Why? Which DC voltage? The low voltage that use now is too low voltage for running in the walls. You're going to need converter boxes; DC-DC converters are more

Why? Which DC voltage? The low voltage that use now is too low voltage for running in the walls. You're going to need converter boxes; DC-DC converters are more efficient but you are going to have wall warts everywhere. Also, USB-C is not enough power for things like TVs. Plus, I have a bunch of things like fans and lamps that need AC. So now going to have converter boxes from AC toDC. Also, appliances are where all the efficiency gains are because that is where all the power goes.