Like in the original Frostpunk, keeping your citizens and buildings warm in Frostpunk 2 is the top priority for success. Not only will warm citizens stay happier and refrain from overthrowing you, but they’ll also be more productive and have a higher level of Hope. Keeping my city warm in the original Frostpunk is the most annoying mechanic to keep track of, but as long as you understand how it works, you’ll be okay.
https://screenrant.com/frostpunk-2-reduce-cold-best-methods/