This paper presents the results of “Upgrade and Save”, a program to upgrade the standard electric furnaces and air-conditioning units in Mobile Homes for energy-efficient heat pumps. This program is implemented in North Carolina, USA and pays about $700 through a rebate provided by the North Carolina State Energy Office to the Mobile Homes' owners. The goal of this project is to subsidize low-income families by lowering their heating cost in the winter as well as improving their homes' indoor thermal comfort. More than 300 mobile homes have participated in this program. Field measurements, meter readings of the actual electrical consumption, and annual building energy simulation were used to measure the dollar saving and the indoor thermal comfort improvement in the mobile homes after the heating system upgrade. This research proved that the dollar saving of using the heat pump for heating in mobile homes ranges from $51 to $128 annually.