The majority of American air conditioning units are window mounted, like these: https://www.consumerreports.org/window-air-conditioners/how-to-size-a-window-air

The majority of American air conditioning units are window mounted, like these: https://www.consumerreports.org/window-air-conditioners/how-to-size-a-window-air-conditioner/ https://www.consumerreports.org/window-air-conditioners/how-... As an example, the house I grew up in, late 1940s, was piped for heating only, to an oil furnace. When my parents wanted an AC, they got a window unit. (Bonus: The original heating system had ceiling vents, at some points the house was re-vented for floor vents) My place has in floor heating, if I wanted AC there aren't any vents in my house, so same thing, I'd have to get a window unit.