Ductless HVAC systems (or mini-split systems) are extremely efficient and provide consistent room temperatures. A ductless heat pump or air conditioner typically consists of a wall-mounted unit running from an outside compressor.
It is most often used in places where a window AC or baseboard heating would be an option. However, unlike window units, ductless units require only a very small hole to be drilled into the wall, making them less visible and audible.