I don't wanna sound like a nerd and I might not be right, but the electricity that is used in the refrigerator is getting used to make the refrigerator colder, besides, you choose what temperature ot should stay as, however, if you set it to - 17 Celsius and it's - 20 celsius the temperature of the refrigerator would be - 20 because it's affected by the environment. Am'nt smart enough to think of more arguments but that was my theory