Sims are freezing to death

Moontjuh22  Since sims are freezing to death, I assume you have Seasons.  So, sims will still freeze and die if there is no heat in the house.  To fix that, install a thermostat and adjust the temperature.  You will have to change the setting of the thermostat depending on the season and which world you are playing in.  So, turn it to heat in the winter and to cool in the summer.  You'll know by the buffs on the individual sims when they get cold or hot so you'll know when you need to adjust the thermostat.  You can avoid sims freezing or overheating altogether for children and above by buying the buyable traits too but that doesn't help when you have toddlers or infants since you can't buy the traits for those life stages.  You have to spend reward traits to buy them which in a lot of cases, children and teens won't have earned enough points for the purchase either.  It really depends on how you play.  If you work towards completing a lot of aspirations, you get a lot of reward points.  If you play differently and don't chase aspirations, then you won't be able to buy a lot of the buyable traits.  

Hope this helps.

This helps a bit, but i do have a thermostat in the house and radiators all over. So i put the thermostat on high, because of winter, but they still froze to death. I now have repaired the game in hope that works. Cross your fingers for me!

I now see another strange thing: normally it says when there is something bothering the sim how long it takes to fade away. with the freezing cold for all my 3 babies it doesn't give any time on it. But they are also nice and warm from the heater but because there is no time when the cold goes away they stay freezing cold. How can I get this straight?

I wouldn't bother about that if it were me.  Babies can't die from it.  You are correct though; the freezing and overheating buffs should go away soon after you turn the heat on so they shouldn't be there for more than a few hours.  But buffs do get hung on sims sometimes.  There's not anything that I know that can do to get rid of them if you play without mods.  There are few mods that allow you to get rid of them if you do use mods.  UI Cheats can do it for instance.  I'm not sure you can do that for babies anyway.  I think it only works for infants and above. Otherwise, you have to wait them out.  Since yours are babies, they might go away when you age them up to infant or if the season changes to Spring.  

I assume the adults are the babies' parents.  So, if both continue to die as soon as you load into the lot and there is at least one sim remaining in the household that is teen or above, you could just let them die and then resurrect them or just continue to play them as ghosts once you get them to join the household again.  Once you get a ghost to join a household, they become playable again, so you have plenty of time to resurrect them later and just play them as ghosts in the meantime.  Otherwise, you will need to make Ambrosia or, if you have the Romantic Garden pack, use the wishing well.  If you don't have another teen or above, then you can temporarily move one in to keep the Social Worker from taking the kids away and to ask the ghosts to join the household.  I haven't had that happen in a very long time so I'm not sure what happens in that case, but I seem to remember that if both parents die and no other teen and above sims are in the household, then you might get kicked back to the world screen and the kids simply disappear from the game.  I might be completely wrong on that as the game has changed a lot since I last had it happen.  And it is my understanding that if you have the Life and Death pack and have a will, then the kids might be sent to live with whichever household that the will has designated.  Again, I am not sure on that since I haven't had that situation in my game nor have had a sim make a will yet.

Hope this helps.