And I have seen people use mobile air conditioners without properly leading out the warm air that is created out of the building so they basically have a closed

And I have seen people use mobile air conditioners without properly leading out the warm air that is created out of the building so they basically have a closed loop where the aircon fights itself. And even when properly letting out the warm air, new warm air from the outside is sucked in. Typically these types of air conditioners are just plain useless except for cooling one person who sits in the cool air blow. It's also amazing how so many houses in warm countries are so poorly isolated and have bad window screens to avoid the sun heat up the inside of the building.