Window air conditioners fit into the lower part of a window and can be moved from window to window and thus the name, Window ACs. Self-contained air conditioners are the large room air conditioners. Central air conditioners also use electricity or gas. They can supply conditioned air to a number of rooms or to an entire building from one central source. Fans blow the conditioned air through air ducts from the air conditioner to the rooms.
Central conditioners have a number of advantages over other kinds.
For example, all the equipment for air conditioning a large area is located in one place. This reduces the cost of cleaning and repairing. Central conditioners can also be zoned i.e. they can supply air of different temperature to different parts of a building. Combination room and central air conditioners are used in large buildings. The demand for non ducted products grew steadily in the latter half of the 1990s.