Ductless HVAC systems can be a viable solution in certain situations. Applications range from residential and commercial to industrial.
They can be the best option for room additions, flat roofs, and a number of other structures. They are energy efficient and can be installed quickly with no duct work which will lower labor costs and time. They are also called a mini split which consists of an indoor unit and an outdoor unit. If your house is without ducts then a high efficiency ductless or mini split should be considered. 
A split system has several advantages over a window unit, a thermostat that can keep each room a constant, comfortable temperature instead of kicking on and off trying to control the temperature in the whole house. In addition, the unit does not have to be moved in and out of the window according to the season.
