Ductless heating and cooling delivers comfort to each room directly, without the network of ducts a traditional central system uses. Instead of one big unit pushing air through ducts in the walls and attic, a ductless setup puts a small air handler in each room and runs only thin refrigerant lines to it. The most common ductless system is a mini-split.
The big advantage is avoiding duct losses. The Department of Energy says ducts can waste more than 30% of the energy a system uses, especially when they run through a hot attic or cold crawlspace. Skipping ducts removes that loss. Because each room has its own unit and thermostat, you also get zoning — heating or cooling only the rooms in use, with one outdoor unit feeding up to about four indoor units.
Installation is far less invasive than adding ducts. Connecting an indoor unit to the outdoor one needs only a roughly three-inch hole through the wall, which is why ductless is popular for older homes without ducts, additions, garages, and converted attics. DOE-listed ductless systems reach SEER2 efficiency from 15.2 up to 35, higher than the 15.2 to 25 range for typical ducted equipment.
For a buyer, ductless shines where running ductwork is hard or expensive, or where you want room-by-room control. The trade-offs are the visible indoor units (usually wall-mounted) and a higher up-front cost per room than extending existing ducts. Proper sizing of each indoor unit still matters — an oversized head short-cycles just like any other system.