I think this is an overstatement of the situation; it's true that you're supposed to keep the house from getting too cold, but it's within living memory in many

I think this is an overstatement of the situation; it's true that you're supposed to keep the house from getting too cold, but it's within living memory in many places that in the colder parts of the winter, standing water jugs would have a thin layer of ice in the morning. They wouldn't stay below freezing, but they'd cycle through temperatures much below 60F (15C) on a daily basis for several months of the year. Even now I think it's more common to set the thermostat down around 50 or 55 when you'll be out of town, and I know people who don't set it much above 60 in the winter even when they're awake and at home, quite a bit lower when they're asleep or out.