In addition to the savings that come with being an efficient heat pump, ductless heat pumps save energy and money by avoiding the use of ducts or using much more compact duct layouts inside the conditioned space. That’s because ducts are often sources of heat loss where not properly insulated and sealed, especially if installed in unconditioned attics or crawlspaces. The indoor unit is mounted on a wall, where it directly warms or cools a large part of the home. More than one indoor unit can be placed in the home in combination with a single outdoor unit. Additionally, some indoor units can be integrated with simple duct layouts. The outdoor units are smaller than standard heat pumps.