AC means you’re keeping heat out in the summer. A well-insulated house is cheaper to heat in the winter and cool in the summer. Traditional housing in warm climates focused on removing heat from homes but fans take take little energy to move lots of air so that's not a major issue in a modern home.

The real gains come from managing solar heat gain. A fairly small solar hot water heater can keep a well insulated house warm in most of the world, other options include things like a solar porch etc. External shade can also drasticaly reduce heat gain in the summer.

Pushing past that and using things like ground source heating can also work, but they rarely pay off.

Perhaps a home of the future might have the ability to roll the sheet up or down like window blinds inside the wall depending on the outside environment to self regulate.