Yes. I live in a hot area of the US. Walls and ceiling need insulation so you can keep the house cool. Usually by Air conditioner. Attics a lot of time are under insulated so cause a the AC unit to work harder to keep it cool. Attics are not livable or a good place to store stuff. Where I live most houses are built on concrete slabbing so you don't have a crawl space under your house.

Mine is a pretty backwards situation lol.

The crawlspace under my uninsulated floor will get cold enough a few times in the winter that we've had to install heat tapes to keep pipes from freezing. I put a wireless thermometer down there and it'll average temps in the mid-upper 30's January and February. No one walks barefoot in the winter because it makes your feet hurt lol.

As for the heat, being such an old house we have hot water baseboard heat. We finally figured out that we think they have it pumping the wrong direction, because the hottest water off the boiler heats the second floor before coming down to heat the first. This means I set the heat in the winter to 64 (one thermostat in the center of the first floor) and the second floor will be 78 in the bedrooms and the first floor will be 63-64. If we try to heat the first floor beyond that we have to open windows on the second floor to exist up there. And yes, this is with blocking the stairwell to reduce heat that rises through there. I'm also assuming there's not much attic insulation either because snow really doesn't stick to the roof. I'd check the attic, but there's currently no access and we'd have to decide which ceiling to cut a hole in for greatest convenience.

Some day with enough money it'll get fixed, but for now the focus is just keeping the bills paid.