The main advantages of mini split air conditioning systems are their small size and flexibility for heating and cooling individual rooms. Many models can have up to 5 indoor air handling units serving 5 different rooms connected to one outdoor unit. Each of the room will have its own thermostat, so you only need to condition that space when it is occupied, saving energy and money. The most common applications are in residential housing, office spaces or as retrofit add-ons to houses with "non-ducted" systems. They can also be a good choice for room additions where extending or installing distribution ductwork (for a central air-conditioning or heating systems) is not feasible.