You are asking the wrong question. While you could save fuel that way, far more can be saved by insulation and turing temperatures to where you feel comfortable, and the with better insulation you don't have to suffer message is a winner with people who in abstract agree with saving fuel until it hurts them.

The real question then is how can you insulate every place in your country better.

The above is a complex question. There is the supply chain of insulation, contractors to do the work, and how to pay for it all. Still it is worth looking at.