In this article, I'm getting away from the kind of air cooler that doesn't need venting at all, namely the "evaporative or swamp cooler." The reason for this is that there are a lot of people who live in areas of very high humidity where they don't have the option of using evaporative cooling and an AC is their only way to stay cool when it gets really hot and humid.
Best Portable Air Conditioners to Use
There are several great room air conditioners available to buy that are perfect for venting via alternative means than a window if the need arises. Here are some of my top picks that can be bought online from Amazon:
Simply click the image of the unit that you want and you'll be transferred to the relevant page at the Amazon website.
Venting a Portable Air Conditioning Unit
So let's look at why you need to vent a portable AC in the first place and not just leave it to stand alone in a room turned on and sounding like it's doing what it should be doing. As I mentioned above, all AC units whether fixed or moveable produce a hot, moist stream of exhaust air as a by-product of the refrigeration process that is happening under the hood that you don't see.
There is no avoiding this, because that's how AC works!
Room temperature air is drawn into the unit where it is passed through the internal refrigeration process that acts in a similar way to a domestic fridge. A heat exchange mechanism works by chilling a refrigerant gas using a compressor and forcing that very cold gas through a series of fine tubes in a lattice, looking something like a radiator.
In fact, that's exactly what it is. The warm room temperature air is forced through the cold radiator and is itself chilled and dried. That chilled, dry air is then pumped out of the unit into the room by a fan.
The other side of that heat-exchange equation is the hot air produced by the compressor (mechanical energy) that gets mixed with the moisture that was stripped from the air passing through the refrigerated radiator. That has to be evacuated from the unit but not into the same room being chilled with the cold air, or it would cancel out the cooling effect!
So you can see it is not possible to have a true portable air conditioner without exhaust capabilities because that hot air must go someplace.
Getting the Unwanted Hot Moist Air Out of the Building
So that hot, moist air has to go outside the building for best efficiency. Normally, a portable AC would simply get hooked up to an available window fixing kit using the flexible plastic exhaust hose provided. But we have no window!
In that situation, there are still options, but they require some additional minor construction work to be done. In short, there needs to be a hole made in an external wall so the AC's vent can connect to it and exhaust the air through it to the outside.
That is often the simplest solution and provides a more aesthetically pleasing setup as the hose can be better concealed low down out of sight with the AC unit placed directly in front of the newly created wall vent.
Another solution is to use a false ceiling space to install an exhaust duct that runs to an external wall to provide an outlet for the unwanted hot air. This is more difficult and usually requires a professional installer to carry out the work.
Either way, you are provided with a means for exhausting the moist, hot air from the AC out of the room and building leaving you with a nice cool environment to relax in!