a refrigerated appliance such as a refrigerator receives a demand response signal indicating a peak demand period and operates the refrigerator in an energy savings mode by disabling an anti - sweat heater . sensors monitor ambient temperature and humidity , and the dry bulb temperature of a preselected region where incipient moisture would likely form . data from the sensors is sent to a controller which calculates ambient dew point and compares the dry bulb temperature of the preselected region with the calculated dew point to enable the anti - sweat heater during the peak demand period and prevent incipient formation of moisture .