine in with me and my bedroom isn't that warm (it's been down to 17C overnight the past few nights when we don't have the central heating on.) My Whippet has blankets and burrows under them. My Basset, with obviously a thicker natural coat, is fine.