It's not that simple. If all of society turns all of it's home heating to max at 5pm to prepare for a 6pm arrival, we'll need to overinvest in either generating

It's not that simple. If all of society turns all of it's home heating to max at 5pm to prepare for a 6pm arrival, we'll need to overinvest in either generating capacity or storage. Not to mention the fact that houses aren't completely empty when the adults aren't there. Kids, pets, plants, and last but not least, pipes with water in them. All of these will die horribly in cold temperatures.