So each clothes dryer appliance has an exit port. You connect a hose to it to vent the damp air to the outside.
I want all dryers to have an intake port so that I can use cold air from the outside for drying. This will keep me from using (expensive) warm air from the inside of my house.
I suspect this will also make the dryer more efficient because the cold incoming air could contain less humidity.
All points to be considered, but the port could be left unattached to an outside source. Those who don’t want to make use of outside air wouldn’t have to.