Refrigeration systems account for about 10 percent of electricity use in the commercial sector. About two-thirds of this is consumed by "packaged" refrigeration systems, which are factory-built units. Commercial refrigerators and freezers, ice makers, water coolers, and beverage vending machines generally incorporate both the refrigeration system and the refrigerated compartment in a single package. Small walk-in coolers and ice makers may be self-contained "packaged" systems, or may use a remote condenser similar to residential central air conditioners. Several of these systems are found in many common building types. Hospitals, schools, and hotels, for example, often have ice makers, and reach-in refrigerators and freezers. In addition, water coolers and vending machines on several floors are common in office buildings, and reach-in refrigerators and freezers, and ice makers are common where food is sold.