could the issue be that homes are built with lighter materials?
I'm from Europe, and we get really cold winters. My apartment never drops below 17°C even without heating on. Even individual homes, I know are insulated so it never is too cold.
They are also built with the expectation that heating is cheap - just whack in a gas ducted heating unit and run it 24/7 over winter! For a long time it was cheaper to use more energy to heat the house than to pay for the materials to make it more efficient.