We store food materials in Refrigerators and Freezers to prevent them from going bad prematurely.
Reducing the total number of hours of operation of the refrigeration units reduces the consumption of electrical energy.
During the winter months, in some parts of the word, the temperature falls below the freezing point. In these parts of the world, we can use this cold temperature to cool the Refrigerators and the Freezers without running the Refrigerator mechanism.
This will result in large savings of energy. Especially in large Grocery stores who use huge Freezer and Refrigeration units.
As shown in the diagram, the cold air from outside the building is blown through the Heat Exchanger. The warmer air from the Freezer or the Refrigerator is also passed through the heat exchanger, which loses its heat to the outside cold air.
Thermostats in the Freezer or the Refrigerator unit regulate the operation of the Blowers to maintain the required Temperature in the Freezer or the Refrigerator.
Thus the Freezer or the Refrigerator is maintained at the desired temperature without running the Refrigerator mechanism.