This 13 SEER - 12,000 BTU Ductless Mini split air conditioner is a great cost efficient system for cooling areas over 500 square feet. Like any A/C you need to know how many BTUs are needed for the area you are trying to cool - heat. A mini split air conditioner is very quiet and efficient, but it is more expensive than a window or portable system. Since they are ductless, the mini split AC/Heaters avoid the energy losses associated with the ductwork of central forced systems