Packaged HVAC equipment is the most common source for HVAC in small and medium commercial buildings, including retail stores, supermarkets, and restaurants. The U.S. Department of Energy estimates that rooftop and unitary air-conditioning equipment accounts for about 1.03 out of a total of 1.66 quads (62%) of total energy consumption for cooling the current building stock of commercial buildings in the United States. Generally, packaged equipment is smaller, more numerous, and not as well maintained as large built-up systems. Because of the large numbers, service technicians cannot afford to spend much time on each unit. In addition, the units are not located in highly visible equipment rooms where it is convenient for onsite technicians to visit daily.