A split-system central air unit is located outside of the house and is attached to a series of duct work that runs throughout the house. The cooling unit is usually tapped into the same duct work that handles your heating unit. This type of system keeps the noise of the unit outside and the cool air inside.
If your home does not have duct work but has an open floor plan, this would be a feasible option. A large window unit can be installed into an exterior wall. Framing the unit on the inside and outside will make it look like it is part of the building's structure and will not detract from the home's appearance. This alternative can also work with a central air unit. The duct from the unit will run directly into an exterior wall and will be covered with an air vent, allowing the cool air to enter the area.
A portable air unit is an economical option for a single room. This type of unit usually provides heat as well as cool air. This unit is just as noisy as a window unit. Most of these units have a vent hose similar to a dryer vent hose that will need to be vented out through a window or an exterior wall. The unit comes equipped with the parts needed for window venting. If you would like to vent it through the wall you will need to purchase a dryer venting wall plate and an outer flap-style vent cover.
Evaporation coolers are also known as swamp coolers. This type of cooling unit pulls air through damp filters, cooling the air before it enters the house. Swamp coolers can be installed on the roof or exterior wall. Roof-mounted swamp coolers are usually connected to duct work that runs through the attic, but they can also be ductless. Wall-mounted swamp coolers can also be connected to duct work that runs under the floor or can be ductless. This type of unit puts some moisture in the air and for this reason they are not widely used in humid regions. Evaporative coolers use 60 to 80 percent less energy than window air conditioners.