Yes they are. Many people think that it is quite impossible to cool a whole house without having ducts snaking throughout. But it is not so. A unit without ducts can also cool the whole house. The only thing need to be taken care of is appropriate placement. In most cases the indoor unit is placed at the top of the stair landing on the second floor. The air coming out of the unit can cool the send floor well. The air cab also go down (being heavy and dense) to the first floor and cool it. Through the principle of natural convection, the whole home can be cooled quickly. Hundreds of homes are being cooled this way. Usually only one 12,000 or 15,000 Btu/h unit is necessary