An energy management system for use with a temperature controlled unit for food or beverages. A sensor is provided that comprises means to measure a temperature in the temperature controlled unit, and means to transmit wirelessly the measured temperature to a controller. The controller comprising a memory for storing data, and a processor arranged to control electric power to the temperature controlled unit on the basis of a combination of the measured temperature and the stored data. The stored data defines at least two time periods in which a first temperature is required in the first time period, and a second, different temperature is required during the second time period.