You got some really good suggestions for keeping warm(er), hopefully something helps you. Last Winter was extremely cold, hopefully this year will not be as extreme. Just be careful turning all sources of heat off when you are not at home, frozen pipes are no fun. I am not sure I would leave most electric space heater on when you are away either. If you can talk the grandparents in to a wood stove it would certainly be worth the investment in the long run.