My sister has one of those portable A/C's . Her house was gigantic 3bds - 3 baths, off of an open span LR and kitchen and the house was 80ft wide by 60ft deep with 24ft Cathedral ceilings and I was shocked that that small machine kept her house very cool. Her electric bill went down by almost $300. a month by not using her central air unit. I am not a fan of AC but if I was I'd get one.