I thought all heating systems had outdoor input for temperature. I know all houses I have lived in has had that the last 40 years at least. But I live in a cold

I thought all heating systems had outdoor input for temperature. I know all houses I have lived in has had that the last 40 years at least. But I live in a cold area so I guess that's different. -38 C is uncommon but happens now and then. Also the isolation of the houses are better and that also helps with leveling out temperature differences.