[Lee Stewart]

An empty fridge not only makes it more difficult to decide what to snack on, it also wastes valuable energy. It works like this: the more empty space in the fridge, the more cold air is displaced by warm when you open the door, requiring the appliance to generate cool air to replace it. If the fridge is packed, less cool air escapes and less energy is required to replenish it. The writers at The Kitchn go so far as to advise fridge owners to fill empty bottles with water in order to displace the empty air.