The portable ac unit moves the air and it should be able to enter the space with little resistance. Free movement is not the best as it allows equalization of the inside and outside temperatures too quickly. The goal is to create a difference in temperatures for the spaces, making the installation of an air conditioner for windowless room use a challenge.
Portable ac units function just like the central ones, however, the entire unit is inside the room being cooled. Even window or through the wall units are half inside and half outside the room. The portable cooling unit must have a connection to the outside. This is normally accomplished using a 5 inch duct approximately five feet in length. A window adapter (a flat piece of plastic or foam designed to fit inside a sliding window) allows the ventilation path to be established. It is easy to install and works well.
The question comes when the room does not have an opening window.
Owners do have options. One is through the ceiling. This is easy in rooms that use drop ceiling tiles, as is common in office buildings. An adapter replaces one of the tiles to which the adapter is attached. This is a good option in many computer server rooms, but works anywhere drop ceilings are installed.
In rooms with sheetrock ceilings, a hole can be cut into the ceiling and the adapter attached. However, ceiling ventilation does cause a problem, especially in areas of high humidity. Depositing the moisture pulled from the air in the attic may not be a good idea. If the unit offers a drain tub and there is a plumbing drain available it should be used. In addition, the attic space needs to be large enough to handle the extra heat or offer external ventilation access.
Another alternative is to install a dryer vent as used with a clothes dryer. This establishes an inconspicuous, permanent portal for ventilation that is easily used. It does require cutting a hole in the wall. The setup allows placing a unit anywhere one might desire.
Casement windows create problems as well. There are currently no commercial products available to ventilate the units through this type of window. However, it is possible to cut panes from plexiglass to fit the window frame when the window is open. A hole is then cut through the plexiglass to connect the hose. The new pane screws into the window frame and caulk is used to seal it.
While primarily designed for use in rooms with sliding windows, portable air conditioners can be used in other spaces as well. The installer must provide an alternate method of creating ventilation. This sometimes requires additional cost and work, but should help to improve the room comfort with few issues.
Our favorite windowless air conditioner is the Whynter 14,000 BTU Dual Hose Portable Air Conditioner. This is a terrific unit that will keep you cool all summer long.