Save much money - compared to what? Any insulation can save money on heating We had spent a winter in this house before we could insulate it (16cm|6.3" graphite+EPS on the walls, 10cm|4" XPS on the footing, 25cm|10" mineral wool around the attic, and 31cm|12" EPS+mineral wool combo around the new bathroom), and the devices we can use for heating (no, today they're not needed) are toys compared to the old stove, which wasn't even enough on cold winter days. We're almost all electric now, which is a step toward independence. Solar panels and/or wind generators would be another. One day we can hopefully afford them.