A similar approach works in hot climates. A friend of mine saved a substantial amount of money by getting an efficient portable AC unit for his bedroom, and shutting off the main air conditioner for the house at night. In a southern summer, the savings add up quick.
Portable AC units are highly inefficient when compared to large fixed units. If you only want to cool a single room the best solution is probably a mini split. They're expensive but very efficient.
Depends where you live--a house with no air conditioning generally won't suffer mold, and neither will one with air conditioning. But spotty air conditioning without something like a dehumidifier will breed mold and warp floors.
A friend of mine has been complaining about his rental's warped kitchen floor and mold (or the fact that mold forms easily). His windows are mostly painted shut. Can you elaborate on this? What kind of a dehumidifier should he look at?
I have a portable air conditioner but it is not as portable as you would think. It is about 2.5 feet tall, sits on nice rolling wheels and has a small exhaust and fitting so you open your window and put the pipe end in place to vent the heat. You do not have to mount it in the window which makes it portable. I can move it from room to room and it only takes about 2 minutes to setup the fitting.
