Most homes have wall insulation in the cavities not outside the framing.
Ac ducting inside room without attic.
However it absolutely must be an unused chimney in an unused fireplace.
Good luck getting better cooling in the upstairs in an old home using a basement hvac system than one in an attic.
If the walls are framed with 2x4s there s often not enough space even for a little bit of duct insulation.
When you decide to trade in your room air conditioner for central air you ll have decisions to make including where.
Quit writing papers and go try a seat of your pants experiment.
Sure if you can find enough space and afford the large cost to have someone poorly carve up the inside of your house to get the proper sized ductwork through the house.
You can pipe the hot air out through a chimney.
An hvac return air duct should be in every room except a bathroom and kitchen.
Never try to vent a portable ac unit through a functional working chimney or fireplace that s a huge safety risk.
There s one more way that you can vent a portable ac unit and get rid of that hot air in a windowless room.
Can you put your air conditioning unit in the attic with blown in insulation.
Duct losses to outdoors.
They should be on interior walls across the room from the supply ducts that should be washing exterior walls with conditioned air the red arrow points to a large wall mounted return air vent.