I had a sim freeze to death inside a spa (the one that comes pre-built with Spa Day) during cold weather the other night. I was playing with mods & CC turned off since the patch. It was Malcom Landgraab working as a massage therapist. I'd set the spa in Newcrest and it was Mystery Weather Day so it's possible it was only cold and not freezing by the time the camera focused on him freezing.
I noticed my sim was chilled while in the basement. I thought that bug was back but she stayed chilled when I sent her up to the living room. I also noticed that in Sulani, a sim was swimming with blue skin from being chilled. It was hot and it was outdoors without a thermostat anywhere. So, they got chilled somewhere else and stayed that way. The only way I could get the chilled moodlet to go away was to cheat it away.
I haven't played in a few months so I don't know if this is a recent problem or not. It wasn't there last time I played.
November 2019 - last edited December 2019
I don't think this would help if sims are freezing to death indoors, but I was getting the chilled moodlet inside. I finally made a small mod that widened the temperature range of the neutral temp by ten in each direction from -29 to 29 to -39 to 39 (the temp after heat, outside temp, clothing etc has a range from 100 to -100). I also adjusted all the other temps by the same margin (kind of had to or they'd overlap). There are temp ranges from neutral to cool to cold to freezing, etc. I haven't seen the moodlet return. My guess is the mathematics of what temp a sim indoors on a cold day with regular clothes and a thermostat set to warm is a bit off and wasn't always hitting the neutral range.
EDIT: Maybe, maybe not. Didn't seem to totally fix the problem.
This is still happening. Have tried it with thermostats and fireplaces and still nothing. Happens in every household. Had the central heating buff and chilled buff at the same time. What's up with this. Is somebody still working on it?
December 2019 - last edited December 2019
Okay, I was a bit off. Not positive, but the way the game stands, this might not really a bug, at least if people are having the problem when it is super cold outside (freezing). It may intentionally leave a gap so that if it's cold enough outside, your sim may still feel it inside, and have to dress warmer, light a fireplace, take a hot shower, etc. But even if it is messed up, I just modded the effective temperature (how many degrees it adjusts a sim's temperature) of the thermostat, widening its range when set to warm/cold from 15/-15 to 25/-25, and that seems to have solved it.
Edit: And a really nice solution I just discovered is modifying the "Loot_globaltemperature_inside_Cold/hot/freezing/burning" and changing the two values to 0. Kind of think it will mean that no matter what the temp is outside, it will be zero inside, which is dead center of a sim's comfort zone. Hopefully it will mean the end to all thermostats, so no need for them on any lots. Never did add much and only annoying to have to put them on community lots.
I've definitely run into this in my game. With the thermostat on heat, and a fireplace lit. In every room without the fireplace my sim will feel the effect. NPC sims also feel the effects and can be visibly seen shivering. Walls and ceilings have all been replaced, thermostat as well. The only workaround I've found that seems to work is to change into an outfit that is properly tagged for cold weather. That won't get rid of the chilled moodlet, but it will turn your sim back to normal if they're looking blue and about to freeze to death. I haven't personally tested if CC clothing tagged as cold weather works, but that may potentially be another option to keep your sims from turning blue as well.