Older single door manuel defrost refs were very cheap to run and in fact most would be awarded an Energy Star label if still produced today. It wasn't until the late 1950s-the 1970s that refs really became real power hogs. The real culprits were adding frost free freezers, two or more exterior doors, thin wall construction, and through the door ice & water dispensers. FF refs from the mid 1960s- the 1970s can use four times the power of older single door refs. I have worked on some older SxSs that had as many as 16 electric heaters in them. The good news is that new refs are very efficient and like the early refs they use about 1/4 the power of earlier FF machines and they are keeping food more evenly cold plus with the improved insulation food can remain frozen for days if a power outage occurs. A new FF ref should last 20=30 years with good care and a manual defrost upright or chest freezer could still last 25-50 years.