I'm currently on the first floor of a triple decker, NO insulation whatsoever, about 1000 square feet, we keep the heat no higher than 60 degrees (we freeze all winter) had to get 3 or 4 fill ups last winter with the last fill up costing $600. That's why we are now moving outta there. Previous winters we only filled twice and could stretch a tank for months, this winter it seemed we filled every 6 weeks like clock work.